https://orcid.org/0000-0003-0968-6240
ABSTRACT
Dengvaxia is the first dengue vaccine recommended in the United States (U.S.). It is recommended for children aged 9–16 y with laboratory-confirmed previous dengue infection and living in areas where dengue is endemic. We conducted focus groups with parents and in-depth interviews with key informants (i.e. practicing pediatricians, physicians from immunization clinics, university researchers, and school officials) in Puerto Rico (P.R.) to examine acceptability, barriers, and motivators to vaccinate with Dengvaxia. We also carried out informal meetings and semi-structured interviews to evaluate key messages and educational materials with pediatricians and parents. Barriers to vaccination included lack of information, distrust toward new vaccines, vaccine side effects and risks, and high cost of/lack of insurance coverage for laboratory tests and vaccines. Motivators included clear information about the vaccine, a desire to prevent future dengue infections, the experience of a previous dengue infection or awareness of dengue fatality, vaccine and laboratory tests covered by health insurance, availability of rapid test results and vaccine appointments. School officials and parents agreed parents would pay a deductible of $5–20 for Dengvaxia. For vaccine information dissemination, parents preferred an educational campaign through traditional media and social media, and one-on-one counseling of parents by healthcare providers. Education about this vaccine to healthcare providers will help them answer parents’ questions. Dengvaxia acceptability in P.R. will increase by addressing motivators and barriers to vaccination and by disseminating vaccine information in plain language through spokespersons from health institutions in P.R.
Introduction
Dengue is a vector-borne disease transmitted by Aedes species mosquitoes and caused by any of four distinct but closely related dengue viruses (DENV-1–4). Studies estimate more than 50–100 million symptomatic cases, 10 million hospitalizations, and 40,000 deaths annually worldwide.Citation1,Citation2 In the U.S., 90% of the population at risk for locally acquired dengue live in Puerto Rico (P.R.). Although the case fatality rate in P.R. is low, periodic dengue outbreaks frequently overwhelm hospitals and exhaust health resources.Citation3,Citation4 Most hospitalizations occur in children aged 10–19 y, with approximately 10,000 hospitalizations between 2010–2020.Citation5 Dengue also causes significant illness and loss of productivity.Citation3
Dengvaxia is the first dengue vaccine approved by the U.S. Food and Drug Administration (FDA). It was recommended for routine use by the Advisory Committee on Immunization Practices (ACIP) in 2021. It is a live-attenuated vaccine that protects against all four dengue virus serotypes in children aged 9–16 y with previous dengue virus infection. Overall vaccine efficacy is approximately 80% for protection from virologically confirmed dengue, hospitalization for dengue, and severe diseases caused by dengue virus.Citation6,Citation7 Because Dengvaxia increases the risk of hospitalization or severe dengue in children without previous dengue virus infection who are subsequently infected with a dengue virus, it is only recommended for children 9–16 y of age with laboratory confirmation of a previous dengue virus infection and living in areas of the U.S where dengue is endemic. Age-eligible children can fulfill the laboratory criteria with either positive confirmatory test results (e.g., RT-PCR, NS1 testing) from a past episode of dengue or a positive result for anti-dengue virus IgG antibodies on testing meeting specific performance standards recommended by ACIP.Citation5
Previous studies have assessed perceptions, barriers, and motivators about how parents make vaccination decisions for their children.Citation8–10 Researchers have found that misinformation about new vaccines can lead to vaccine hesitancy and hinder the public health response to epidemics.Citation11–13 Additionally, beliefs about disease risk influence prevention activities such as vaccination.Citation14–16 We explored these domains regarding Dengvaxia by performing a study with the following objectives:
Examine acceptability, barriers, and motivators to vaccinate with Dengvaxia among parents and key informants.
Evaluate the perceived risk of dengue and severe dengue.
Determine preferred educational methods to explain the unique features of Dengvaxia.
Develop Dengvaxia key messages and educational materials based on information needs found in focus group discussions and in-depth interviews.
Evaluate Dengvaxia educational materials in smaller scale vaccine rollout implementation.
Materials and methods
Study design
This study consisted of four phases: Focus group discussions (FGD), in-depth interviews (IDI), informal meetings (IM), and semi-structured interviews (SSI). To examine dengue risk perception, vaccine barriers, motivators, acceptability, and preferred educational methods, we conducted focus group discussions (FGD) with parents and in-depth interviews (IDI) with key informants during January – July 2020.
FGD and IDI
In person FGD were held from January-February with a moderator (behavioral scientist-BS) using a guide of 14–17 open-ended questions to direct the discussion (Appendix A). For phone IDI, conducted from March to July, the interviewer (BS) used a similar question guide tailored to key informants (Appendix A). A script about the vaccine was also read to FGD and IDI participants (Appendix B). IDI were conducted by phone due to stay-at-home orders in response to the COVID-19 pandemic.Citation17
Before beginning each FGD or IDI session, the moderator or interviewer obtained verbal informed consent to participate in this study, record the conversation, and take notes of the discussion. For each FGD, the moderator assigned each participant a number to maintain anonymity. For in person FGD participants completed a self-administered sociodemographic survey, while for phone IDI, the interviewer verbally administered the survey with each participant (Appendix C 1–2). Unique identifiers were used to protect IDI participant’s identity. We conducted FGD and IDI until we reached saturation; that is, when participants’ answers were repeated and the capacity to get new information had been reached.Citation18,Citation19 FGD were held at a Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), a research center and a university facilities’ meeting rooms. At the end of the FGD, parents received twenty-five-dollar travel reimbursement in the form of gift cards for participating. No monetary compensation was given to key informants.
