Risks of low vaccination coverage and strategies to prevent the resurgence of vaccine-preventable diseases in infants in the COVID-19 pandemic scenario: recommendations for Latin America and the Caribbean by the group of experts on infant immunization for Latin America

ABSTRACT

Introduction

The WHO 2030 Immunization Agenda (IA-2030) harmonizes immunization activity plans at community, national, regional and global levels. Additionally, medical societies play an important role. The Latin American Group of Experts on Infant Immunization, established in 2018, advises on the harmonization, update, and optimization of infant vaccination programs in Latin America and the Caribbean (LAC). In September 2021, 41 such experts from 13 LAC countries met to develop recommendations for increasing regional vaccination coverage to avoid the reemergence of vaccine-preventable diseases and/or the occurrence of outbreaks.

Areas covered

The following items were evaluated: (i) immunization challenges before and during the COVID-19 pandemic; (ii) the status of current immunization programs, particularly infant pertussis and polio vaccination; (iii) possible solutions for overcoming vaccination challenges and achieving regional vaccination coverage targets.

Expert opinion/commentary

Medical societies provide valuable recommendations to guide and update vaccination schedules. In the LAC region, possible strategies to achieve target vaccination rates include the use of combination vaccines, strengthening surveillance systems, improving school attendance, advancing vaccine education and confidence, striving for vaccination equity, widening operational capacity, creating strategic alliances, and strengthening the role of medical groups. It is hoped that these recommendations will be implemented in the LAC region.

KEYWORDS:

• Vaccination challenges
• COVID-19
• medical societies
• pertussis
• polio
• recommendation
• regional

1. Introduction

In the Global Vaccine Action Plan (2011-2020) [1], the Pan American Health Organization (PAHO) and World Health Organization (WHO) stated that achieving the immunization coverage objectives for 10 vaccines (hepatitis B, Haemophilus influenzae type b, human papillomavirus, Japanese encephalitis, measles, polio, meningococcus A, pneumococcus, rotavirus, and yellow fever), by introducing and/or continuing their use in 94 low- and middle-income countries, could prevent 24 to 26 million deaths between 2011 and 2020.

Subsequently, WHO developed the 2030 Immunization Agenda (IA-2030), envisioning a world in which all individuals, everywhere and of all ages, fully benefit from vaccinations for their good health and well-being [2]. According to IA-2030, immunization is a critical factor in recognizing the fundamental rights of individuals to enjoy the highest possible degree of physical and mental health, and represents a future investment by creating a healthier, safer, and more prosperous world for everyone. The IA-2030 seeks to harmonize local immunization activity plans at the community, national, regional and global levels, including national governments, regional institutions, global agencies, health professionals, university and research organizations, vaccine developers and manufacturers, the private sector, and society as a whole [2].

Importantly, medical societies can play a role in orientating national or regional vaccination schedules and can be more agile than larger organizations such as PAHO or WHO. For example, in 2020 Argentina considered a recommendation from medical societies and expert groups for full inactivated poliovirus vaccine use [3], and in 2022 the Sociedad Argentina de Pediatria recommended the introduction of hexavalent acellular pertussis (aP)-IPV vaccination for all infants. The aP-IPV vaccine was also recommended recently in Brazil by the Sociedade Brasileira de Pediatria for all preterm babies, and in Colombia it is considered a first step to improve access to modern vaccines. Additionally, evaluations led by regional experts have provided cost effectiveness analyses in favor of the introduction of a pediatric aP-IPV containing hexavalent vaccine in Colombia [4] and the use of IPV in Argentina in infants under 1 year of age [5].