IM and SSI
We developed Dengvaxia key messages based on participants’ comments and information needs after conducting FGD and IDI. Message topics included information about dengue, dengue burden in Puerto Rico, vaccine eligibility, laboratory testing, vaccine safety and efficacy and vaccine breakthrough. To evaluate the messages, on April 2021, we conducted virtual meetings with dengue experts, pediatricians and parents to receive informal feedback. They discussed and suggested alternative wording or new information to be added to the key messages. We took notes of their comments and used them to refine the key messages. Revised key messages were used to create educational materials for healthcare providers and parents.
From January to March 2023, four months after the the vaccine was rolled out, communication staff formally evaluated Dengvaxia educational materials with healthcare providers and parents at health centers were the vaccine was available. Staff explained the purpose of the educational materials evaluation to participants, and obtained their verbal consent. They completed a self-administered sociodemographic survey (Appendix D), and in person semi-structured interviews were carried out using a guide of 5–11 questions that explored the following topics: appropriate language and writing level, content and format, and opinions if materials answer parents’ questions to make an informed decision to vaccinate (Appendix E).
Participants selection
We used convenience and snowball sampling methodsCitation20 for all four study phases. Selection criteria for participants in all study phases were individuals ≥21 y of age. Parents were recruited if they had children aged 9–16 y. For FGD participants, they were from municipalities with historically high dengue incidence, including Ponce, San Juan and Carolina. For the IDI, we also recruited from the municipalities of Bayamón, Guaynabo, Canóvanas and Fajardo.Citation21–23 Key informants were practicing pediatricians, pediatricians offering vaccination services, university dengue researchers, and school officials (school nurses and principals) from public and private schools.
To recruit parents, research team members visited immunization clinics, WIC clinics, and The Boys and Girls Club organization in San Juan, Carolina and Ponce. Staff from the Communities Organized for the Prevention of Arboviruses (COPA) project also recruited parents among Ponce community residents. If parents agreed to participate, an invitation letter was given to them, with the time, date and place the FGD session would be held at. We also made phone calls/text message reminders to participants.
To recruit pediatricians, we had a list of providers who offered their services in the selected municipalities with their contact information; this list was derived from a P.R. Department of Health (PRDH) directory and the American Academy of Pediatrics search engine online. For university dengue researchers, we had a list of researchers from a previous studyCitation24 with their contact information. We recruited principals and nurses from a list of school contacts. We telephone called and invited them to participate. If they agreed, we sent them the invitation letter through e-mail, with the interview date. We also sent reminders through an e-mail or phone call.
For the evaluation of the Dengvaxia key messages we recruited dengue experts, pediatricians and parents who previously participated in the FGD and IDI to offer feedback of the developed messages. We invited them via e-mail or phone calls, and sent them a Zoom meeting invitation 1–7 d before the virtual meeting date. Participants were reminded of meetings via e-mail or phone calls. For the evaluation of educational materials, we recruited pediatricians and nurses working in health centers where the vaccine was available and who counseled parents about the vaccine. Date and time for interviews was coordinated through the centers’ administrative staff. Parents with children 9–16 y of age in the waiting rooms of the health centers were invited to evaluate the materials.
Data analysis
Following the FGD and IDI, two notetakers and a moderator/interviewer verified notes with the audio recording for accuracy. For FGD and IDI, they conducted a deductive content analysisCitation25 of notes and transcriptions, respectively, based on categories developed from study objectives. Participants’ comments were used as the unit of analysis. For FGD and IDI, a moderator/interviewer developed a slide set and tables, respectively, with categories. The analysts reviewed the data and coded responses that exemplified categories. They met to agree upon codes that should be included in the final analysis and populated categories with coded responses. Agreement was reached by consensus.
For the IM, BS, epidemiologists, and communicators, analyzed participants feedback and edited the messages according to their suggestions. Lastly, for the educational materials evaluation a BS and health communication specialist analyzed the content of healthcare providers’ and parents’ answers based on evaluation topics. The BS developed a slide set with key results and participants’ responses to proceed with the edition of materials.
Human subject protection
The study protocol was reviewed and approved by the Institutional Review Board of CDC #7256 and OMB/PRA CDC ID # 0920–20.
Results
Five FGD with 38 participants, that lasted 1–2 h were carried out. Municipality of residence, participants’ and family’s past dengue infection, age and age of children, and education level are summarized in . IDI lasted 30 min-1 h, with a total of 15 key informants, including practicing pediatricians (n = 3), pediatricians who offer vaccination services (n = 3), university researchers who participated in dengue vaccine clinical trials (n = 3), school principals (n = 3), and school nurses (n = 3). Two principals were from public schools, and two school nurses were from private schools. Additionally, two practicing pediatricians and two pediatricians who vaccinate, see patients with the government’s medical insurance. Medical specialty, municipality of residence, participants’ and family past dengue infection, age and education level are summarized in .
Table 1. Characteristics of focus group discussions, in-depth interviews and semi-structured interviews participants*.
Three university researchers had participated in dengue vaccine clinical trials – Takeda and the Walter Reed Army Institute of Research (GlaxoSmithKline) clinical trials. Four pediatricians referred patients to either the GlaxoSmithKline or the Sanofi dengue vaccine trials. None of the parents, school nurses or principals participated in or had their children participate in a dengue vaccine clinical trial.
Six IM with 27 participants, lasting 1–2 h were carried out with dengue experts (n = 11), pediatricians (n = 5) and parents (n = 11). Thirty-one SSI with a duration of 45 min − 1 hour were carried out with pediatricians (n = 8), nurses (n = 11) and parents (n = 12).
The moderator and notetakers analyzed 7 FGD notes and developed 10 categories. The interviewer analyzed 15 IDI transcripts and developed 17 categories. These categories were analyzed and summarized in 6 themes below (). For the final study stage moderators analyzed 6 notes for the dengue vaccine message testing and 31 notes for the evaluation of the educational materials. Five topics were analyzed for the materials (see methods) used in dengue vaccine promotion in P.R.
Figure 1. Flow diagram of data sources, qualitative categories, and themes developed for the assessment of dengue risk perceptions and acceptability of Dengvaxia among residents of P.R.
Theme 1: dengue risk perceptions
Most parents felt they or their children were at risk of getting dengue. They felt their children were at risk because they had gotten sick during outbreaks, had containers with standing water in their surroundings, participated in outdoor activities, had not been infected with dengue previously, and lacked information about how dengue spreads and how to prevent it. School officials mentioned that their schools are at risk of dengue outbreaks because they lacked air conditioning and because their community did not follow recommendations to reduce mosquito breeding sites. Some parents and school officials felt they were at risk because their schools were close to bodies of water or surrounded by mangroves or woods.Footnotea In contrast, two school officials mentioned that their schools were not at risk of getting dengue because they kept it clean and there was no stagnant water in their surroundings.
Key informants mentioned that the community was aware that dengue can be a serious disease, but not as severe as COVID-19, and that if a family member had dengue previously, the parents, family, and community close to them were more likely to acknowledge how serious dengue can be. When asked about their opinion on which age group was most affected by dengue, pediatricians and university researchers agreed that school children, teenagers, and infants were the most affected.
In contrast, most school officials expressed that they believed all age groups were affected. They also said mosquito control programs – based on insecticide spraying or preventive education campaigns – could be strengthened in P.R. However, one participant said he did not see how these activities could control dengue infections and mosquitoes.
- Well, I did not see any change [in the number of mosquitoes] when the street was fumigated; I did not see any change [in public behavior] after a media campaign was on T.V. and there were a lot [public service announcements] … that if I throw away water [mosquitoes will not breed], etc.
Theme 2: dengue as a burden to the economy and to the healthcare system of P.R.
Pediatricians and university researchers believed dengue outbreaks are a burden to the healthcare system of P.R. due to health services costs, including emergency room visits, payments for hospitalizations, laboratory tests, treatment and follow up appointments for medical care. They also thought that outbreaks could be a financial burden if a patient does not have health insurance or must pay for health insurance deductibles. Also, most said dengue is a burden to the economy of P.R. because of work or school absenteeism as parents need to take off from work.
- Yes, it takes a lot of office visits, it takes a lot of admissions at times, lab samples, these are patients that you have to follow every day – whether you decide to admit them or not. In other words, [it’s a burden] from the economic point of view towards the insurance plan or the patient, if they do not have a medical plan.
- … yes, any epidemic is going to be a burden because it is an impact in the place where they work … [it] impacts, the economy in that aspect. [It] impacts at all levels. It is a chain reaction that involves the economic, emotional and physical aspects.
A few IDI participants, said that dengue was not a burden to the island’s economy or healthcare system because the number of people who get sick of dengue is low.
Theme 3: knowledge about Dengvaxia and information needed by participants
Most key informants had heard of Dengvaxia, but few parents had heard of the vaccine. Three parents, one school nurse, all pediatricians and all researchers had heard information about Dengvaxia clinical trials, the required vaccination dose, and complications after vaccination. One parent commented:
-I’ve heard that people who got the vaccine should have had dengue before and I’ve heard that there have been deaths from complicationsFootnoteb.
Key informants had also heard about the history of the vaccine, and its implementation or use in other countries. Parents who were undecided about vaccination said they would feel comfortable vaccinating their child if they received more information on vaccine clinical aspects and the approval and recommendation process, confirmation of insurance coverage, and information on out-of-pocket costs for vaccine and laboratory tests. Parents and key informants wanted to know about the vaccine’s interaction with preexisting medical conditions and other vaccines, like the human papillomavirus (HPV) vaccine, because the eligible age group overlaps with Dengvaxia. They also requested information about the time to wait after a first dengue infection to get vaccinated, the site (e.g., arm, leg, buttocks) and route (i.e., subcutaneous vs. intramuscular injection) of administration, and if it would be mandatory for school entry ().
Table 2. Information requested by focus group and in-depth interview participants about Dengvaxia for decision-making regarding vaccination of children — Puerto Rico, 2020.
Unlike key informants, parents asked for more information about clinical trials in other countries and which countries were using the vaccine. They also wanted to understand the rationale for its use with children aged 9–16 y and its recommendation for use only in U.S. territories and freely associated states. They asked what the approval process entails and how long it takes to approve a vaccine. Key informants’ questions were regarding the dengue tests required to confirm a previous dengue infection, the local laboratories where pre-vaccination testing was available, the timeframe for receiving the results, vaccine storage, and vaccine availability ().
Theme 4: acceptability to vaccinate with Dengvaxia
Parents expressed various opinions about potentially vaccinating their children with the dengue vaccine. Some said they would vaccinate if they received a positive lab result for dengue. However, some parents were unsure about vaccination. They said they needed more information about previous vaccine studies. Participants also said they would need to discuss vaccination with the child’s other parent. Others said they would not vaccinate their children because they were not convinced by the data provided (Appendix B).
Yes
… the blood test [confirming previous infection] gives me peace of mind, and yes, I would consider it.
No
No, because there is not enough research and data … There needs to be something longitudinal where we can see the effects.