The Latin American Group of Experts on Infant Immunization was established in 2018 to analyze the available evidence and the vaccination coverage in the region, and to support the harmonization, modernization, and optimization of infant vaccination programs in Latin America. This group has developed a range of publications on different aspects of infant vaccination [6–9]. In September 2021, 41 such experts from Argentina, Brazil, Panama, Dominican Republic, El Salvador, Costa Rica, Chile, Colombia, Mexico, Paraguay, Peru, Uruguay, and Venezuela, endorsed by the regional scientific societies SLIPE (Latin American Society of Pediatric Infectious Diseases) and ALAPE (Latin American Association of Pediatrics), met to discuss strategies and agreements that could contribute to increasing regional vaccination coverage to avoid the re-emergence of vaccine-preventable diseases and/or the occurrence of outbreaks. At this meeting, the following items were evaluated:

1. Immunization challenges before and during the COVID-19 pandemic.

2. The status of current immunization programs, particularly infant pertussis and polio vaccination.

3. Possible solutions for overcoming vaccination challenges and achieving regional vaccination coverage targets.

The outcome of these discussions is considered in the following sections, with a focus on the development of recommendations that contribute to increasing regional vaccination coverage to avoid the re-emergence of vaccine-preventable diseases and/or the occurrence of outbreaks.

2. Body

2.1. The impact of COVID-19 on national vaccination programs

Between 2015 and 2019, vaccination coverage in the Americas fell compared to other global regions [10–12]. In addition, the onset of the COVID-19 pandemic, announced by WHO in March 2020 [13], had a further negative impact on vaccination coverage rates, generating risks for the continued control of vaccine-preventable diseases. Consequently, in 2020, according to WHO and UNICEF, 23 million children worldwide were not vaccinated through routine vaccination programs. Of these, 17 million children did not receive any vaccines [14].

As a result, COVID-19 adversely affected health services, increasing the risk of children acquiring vaccine-preventable diseases such as measles, whooping cough, diphtheria, polio, and meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae type b, and Neisseria meningitidis. The number of children not receiving the first dose of essential childhood vaccines was higher in 2020 compared to 2019, increasing by 3.5 million for the first dose of diphtheria, tetanus, and pertussis vaccine (DPT1) and by 3 million for the first dose of measles vaccine [1,14,15]. In the Americas, during 2020, only 82% of children had three doses of diphtheria, tetanus and pertussis (DTP3) vaccine, compared to 91% coverage in 2016 [1,14,15]. Figures 1 and 2 show vaccination coverage in Latin America and the Caribbean region (LAC) countries from 2000-2020, and highlight the general decline since 2015 [16]. The impact on DTP1 and DTP3 is presented in Figures 3 and 4 for countries in the Americas for the period 2018 to 2020, showing the widespread impact of the COVID-19 pandemic, with vaccination coverage maintained during this time in only four countries (Costa Rica, Chile, Cuba, and Nicaragua) [16].

Figure 1. Latin America and the Caribbean Region (LAC) vaccination coverage trends, 2000-2020.

Source: Morice-Trejos et. al [16].

Figure 2. Latin America and the Caribbean Region (LAC) childhood vaccination coverage trends, 2000-2020.

Source: Morice-Trejos et. al [16].

Figure 3. Impact pattern of DTP1 coverage comparing 2018 to 2020 in the Americas.

Source: Morice-Trejos et. al [16].

Figure 4. Impact pattern of DPT3 coverage comparing 2018 to 2020 in the Americas.

Source: Morice-Trejos et. al [16].

Factors associated with the negative impact of the COVID-19 pandemic on national vaccination programs include: decreased demand of vaccination services secondary to the measures adopted to contain the pandemic (including mandatory quarantine with closing of vaccination centers or imposed restrictions to their opening); fear of the general public regarding attending vaccination centers and therefore being in close proximity with others; decreased operational capacity due to budget and human resources reassignments to contain the pandemic; decreased capacity for epidemiological surveillance; and weaknesses in information and reporting systems [15]. Figure 5 shows the impact of factors related to immunization services in LAC countries.

Figure 5. Impact on factors related to immunization services in Latin America and the Caribbean Region (LAC) countries.

Source: Morice-Trejos et. al [16].

2.2. How to overcome the current challenges associated with the re-emergence of vaccine-preventable diseases during childhood?