I don’t think that it’s 100% effective and safe. … they have experimented with us, like it happened in the past with the contraceptives …
Unsure
I will continue to inform myself a little more, for a little while.
Perceived barriers to vaccination that parents mentioned were lack of or inconsistent information, high out-of-pocket costs, or lack of insurance coverage for the testing and vaccination, time invested in laboratory testing and obtaining the results, vaccine side effects, and the fact that laboratory test results are not 100% accurate. Other impediments to vaccination were that it was licensed for use only in U.S. territories, child illness at the time of vaccination and lower vaccine effectiveness compared to other vaccines (). Key informants also included barriers such as the influence of vaccine hesitant persons, religious beliefs against medical procedures, failure to comply with the multiple doses required for Dengvaxia, possible risks associated with vaccination, aversion to needles, and the need for more than one injection to complete the series. A school principal thought that having fewer vaccination clinics funded by the government would be a barrier because it would lead to fewer children receiving vaccinations.
Table 3. Barriers and motivators identified in focus groups and in-depth discussions for parents to vaccinate with Dengvaxia — Puerto Rico, 2020.
Motivators for vaccinating children included educational forums with parents about correct information on the vaccine, communicating that the vaccine prevents future dengue infections from all four dengue serotypes, previous vaccination results in other countries, dengue epidemiologic statistics in P.R., availability of accurate laboratory tests for confirmation of previous dengue infection, and government and institutional public support for the use of Dengvaxia (i.e., PRDH, University of P.R. - UPR, and CDC). Some parents would vaccinate their children if a dengue outbreak took place in P.R., and a few indicated that age-appropriate or monetary incentives, would motivate parents to vaccinate their children (). Key informants frequently mentioned motivators such as experiencing a death of a family member caused by dengue (e.g., awareness of dengue severity), if the vaccine was required for school attendance, health insurance coverage for laboratory testing and the vaccine, high vaccine efficacy, and short intervals between testing and vaccination. Fewer key informants mentioned motivators such as being at high risk of dengue, that the vaccine dosage is given only within a year in the patient’s lifetime and reminders for second and third doses, respectively ().
Most school staff were uncertain about parents’ willingness to vaccinate because parents either vaccinate when the vaccine is well known or required for school attendance, or if their children have been at a high risk of illness. Only one principal and one school nurse said that they thought parents would be willing to vaccinate.
- From my experience of talking with parents … unless it is mandatory or they have been at risk [of illness], parents would think about it a lot before administering that vaccine.
- Yes [they would vaccinate], because of the importance of eradicating dengue, to be safe …
Parents and key informants were also asked about an acceptable out-of-pocket cost for Dengvaxia. Parents and school officials preferred that the vaccine be free or covered by health insurance. However, most parents would pay a $5–20 vaccine deductible. A few participants mentioned they would pay any price for the vaccine, and an acceptable range would be between $50–80.
Theme 5: pediatricians’ and university researchers’ willingness to recommend vaccination with Dengvaxia
Pediatricians and university researchers were asked if they would participate in a vaccination program with Dengvaxia. All mentioned they would participate. Even pediatricians who do not offer vaccinations in their officeFootnotec would refer patients to immunization clinics as part of the program. Motivators to recommend Dengvaxia vaccination included their support of vaccines in general, their understanding that dengue is a public health priority, and the results of Dengvaxia studies showing efficacy against virologically confirmed dengue, hospitalizations, and severe dengue. For two university researchers, facilitators to participation in a Dengvaxia vaccine program were a defined role for the researcher in the program and well organized vaccine implementation within the university hospital system. One participant mentioned that a barrier was that healthcare providers would need to be paid or reimbursed to provide the vaccine. At the time of the study, for one researcher, not having a 100% specific and sensitive laboratory result would not be a barrier because he believed that it could be addressed by repeating the test.
- There are several strategies such as repeating the test, to reduce risks. I would be willing to be part of it because preventing dengue should be priority number 1.
Theme 6: preferred dissemination strategies for Dengvaxia
Pediatricians and nurses reported that their preferred strategies to disseminate information about Dengvaxia would be to provide training for clinical staff first, including, presentations at medical symposiums, webinars and educational material for doctors’ offices, immunization and academic clinics. For parents, the preferred best messaging strategies were one-on-one counseling offered by a primary healthcare provider, and by staff members in health centers, immunization and WIC clinics; brochures, traditional and social media such as T.V. (news), radio, newspapers, the Internet, Facebook, YouTube; flyers that students bring could home, presenting the information at parents’ school meetings about health, community meetings, videos, and billboards. Participants emphasized that visuals with minimal text are very effective for information dissemination, as well as hyperlinks to references about the vaccine studies for those who wanted more detailed information.
Parents identified spouses, grandparents, pediatricians, and the P.R. Department of Health as influential figures in their decision to vaccinate. Finally, parents identified doctors, nurses, universities, and CDC as the most trusted sources of information.
- If my pediatrician recommends it. [I will use it]
- [It would motivate parents to vaccinate] that the Department of Health supports it. … It is not feasible if the Health Department does not support it.
Final stage: key messages testing and health communications materials
Findings from CDC communications staff testing for key messages and educational materials with parents indicated that a message describing that children can be infected with dengue multiple times is critical in justifying the importance of vaccination to prevent subsequent disease. Pediatricians agreed with the importance of this point, suggesting that key messages should first state a second infection with a dengue virus is the highest risk for severe disease. They could then use this fact as the segue to counsel patients about the vaccine’s benefits in protecting from severe dengue and hospitalizations. They suggested the following prompt:
- Did you know a second dengue infection could be the most severe?