Since the onset of the COVID-19 pandemic, the impact of reduced availability and/or accessibility of routine vaccines has disproportionately affected low- and middle-income countries, risking the resurgence of vaccine-preventable diseases such as measles [17]. After decades of steadily decreasing rates of a wide range of diseases through control by vaccination, increasing incidences have been observed in recent years. In 2019, there were 21,971 cases of measles in the region, the highest number in the last 20 years [18]. During 2020 and 2021 the incidence of measles remained high but was lower than in 2019 (9,996 and 682 cases, respectively) [18]. In the LAC region, Brazil was the country with the highest number of cases [19]. Furthermore, diphtheria is another disease threatening this region. In March 2021, the Dominican Republic and Haiti registered a new outbreak of diphtheria in school children, adolescents, and adults, adding to cases previously reported during 2020 in Colombia, Brazil, Peru, and Venezuela [20,21]. By October 2021, 4 countries in the region had reported cases of diphtheria: Brazil (1 case), Colombia (1 case), Haiti (18 and 3 deaths), and the Dominican Republic (18 cases and 12 deaths) [20,21].

It will be necessary for countries in the LAC region to work together to overcome challenges and achieve vaccine coverage to protect the most vulnerable populations through the following actions [2,15]:

• Strengthen immunization services from birth and throughout life.

• Improve vaccination of pregnant women to protect both mothers and children.

• Implement immunization catch-up strategies based on WHO recommendations, create new national immuni-zation schedule guidelines, and define catch-up vaccination guidelines in a clear and actionable way.

• Intensify the search for children who have received no vaccine doses and those for whom vaccinations have been missed.

• Restore health services enabling countries to offer routine vaccination safely.

• Expand routine and catch-up vaccination services, particularly in remote communities with the most vulnerable children.

• Help health professionals actively communicate with parents or guardians to clarify their doubts about the efficacy and safety of vaccines, especially in vulnerable populations (eg, those who reject vaccines for cultural or religious reasons).

• Optimize epidemiological surveillance to detect outbreaks and epidemics of vaccine-preventable diseases in a timely manner.

• Improve the registry of vaccine doses administered, prioritizing the nominal dose registry to improve the evaluation of vaccination coverage.

• Instruct health professionals regarding the management and diagnosis of re-emerging diseases.

• Prepare, review, update, and socialize contingency measures for outbreaks.

• Work with scientific medical societies, non-profit organizations, and higher educational institutions (universities that offer health sciences programs) to improve vaccine confidence.

2.3. Whooping cough: what is new for infant Bordetella pertussis vaccination?

2.3.1. Current epidemiological setting

Although confinement due to COVID-19 led to a reduced incidence of some infectious diseases, there is a high risk of the re-emergence of vaccine-preventable diseases with the increasing return to face-to-face activities in the post-pandemic era.

In 2019, a systematic review concluded that the incidence of whooping cough and vaccination coverage in Latin America is highly variable between countries [8]. The high contagiousness of Bordetella pertussis (R0 12-17, which is close to that of the highly contagious measles virus) [8,22], means that vaccination coverage >90% is needed to maintain control of pertussis infection and prevent outbreaks. However, since 2000, few countries have achieved this vaccination coverage rate. Coverage in the second year of life decreased during the COVID-19 pandemic [8,15] due to a range of factors such as the lower frequency of pediatric check-ups for healthy children, fewer families approaching health institutions, as well as parental concern related to the high number of pediatric injections and the associated pain or the possibility of adverse events. Asymptomatic forms of pertussis disease and asymptomatic carriers represent a significant transmission mechanism in the community [8,15].

Probable causes for the persistent outbreaks of whooping cough in the LAC region and the increased reporting of cases in recent years include [8]:

• Greater sensitivity of surveillance systems.

• Changes in the age of onset of pertussis disease: children under 12 months, adolescents, and adults are critical transmission groups.

• Limited duration of immunity after natural infection, as well as after vaccination.

• Suboptimal coverage for both infants (primary series vaccinations) and toddlers (booster vaccination).

• New variants of Bordetella pertussis that could potentially lead to reduced vaccine efficacy.

The heterogeneity in the case definition between countries and vaccination hesitancy are fundamental challenges for controlling pertussis disease and reducing infant morbidity and mortality. It is therefore necessary to review and adjust this definition by age, manage reticent families, and promote confidence in vaccination with the collaboration of the pediatrician, the multidisciplinary team, and the government.

2.3.2. Types of Bordetella pertussis vaccines

A range of Bordetella pertussis vaccines are used in the LAC region. Most countries use whole-cell pertussis (wP) vaccines, although aP vaccines are employed in Costa Rica, Mexico, Panama, and Chile through the use of combination vaccines. In Costa Rica the pentavalent vaccine is used for infant and toddler vaccination, while the hexavalent vaccine is used in Mexico, Panama, and Chile [8,23–25]. In addition, some countries, including Argentina, Brazil, and Colombia, recommend aP vaccines for some high-risk groups [26–28].

Combination vaccines may offer different advantages, including [29,30]:

• Fewer injections per visit.

• Better experience for the child at the time of vaccination and greater compliance with vaccination schedules.

• Improved vaccination coverage.

• Reduced use of supplies such as syringes and needles.

• Simplified implementation of vaccination programs.

• Improved equity in vaccine access.

A difference in the frequency and severity of adverse events is associated with wP-containing vaccines compared to those with aP antigens, with increased reactogenicity of wP vaccines reported in several countries. Chile switched to the hexavalent vaccine with aP antigens due to the incidence of serious adverse events associated with the pentavalent wP-containing vaccine, particularly in premature infants (4-fold increase with wP-containing vaccines compared to aP-containing vaccines) [26]. A recent publication showed a 23% and 36% decrease in adverse events during 2018 and 2019, respectively, after the introduction of the hexavalent aP vaccine in Chile (2, 4, 6, and 18 months of age) [31]. In Uruguay, a higher incidence of hypotonic hyporesponsive episodes (HHE) associated was observed for one wP pentavalent vaccine, showing that different wP-containing vaccines can have different reactogenicity profiles. In Vietnam, a vaccination program was put on-hold after a number of adverse events and hospitalizations following vaccination of children using a wP-containing vaccine [32]. Also, in El Salvador there was a disproportionate number of febrile seizures following vaccination with a wP-containing pentavalent vaccine in 2019, suggesting the existence of a safety signal [33].

Another drawback of the wP-containing vaccine is the diversity of manufacturers, and the likelihood of heterogeneity in manufacturing controls. For example, the Brazilian regulatory agency (ANVISA) detected a quality deficiency in a pentavalent wP vaccine and suspended the marketing authorization license, leading to vaccine shortages and reduced coverage for the primary series vaccination before the COVID-19 pandemic [34].

Parental satisfaction is an essential factor to ensure adherence to vaccination schedules. In a study carried out in Chile on the perception of parents concerning the use of wP and aP vaccines, greater satisfaction and desire to continue with the subsequent doses of the vaccine after the first dose was reported for the aP vaccine than for the wP vaccine [35]. This is likely to result in improved vaccination coverage for aP-containing vaccines; in Chile, vaccination coverage rates for DTP3 and DTP4 of 90% (latter part of 2018) and 80% (beginning of 2019) increased by 11% and 12%, respectively, by the end of 2019 following the introduction of an aP-containing hexavalent vaccine for infant primary series and toddler booster vaccination.

The WHO Strategic Advisory Committee on Immunization (SAGE) has proposed some innovation priorities that could have a significant impact on national immunization programs [36], including:

• Coordination of new immunization strategies from start to finish, necessary to advance on lessons learned in the prioritization of innovation and the preparedness of countries to adopt such innovations.

• Purchasing innovative products at an ideally neutral cost to have a positive impact on vaccination programs. However, if the cost is higher than the existing vaccine, evidence of cost-efficiency and economic impact is necessary to rationalize the acquisition and eventually establish new cost-effective evaluation models.

In a cost-minimization analysis study carried out in Chile, before the introduction of the hexavalent aP-containing vaccine, it was concluded that its inclusion would generate additional acquisition costs but that these would be partially offset by better logistics and a reduction in adverse events associated with current vaccines as well as additional benefits to vaccination programs [37]. Argentina, Peru [38], and Colombia [4] have developed and are carrying out similar studies, which show the relevance of hidden costs (improved logistics, fewer adverse events, and simplified execution of vaccination programs) in vaccine investment beyond the price or net cost of the vaccine.

Concerning the B. pertussis vaccine, it is important to consider the importance of recovering regular vaccination schedules after the COVID-19 pandemic, vaccinating pregnant women, vaccinating all children with the first DTP dose between 6 and 8 weeks of age, and facilitating access to up-to-date and timely information. In addition, the availability of data on vaccination coverage, morbidity, lethality, and other epidemiological indicators for pediatric and the healthcare teams enables the development of action policies that allow them to deal adequately with the clinical situations that may arise.