Pediatricians also emphasized that clear messaging was critically important surrounding the need for testing and that a negative test result is a contraindication to vaccination. This counseling could happen with parents after routine screening identified eligible (or ineligible) children. We found that the final key messages addressed all key partners’ questions identified in this study. We adapted these messages for use on the public-facing CDC website (available at: https://www.cdc.gov/dengue/vaccine/index.html).Citation26 Graphics and audiovisual educational materials were also created based on the results and are publicly available on the CDC website (e.g.,: https://www.cdc.gov/dengue/vaccine/parents/resources.html).Citation27 shows a low literacy factsheet for parents to know about dengue and the available vaccine for protection. illustrates a dengue vaccine poster for parents to read at healthcare providers’ offices. shows a factsheet for healthcare providers on how to talk to parents about the dengue vaccine.
Figure 2. Fact sheet - about dengue.
Figure 3. Office poster for healthcare providers – now available: A dengue vaccine.
Figure 4. Fact sheet - talking to parents about the Dengvaxia vaccine.
After vaccine implementation, CDC staff carried out an evaluation of the educational materials with parents and providers in healthcare centers. Parents and healthcare providers found the language appropriate and understandable. Additionally, the content and images improved their understanding of dengue and vaccine information. At parents’ request, information about since when the vaccine has been available was included in a dengue vaccine factsheet. Healthcare providers stated that all the materials helped them answer parents’ questions about the vaccine, and requested additional information including a laboratory testing algorithm figure, which will be incorporated in a screening tests’ webpage. Also, nurses requested one vaccine factsheet that was only available in English to be translated to Spanish. Most parents indicated that the factsheet About Dengue () and the poster Now Available: A Dengue Vaccine () were helpful to make an informed decision to vaccinate. Healthcare providers also requested digital materials like a video to show patients in waiting rooms, and a larger communications campaign about the vaccine utilizing traditional and social media, and community outreach.
Discussion
Our qualitative study is the first to explore dengue knowledge and risk perceptions, vaccine acceptability, barriers and motivators to vaccination among parents, pediatricians, researchers, and school officials for Dengvaxia in a U.S. territory implementing this intervention. Our findings informed messaging and educational materials that are currently in use in Puerto Rico. Furthermore, our results will inform future efforts by physicians, public health officials, health and community organizations engaged in increasing Dengvaxia coverage among eligible populations.
Notably, our study found that parents held a wide range of attitudes toward this new vaccine, ranging from support to hesitancy or delay to refusal,Citation14 contrasting with pediatricians and university researchers, who were willing to recommend Dengvaxia to patients. These results are likely related to lower knowledge of Dengvaxia among parents compared to key informants (i.e., health professionals). Similar results were found in HPV vaccine studies where vaccine uptake was influenced by parents’ sufficient vaccine knowledge where as low knowledge predicted a lower likelihood for vaccine series initiation.Citation28–30 Recent studies in Puerto Rico found that concerns with side effects was a primary reason for dengue vaccine hesitancy.Citation31 Increased messaging to parents about the dengue vaccine, and its efficacy and safety could increase vaccine uptake. In addition to vaccine knowledge, perceiving dengue as a high risk disease is also an important motivator, as found in previous studies.Citation32–34 Underlining the possible severity of dengue is an important consideration when creating vaccine messaging.
We also identified lack of trust in new vaccines as a major barrier,Citation35–37 highlighting the importance of building trust at every level of parents’ network of influence. Unethical medical interventions in P.R.Citation38 were mentioned in our FGD and contribute to this lack of trust. We identified clinicians as a key influencer in this decision, as found previously.Citation13,Citation14,Citation39 Healthcare provider education about this vaccine and training on appropriate counseling, including empathetic conversation, is key to increasing trust.Citation40 Justification of vaccine use for children living in U.S. territories, specifying dengue endemicity, information about clinical trials carried out in P.R., and vaccine use in other countries would help pediatricians answer parents’ concerns about vaccine safety. School officials, another key level within parents’ sphere of influence, stressed that increasing knowledge and awareness about Dengvaxia among school staff could help them to influence parents and family members decision-making practices.Citation14 Lastly, the support and involvement from local science and health institutions in P.R. like universities, PRDH, and CDC, in the dissemination of Dengvaxia information would be a significant step forward for parental trust and acceptability of the vaccine. For example, results from the dengue vaccine intention studyCitation31 showed vaccine acceptability was high among parents who participate in a university project in collaboration with CDC that has been ongoing for years and where dengue prevention is the main topic. Lastly, communications strategies tailoring messages to concerns and information needs with respected and trusted healthcare providers in P.R. could be an important tool as with other vaccines.Citation41–45
Other barriers for vaccination were vaccine and laboratory testing costs and the multiple steps required to complete the vaccine series. A motivator we identified to remove the financial barrier was zero out-of-pocket costs for the vaccine and the testing or a deductible of less than $20. Previous studies of Puerto Rican communities and HPV vaccination found that high out-of-pocket vaccine costs ($100 per dose) were a barrier to vaccination.Citation15 Additionally, rapid, point-of-care laboratory testing appointments followed by vaccination administered shortly thereafter would solve the significant time investment required to start the series, as has been previously recommended.Citation46–48 Pediatricians recommended increasing efficiency in the testing process by including dengue screening as part of routine testing for all age-eligible children. Furthermore, they recommended focusing in-person counseling during office visits on the practical next steps based on test results. For example, vaccine counseling would only occur for those with positive results for a past dengue infection, while those with negative results would simply be referred for retesting in the future, in accordance with local guidance.Citation49 Lastly, reminders for second and third doses and incentives were identified as possible solutions to increasing completion of the three dose series, consistent with previous research demonstrating their utility for improving vaccine uptake and series completion.Citation9,Citation14,Citation50
Study limitations and recommendations for future studies
Our study has several limitations. We included more parents living in urban areas; however, dengue also affects rural residents, and they could perceive additional barriers to vaccination not identified in this study. We were unable to analyze vaccine acceptance based on study participants’ race, education level, or income level. Due to COVID-19 stay-at-home orders, in-depth interviews and informal meetings were conducted virtually, potentially leading to technical challenges that might have restricted the extent of data collected.