In conclusion, the prevention of whooping cough is a priority in infants. The focus of the vaccination strategy should be on pregnant women, the primary immunization series, and boosters throughout life.

To maintain control over pertussis disease, it is necessary to:

• Guarantee consistent coverage above 90% at both regional and local levels.

• Address incomplete vaccination schedules.

• Consider utilizing combination aP-containing vaccines that, given their better tolerability profile, favor adherence to immunization and catch-up schedules and simplify national vaccination programs.

• Work on surveillance and case definition, and facilitate access to epidemiological information.

• Develop and update institutional and national immunization guidelines.

• Work as interdisciplinary groups.

• Prepare pediatricians and general practitioners to establish strategies that allow the recovery of vaccination schedules.

2.4. Polio: infant vaccination, what is new?

The silent circulation of polio in the Americas is probably due to viruses derived from the oral polio vaccine rather than wild viruses. The risk of polio due to circulating vaccine-derived polioviruses (cVDPVs) is associated with a range of factors, including the use of the attenuated oral vaccine, low vaccination coverage, inadequate epidemiological surveillance, lack of environmental surveillance, and non-compliance with the requirements and indicators of poliovirus containment [6,39,40]. Consequently, it is recommended that healthcare systems are adapted as applicable to implement new polio elimination strategies, including:

• Introduce complete schedules with inactivated polio vaccine, reducing the risk the emergence of cVDPV and iVDPV (VDPVs in immunosuppressed patients) through stand-alone vaccines (ie, those not combined with other antigens) and/or combined with other antigens, the latter having the advantage of reducing the number of injections in the primary and booster schedule and improving rates of vaccination coverage and compliance.

• Reduce complexities related to the introduction of new vaccines.

• Increase vaccination coverage and update polio vaccination.

• Develop activities designed to increase vaccine confidence.

• Improve vaccination resources.

• Accept COVID-19 vaccine co-administration with the regular schedule for children, based on the recommendations of international and regional entities.

According to polio-free regions, SAGE has developed a recommendation for vaccination in the fight against polio and for the countries of the Americas to consider switching fully to inactivated poliovirus vaccine (IPV) schedules [41]. According to SAGE, if schedules begin as early as 6 weeks after birth, complete regimens with conventional IPV (cIPV) are preferable over fractionated IPV (fIPV) regimens. The basis of the recommendation is the evidence that 2 doses of fIPV have similar immunogenicity to 2 doses of cIPV when vaccination is started after week 14 (3.5 months of age) and with an interval between the 2 doses greater than 16 weeks [36]. Regimens of cIPV and fIPV that start at six weeks have shown a similar frequency of seroconversion, but antibody titers are lower with the fIPV vaccine with a potential impact on long-term protection against polio, and also the logistics for fIPV implementation are more complex [40].

The Americas have schedules that start at two months of age, and the recommendation is to start catch-up strategies as early as six weeks. Schedules with cIPV would be the best choice for a region free of wild polio that seeks to maintain the elimination and reduce the risk of poliovirus derived from the oral polio vaccine, having a sufficient supply of either stand-alone IPV or IPV combined with other antigens.

2.5. Health value: new opportunities

The current trend in health economics is to compare costs and benefits, considering all relevant decision-making factors. As well as the usual costs associated with an intervention (eg, the acquisition, implementation, and distribution of a new vaccine) it is important to fully analyze the hidden costs for each dose of vaccine in a vaccination program.

A study was conducted to determine the financial impact of the introduction of the hexavalent aP-containing vaccine in Chile. Three types of costs were included in the analysis, which used the wP-containing vaccine as the comparator: acquisition costs, adverse event costs, and programmatic costs. The higher reactogenicity of the wP vaccine compared to the aP vaccine resulted in an annual cost saving of almost 9 million dollars associated with the aP vaccine [37].

2.6. Maternal vaccination: when to vaccinate pregnant women?

Maternal vaccination is one of the most critical health interventions for disease prevention and improving maternal and neonatal health. According to WHO guidelines, based on a risk-benefit assessment, pregnant women should be vaccinated to protect both themselves and newborns. In addition, maternal vaccination can potentially provide a public health strategy for preventing diseases such as influenza, whooping cough, and COVID-19 [42,43].

Vaccines recommended in pregnancy include tetanus (Td, TT), inactivated influenza (IIV) and acellular pertussis (Tdap). These are all inactivated vaccines and are recommended because they are beneficial to the mother and fetus and pose a low risk to both. Live vaccines are generally contraindicated during pregnancy [43]. Administration of the SARS-CoV2 vaccine is essential in the ongoing COVID-19 pandemic situation [44–46].

The timing of vaccination during pregnancy should aligned with current national recommendations. Additionally, vaccination may be necessary for each pregnancy depending on the type of disease and vaccine.

New vaccines, still under investigation, can benefit pregnant women and newborns; such vaccines include Group B Streptococcus, malaria, Zika, and cytomegalovirus (CMV) vaccines. Recently, Centers for Disease Control and Prevention recommend an respiratory syncytial virus vaccination for use during pregnancy.

3. Recommendations and action plans proposed by LAC experts on implementing local and regional short-, medium-, and long-term measures to reverse the downward trend in vaccination coverage

The following sections provide recommendations and action plans to improve vaccination coverage in the LAC regions. Given the concerns regarding low vaccination coverage in addition to the evident and current risk of the re-emergence of vaccine-preventable diseases, it is recommended that such an action plan be implemented immediately, rather than in the medium- or long-term. Scientific societies should recommend experts to be either permanent or advisory members of the national immunization commissions of health agencies, to help establish public-private partnerships for the implementation of action plans to increase vaccination coverage rates in the LAC region and recover schedules of unvaccinated children or partially vaccinated.

Maintain and strengthen epidemiological surveillance systems - information collection and analysis

• Detection, diagnostic capacity in laboratories, and reporting mechanisms should be maintained and strengthened for early detection and control of outbreaks.

School attendance

• School attendance is a priority measure for children and represents a tool in the control and updating of vaccination schedules. This should be associated with adequate measures to prevent the risk of re-emergence of vaccine-preventable diseases, outbreaks or epidemics of diseases, even if they have previously been controlled.

Strengthen vaccine education

• Vaccine education and training for health professionals: faculties of medicine, nursing and pharmacy.

• Develop complementary educational sessions on vaccination (eg, vaccination in regular schedules, catch-up strategies), targeted to all involved in the vaccination process in primary care. These include: health professionals, students, vaccinating nurses, pediatricians, and administrative staff. These sessions must be coordinated by vaccination experts, with the support of scientific societies as allies of education and public health strategies.

Improve access to vaccination and seek vaccination equity to achieve homogeneous coverage among countries, including migrant populations

• Actively search for populations facing access barriers to vaccination services.

• Offer extended-hours vaccination centers and extramural vaccinations (drive-through, schools, campaigns that include the entire family group) as catch-up vaccination strategies.

• Use complete schedules with IPV to reduce the risk of VDPV.

Improve the operational capacity and execution of regular vaccination for children

• Implement action plans to address vaccine shortages and avoid interruptions to routine vaccination programs.

• Improve the availability of additional personnel to execute regular vaccination programs, rather than focusing resources on the implementation of the COVID-19 program.

• Develop regulations and recovery or catch-up strategies by age group, executable for primary care and the public-private system.

• Improve the inclusion and commitment of primary care personnel, who are essential participants in the execution of national vaccination programs.

Strategic alliances to invest in vaccines as a public health strategy

• Public-private partnerships to improve coverage.

• Multimodal view of vaccination coverage (public institutions, providers, non-governmental organizations).

• Strategic alliances with private vaccination centers to support regular vaccination programs.

• Favor the introduction of combination vaccines in vaccination schedules to improve coverage, optimize vaccinations, and promote vaccination in all populations.

Encouraging confidence in vaccination through communication

• Prepare guidelines for the management of families who are reluctant to vaccinate.

• Define regional causes for reluctance to vaccinate children.

• Understand the use of social networks in disseminating messages to the general population opposing vaccination: disinformation, infodemics.