Further behavioral science evaluations from rural areas or other areas of the U.S. where dengue is endemic could contribute additional information toward dengue vaccine knowledge and attitudes. After Dengvaxia implementation is underway, program evaluation can help identify ways to increase program effectiveness and efficiency and further increase vaccine uptake.
Impact on public policy in P.R.
We have instituted several public health actions from this data, including creating a communications plan and developing key messages specific to P.R. to communicate vaccine information. In addition, we have disseminated the information to healthcare providers and the public based on participants’ preferred educational methods. We have integrated key partners into the discussion through a local advisory committee on dengue vaccination which included officials in public health, physicians, laboratories, and other partner organizations. Our findings have assisted public health officials in a phased immunization program implementation of Dengvaxia in P.R. Outside of P.R., this study could help other jurisdictions interested in Dengvaxia implement similar research processes.
Disclaimer
The views expressed in this article are ours and do not necessarily represent the official position of the U.S. Centers for Disease Control and Prevention or the U.S. Public Health Service.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
Notes
[a] These are not known risk factors for dengue.
[b] This information is what the public may have heard from the Internet (see referenceCitation41), yet trials (see referencesCitation51,Citation52) showed increased risk for severe dengue and hospitalization among children who had not had dengue in the past.
[c] In P.R., vaccines are only administered at ~400 vaccine provider locations across the island. Most pediatricians do not offer vaccines in their office and refer their patients to these vaccine providers.
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Appendix A.
Sample Questions for Focus Groups and Interviews
I. Focus Groups with Parents
1. What do you know about dengue, and its prevention?
2. Have you or any one in your family had dengue?
3. Do you feel that you or any one in your family is at risk of having dengue? If yes, why? If not, why not?
4. In your opinion, which age group is most affected by dengue?
5. Which actions have you taken to prevent getting sick with dengue? If you haven’t done anything, why not?
6. What is your opinion about vaccines?
What do you think are the risks?
What do you think are the benefits?
7. What is your opinion about having a dengue vaccine available for use with children 9 to 16 y of age?
Do you think there is a vaccine that already protects you from dengue?
8. Were you aware that a dengue vaccine has been approved by the U.S. Food and Drug Administration in May of 2019 for 9–16-year olds living in areas where dengue is common?
If yes, what have you heard?
Read the following script about the DENGVAXIA vaccine (Appendix B):
9. After hearing about DENGVAXIA, what questions do you have about the vaccine?
10. Assuming that the cost of the vaccine and the test are acceptable, would you be willing for your child to be tested and get the DENGVAXIA vaccine if the test is positive for a previous dengue infection?
If yes, why?
If not, what are the reasons?
11. How much would you be willing to pay to vaccinate your children with DENGVAXIA?
Who should cover the cost of the vaccine?
12. What additional information would you need to make you comfortable with your child getting the DENGVAXIA vaccine?
13. What would be the best way to bring DENGVAXIA information to you?
For example: Video, flyers, community/public meetings, Internet, TV, radio?
Which will be the most trusted sources to obtain information about DENGVAXIA?
i. For example: doctors, teachers, nurses, department of health, UPR, CDC?
14. What would prevent parents from letting their children participate in a program where their children are tested first to confirm if they had dengue and then get vaccinated them with DENGVAXIA?
15. What would influence parents to let their children participate in a program where their children are tested to confirm if they had dengue before and then get vaccinated with DENGVAXIA?
16. Who would influence on the decision to vaccinate your children with DENGVAXIA? For example, family members, coworkers, friends, pastor/priest, etc.
17. What information should we include in an informed consent about having Puerto Rican children participate in a DENGVAXIA immunization program in which children will have a blood test before vaccination? (For example, vaccine safety and effectiveness, confidentiality, benefits and risks)?
II. Interviews with Key Informants
A. University Researchers, Practicing Pediatricians and Physicians from Public Immunization Clinics
1. Have you participated in a clinical trial for a dengue vaccine? What was your role? What did the study consist of?
2. In your experience, what do people think about dengue? Do people think dengue can be a serious illness?
3. Do you think there are effective mosquito control programs in Puerto Rico?
If so, why? What program are you referring to?
If not, why not?
4. Do you think dengue outbreaks are a significant burden on the health care system in Puerto Rico?
To the economy of Puerto Rico?
How do you think they are a burden?
5. In your experience, which age group is the most affected by dengue?
6. What is your opinion about having a dengue vaccine available for use with children 9 to 16 y of age?
7. Were you aware that a dengue vaccine has been approved by the U.S. Food and Drug Administration in May of 2019 for 9–16-year-olds living in dengue endemic areas?
If yes, what have you heard?
Read the following script about the DENGVAXIA vaccine (Appendix B):
8. After hearing about DENGVAXIA, what questions do you have about the vaccine?
9. Assuming that the costs of the vaccine and the test are acceptable, would you be willing to participate in a program to test children for dengue and get the DENGVAXIA vaccine if the test is positive for a previous dengue infection?