• Develop an effective communication strategy, supported by scientific evidence, but capable of emotional impact that can counteract reluctance to vaccination and infodemics.

• Support from communicators to expand messages about the benefit of a vaccination plan. Training health communicators. Actions with influencers (networks) on vaccination strategies.

• Alliances with non-governmental organizations to strengthen communication aimed at the general population and present it to vaccination decision-makers.

• Support regional and local scientific societies as official spokespersons about information related to vaccination programs.

Strengthen the role of medical groups in vaccination strategies at national and regional levels

• Sharing of successful vaccination experiences by medical and scientific societies at national and regional levels.

• Local and regional level representation of pediatrics, infectious diseases, vaccinology, medical associations and epidemiology scientific societies (PAHO) within the National Immunization Technical Advisory Group (NITAG) structures.

• Harmonization of NITAGs to allow response to health agencies from the technical-scientific perspective.

• Workgroups established for vaccine-preventable diseases with regional representation (PAHO) to support regional and local recommendations and local suggestions, based on evidence and experience.

• Plan a consensus on vaccination in the LAC region in which there is a real commitment to improving coverage.

4. Conclusion

Medical societies have regularly provided valuable recommendations to orientate and modernize vaccination schedules in recent years, leading to the introduction of new vaccines such as Hib, IPV, and varicella to better protect children. Such recommendations are often in advance of more widespread regional or global recommendations from organizations such as PAHO or WHO.

With the academic endorsement of SLIPE and ALAPE, the Group of Experts on Infant Immunization for Latin America analyzed the immunization challenges before, during, and after the COVID-19 pandemic and the current status of vaccination programs in the LAC region. An emphasis was placed on infant pertussis and polio vaccination, and possible solutions were proposed to overcome the challenges and achieve the target vaccination coverage in the region. The group developed a series of general recommendations that it hopes will be disseminated and followed in the LAC region to combat the re-emergence and/or the occurrence of outbreaks of vaccine-preventable diseases.

5. Expert opinion

The coverage of certain pediatric vaccines in the Americas fell sharply in the years preceding the COVID-19 pandemic, more so than in other global regions. Additionally, pre-existing regional and country-level disparities in infant vaccination coverage and access were exacerbated by negative aspects of the COVID-19 pandemic that limited the implementation of national vaccination programs. In the post-pandemic era, solutions are needed to overcome the challenges associated with the resurgence of vaccine-preventable diseases in childhood, with pertussis and polio being particular threats. As well as global and regional plans from organizations such as WHO and PAHO, medical societies have an important role to play in facilitating and orientating discussion and recommendations at the regional and national levels. Persistent outbreaks of whooping cough in the Latin America and Caribbean region have been linked to suboptimal primary series and booster vaccination of infants, and it is necessary generally to promote confidence in vaccination programs. Vaccine hesitancy can be linked to specific aspects such as perceptions of vaccine safety, eg, increased reactogenicity of whole-cell pertussis vaccines compared to those containing acellular pertussis antigens, as well as more general concerns that may be linked to misinformation. Additionally, real concerns of circulating vaccine-derived polioviruses linked to the use of the oral polio vaccine can be addressed by the more widespread use of inactivated polio vaccines. The equitable use of infant and toddler pentavalent and hexavalent vaccines that contain diphtheria, tetanus, acellular pertussis, inactivated polio, hepatitis B, and Haemophilus influenzae type b antigens is crucial to address the resurgence of pediatric vaccine-preventable diseases. Such vaccines have been shown to be highly effective and cost-effective. Furthermore, maternal vaccination against diseases such as influenza and whooping cough is key to providing protection to infants during the period of susceptibility in the first months of life. Strategic alliances between public institutions, vaccine providers, and non-governmental organizations should be created to oversee the implementation of recommendations such as these, which may be proposed initially by local groups of medical experts. Consensus reached by such groups can provide the impetus for rapid implementation at the regional or country level, and in advance of the release of global guidance. Strengthened epidemiological surveillance is vital to monitor the effect of such measures on the incidence of vaccine-preventable diseases in children. Regular and accurate reporting of incidence rates of common childhood diseases should be used to quantify the implementation of recommendations. It is hoped that clear improvements in childhood morbidity and mortality will be demonstrable in 5 years and 10 years. Such information should be disseminated in the public domain to combat vaccine hesitancy at the societal level and promote the benefits of robust pediatric vaccination programs in terms of reduced incidence of vaccine-preventable childhood diseases.

Article highlights

• Vaccination coverage has fallen sharply in recent years, which has been made worse by the impact of the COVID-19 pandemic.

• Low rates of vaccination lead inevitably to the resurgence of vaccine-preventable diseases.

• The global resurgence of whooping cough and poliomyelitis are of particular concern, with increased incidence linked to a range of factors, including inequities in vaccine access, suboptimal infant vaccine coverage, vaccine hesitancy, migration, and circulating oral polio vaccine-derived polioviruses.

• Medical societies, such as the Latin American Group of Experts on Infant Immunization are important in the development of recommendations to support the harmonization, update, and optimization of infant vaccination programs at the regional and national levels.

• Recommendations to overcome the challenges associated with the resurgence of vaccine-preventable childhood diseases in Latin America and the Caribbean include strengthening surveillance systems, improving school attendance, advancing vaccine education and confidence, striving for vaccination equity, widening operational capacity, creating strategic alliances, and strengthening the role of medical groups.

• The use of pentavalent or hexavalent combination pediatric vaccines allows for protection against 5 or 6 common childhood diseases in a single injection, and leads to improved vaccine coverage, compliance and equity, reduced use of supplies, and simplified implementation of vaccination programs.

• Expert recommendations should be disseminated in Latin America and the Caribbean to combat the re-emergence and/or the occurrence of outbreaks of vaccine-preventable diseases.

Declaration of interests

ML Ávila-Agüero declares consulting fees (consulting and advisory boards) from Sanofi, Pfizer, MSD, and Johnson & Johnson, and honoraria from Sanofi, Pfizer, and MSD for lecturing or chairing events. J Brea-del Castillo declares consulting fees (consulting and advisory boards) from Sanofi and MSD, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Pfizer, MSD, and Sanofi, and leadership or fiduciary role in other board, society, committee or advocacy group (unpaid) for the Latino American Pediatric Infectious Diseases Society and the Dominican Society of Vaccinology. LH Falleiros-Arlant declares payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi, MSD, Sociedad Latinoamericana de Infectologia Pediatrica (SLIPE), and Brazilian Society of Inmunization (SBIm), support for attending meetings and/or travel from Sanofi, MSD, SLIPE, and SBIm, participation on a Data Safety Monitoring Board or Advisory Board for Sanofi, SLIPE, and SBIm, leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid, for Sanofi, SLIPE, SBIm, and Technical Committee of Certification of Polio Eradication (Brazilian Ministry of Health). E Berezin declares payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Pfizer and Sanofi, payment for expert testimony from Pfizer and MSD, and support for attending meetings and/or travel from Sanofi and MSD. C Torres Martínez declares consulting fees from Sanofi, Pfizer, and MSD (consulting and advisory boards) and Medscape (consulting), payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi, Pfizer, and MSD, and support for attending meetings and/or travel from Pfizer and Sanofi. EL Lopez declares consulting fees from Sanofi, Pfizer, and MSD (consulting and advisory boards) and Medscape (consulting), payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi, Pfizer, and MSD, and support for attending meetings and/or travel from Pfizer and Sanofi. A Laris-Gonzalez declares a one-time payment (consulting fee) for the current work, support for attending meetings and/or travel from Sanofi. JPTT declares payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi. E López-Medina declares grants or contracts from Sanofi, GSK, and Janssen, and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Sanofi, MSD, GSK, Pfizer, and Takeda. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or material discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Author contributions

All authors made substantial contributions to the development of the work, the analysis and interpretation of the data, reviewed it critically, approved the final version to be published, and are fully accountable for all aspects of the work.

Acknowledgements

Dr Andrew Lane (Lane Medical Writing) provided medical writing assistance, funded by Sanofi, in the preparation and development of the manuscript in accordance with the European Medical Writers Association guidelines and Good Publication Practice.

Additional information

Funding

This manuscript was funded by Sanofi.