If not, what are the reasons?
If yes, why would you be willing to participate? How?
Would participating in this vaccination program affect your day-to-day clinic flow? How? For example, what effect it would have in:
clinic flow
staffing pattern
cost
other _______________
10. What additional information would you need to have to participate in a program to vaccinate children with the DENGVAXIA vaccine?
11. What would be the best way to bring DENGVAXIA information to parents? (Probe: Video, educational pamphlets, community/public meetings, Internet?)
12. What would prevent parents from letting their children participate in a program where their children are tested to confirm if they had dengue before and then are vaccinated with DENGVAXIA?
13. What would influence parents to let their children participate in a program where their children are tested to confirm if they had dengue before and then get vaccinated with DENGVAXIA?
14. What information should we include in an informed consent about having Puerto Rican children participate in a DENGVAXIA immunization program in which children will have a blood test before vaccination? (For example, vaccine safety and effectiveness, confidentiality, benefits, and risks)?
B. School Nurses and Principals
1. What do you know about dengue and its prevention?
2. Can you get dengue more than once? Has this school, ever experienced dengue cases?
3. Do you think that this community is at risk of having a dengue outbreak? If yes, why? If not, why not?
4. Do you think dengue can be a serious illness? Do other people think dengue can be a serious illness? For example, in your school; in your community?
5. Do you think dengue outbreaks can be controlled in Puerto Rico by the mosquito control program? If so, why? If not, why?
6. Which actions to prevent dengue have your school/community carried out? If you have not carried out any prevention methods, why not?
7. In your opinion, which age group is most affected by dengue in your community?
8. What is your opinion about having a dengue vaccine available for use with children 9 to 16 y of age?
9. Were you aware that a dengue vaccine has been approved by the U.S. Food and Drug Administration in May of 2019 for 9–16-year-olds living in areas where dengue is common?
If yes, what have you heard?
Read the following script about the DENGVAXIA vaccine (Appendix B):
10. After hearing about DENGVAXIA, what questions do you have about the vaccine?
11. Assuming that the cost of the vaccine and the test are acceptable, do you think parents would be willing for their child to be tested and get the DENGVAXIA vaccine if the test is positive for a previous dengue infection?
If not, what are the reasons?
12. How much would parents be willing to pay to vaccinate their children with DENGVAXIA?
13. What additional information would parents need to feel comfortable about having their child vaccinated with DENGVAXIA?
14. What would be the best way to bring DENGVAXIA information to parents? (Probe: Video, educational pamphlets, community/public meetings, Internet?)
15. What would prevent parents from letting their children participate in a program where their children are tested first to confirm if they had dengue and then get vaccinated them with DENGVAXIA?
16. What would influence parents to let their children participate in a program where their children are tested to confirm if they had dengue before and then get vaccinated with DENGVAXIA?
17. What information should be included in an informed consent about having Puerto Rican children participate in a DENGVAXIA immunization program in which children will have a blood test before vaccination? (For example, vaccine safety and effectiveness, confidentiality, benefits, and risks)?
Appendix B.
Script Read to Focus Group and Interview Participants
Proper Name: Dengue Tetravalent Vaccine, Live
Tradename: DENGVAXIA
Manufacturer: Sanofi Pasteur Inc.
Approved on: May 2019
The U.S. Food and Drug Administration approved a vaccine for dengue in May 2019. The vaccine called DENGVAXIA is indicated for the prevention of dengue disease caused by dengue virus serotypes 1, 2, 3 and 4. The vaccine is approved for children 9–16 y of age living in areas of the United States with frequent dengue cases (the US territories of American Samoa, Guam, Puerto Rico, and the US Virgin Islands). To be eligible to receive the DENGVAXIA, children must have a laboratory-confirmed previous dengue infection. The reason for this requirement is that the vaccine provides about 75% protection against another dengue infection in children that have had dengue in the past. In children not previously infected by dengue virus, an increased risk of severe dengue disease can occur following vaccination with DENGVAXIA and subsequent infection with any dengue virus serotype.
Thus, it is important to have the laboratory test to show that the child has had at least one previous dengue infection. Children who have had a previous infection and are vaccinated have a much lower chance of getting another dengue infection, and if a dengue infection still occurs, vaccinated children are less likely to develop a severe dengue disease. It is important to understand that laboratory tests are not 100% accurate. Another important point to understand about dengue is that most severe cases of dengue can be treated successfully, and death can be prevented if the patient is seen early with good medical care. In Puerto Rico the percentage of hospitalized dengue cases that die is less than 1 out of 100 persons.
DENGVAXIA is administer by injection of three doses (0.5ml each) six months apart (at month 0, 6, and 12) and should not be administer to persons with a weakened immune system, that do not have the ability to respond well to an infection.
Information on the vaccine’s availability in the US territories is pending.
I will be happy to go over this again if you have questions.
Appendix C.
Sociodemographic Data Sheet for Participants of Focus Group Discussions and In-Depth Interviews
C1. Sociodemographic Data Sheet for Participants of Focus Group Discussions
Instructions: Please mark with an X and answer the following questions.
1. Gender: ○ Male ○ Female
2. How old are you? _____
3. How old are the children in your home?
○ None
○ 0-8 years of age
○ 9–16 years of age
5. What is your municipality of residence? ____________________
6. What is the highest level of education you have completed?
○ Grade school
○ Less than high school graduate/some high school
○ High school graduate or completed GED
○ Some college or technical school
○ Received four-year college degree
○ Some post graduate studies (e.g., Master’s degree)
○ Received advanced degree (e.g., Doctorate, Post-Doctorate)
○ Other:________________________________________________
7. Have you had dengue? ○ Yes ○ No
8. Has anyone in your family had dengue? ○ Yes ○ No
a. Who? ___________________
C2. Sociodemographic Data Sheet for Participants of In-Depth Interviews
Instructions: Interviewer: Please mark with an X and answer to the following questions.
1. Gender:○ Male ○ Female
2. How old are you? _____
3. How old are the children in your home?
○ None
○ 0-8 years of age
○ 9–16 years of age
5. What is your municipality of residence? ____________________
6. What is the highest level of education you have completed?
○ Grade school
○ Less than high school graduate/some high school
○ High school graduate or completed GED
○ Some college or technical school
○ Received four-year college degree
○ Some post graduate studies (e.g., Master’s degree)
○ Received advanced degree (e.g., Doctorate, Post-Doctorate)
○ Other:________________________________________________
Note: Question #7 is for pediatricians and physicians only.
7. What is your medical specialty: __________________________________
8. Have you had dengue? ○ Yes ○ No
9. Has anyone in your family had dengue? ○ Yes ○ No
a. Who? ___________________
Appendix D.
Sociodemographic Data Sheet for Participants Evaluating Educational Materials
Instructions: Please mark with an X and answer the following questions.
1. Gender:
○ Male
○ Female
○ Transgender: _____ male to female
_____ female to male
○ Other:________________________
2. How old are you? _______
3. What is your marital status?
○ Married
○ Unmarried living with a partner
○ Divorced
○ Widowed
○ Separated, or
○ Single, never been married
4. Number of children (under 18 years of age) living in the household:
○ None
○ 1-2 children
○ 3-4 children
○ 5 or more children
5. How old are the children in your home?
○ None
○ 0-8 years of age
○ 9–16 years of age
6. What ethnic group do you identify with? (Check all that apply.)
○ Puerto Rican
○ Dominican
○ Cuban
○ Mexican
○ Haitian
○ Other: ___________________
7. What race or races do you identify with? (Check all that apply.)
○ American Indian or Alaska native
○ Asian
○ Black or African American
○ Native Hawaiian or Other Pacific Islander
○ White
○ Prefer not to answer
8. What is your municipality of residence? ____________________
9. What is the highest level of education you have completed?
○ Grade school
○ Less than high school graduate/some high school
○ High school graduate or completed GED
○ Some college or technical school
○ Received four-year college degree
○ Some post graduate studies (e.g., Master’s degree)
○ Received advanced degree (e.g., Doctorate, Post-Doctorate)
○ Other: ________________________________________________
10. Current job: ___________________________________
Appendix E.
Questions for Healthcare Providers and Parents to Evaluate Dengvaxia Educational Materials
i. Questions for Healthcare Providers to Evaluate Dengvaxia Educational Materials
(Show educational material to participants and provide time for reading. Ask the set of questions after each material has been read.)
Materials to evaluate
Fact Sheets
a. You Call the Shots
b. Checklist (Print Format)
Webpage
a. Laboratory Testing Requirements
i. Laboratory Testing Requirements for Vaccination with Dengvaxia Dengue Vaccine | Dengue | CDC
1. In your own words, what do you understand by reading this content?
a. What do you remember?
2. Are the messages easy to understand as written?
a. Is there anything difficult to understand?
3. Please, describe what you understand from the images included?
a. Do the images help you understand the messages?
b. Are the images engaging?
4. After reading this material, do you feel confident in your understanding of Dengvaxia characteristics and its eligibility criteria? If not, why?
a. (If not) How would you change this?
4. (ONLY FOR NURSES) After reading this material, do you feel confident in your understanding of preparing and administering the vaccine to eligible children? If not, why?
a. (If not) How would you change this?
Material to evaluate
a. Video for healthcare providers: Checklist – Determining Eligibility for Dengvaxia
a. Does the video time pace allow you to comprehend the information? If not, what change would you recommend?
a. What do you think about the music?
b. Do you find this format helpful? Why or why not?
(Final questions)
6. Have you talked to parents about Dengvaxia eligibility criteria?
a. If yes, since when? How many parents do you estimate you have oriented?
7. Before this interview, what CDC materials have you read (i.e., website information) or listened to (i.e., webinars) about dengue and about the dengue vaccine Dengvaxia?
a. Have the materials helped you answer parents’ questions about Dengvaxia?
b. Would you need additional materials to help answer parents’ questions about Dengvaxia? Can you give me examples of additional materials that you need?
II. Questions for Parents to Evaluate Dengvaxia Educational Materials
(Show educational material to participants and provide time for reading. Ask the set of questions after each material has been read.)
Materials to evaluate
Fact Sheets/Low Literacy Fact Sheets (LL)
a. What You Need to Know About the Dengue Vaccine
b. About Dengue (LL)
c. About Dengvaxia: A Dengue vaccine fact sheet (LL)
d. Get Your Child Tested for Dengue Before Vaccination (LL)
Poster
a. Now Available: A Dengue Vaccine
1. In the past months, have you seen, heard, or read information about the Dengvaxia dengue vaccine?
2. In your own words, what do you understand by reading this content?
a. What do you remember?
2. Are the messages easy to understand as written?
a. Is there anything that’s difficult to understand?
3. Please, describe what you understand from the images included?
a. Do the images help you understand the messages?
b. Are the images engaging?
4. After reading this material, would you be able to decide on whether to vaccinate your child if he/she was positive for a past dengue infection? Why?
a. What additional information would you need to make this decision?