ABSTRACT
Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is still an enormous threat to global health and the economy. Although China has adopted effective measures to control the outbreak, there is still a risk of local transmission from imported cases. Meanwhile, considering the high mortality rate and rapid spread of the disease, a safe and effective vaccine is urgently needed to control the pandemic. With COVID-19 vaccines becoming available to the population, it has become important to know about their acceptance in the population. This is important to enable high vaccination coverage rates and reflects the demand within the general population. An cross–sectional survey was conducted during October 2020 in Shanghai using a well-designed questionnaire, which aimed to evaluate the acceptability of COVID-19 vaccines and to identify the factors affecting its acceptability among working-age adults in Shanghai, China. We found that the acceptability of COVID-19 vaccines was high in work-age adults in Shanghai, China. The factors affecting the acceptability of vaccination identified in this study can provide guides to increase COVID-19 vaccine acceptability in future.
Introduction
The novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is still an enormous threat to global health and the economy.Citation1–3 By March 2021, SARS-CoV-2 has infected more than 120 million people worldwide and resulted in more than 2 million deaths.Citation4 China has taken effective measures to control the outbreak and very few people were infected.Citation5
Shanghai is the largest and most developed city in China with approximately 24 million of people, and the anti-epidemic stance taken by Shanghai has proved effective as the city has had no indigenous COVID-19 cases for a long period of time.Citation5 However, as travel to China from foreign countries increased, imported cases of COVID-19 also increased sharply.Citation6 Shanghai as one of the port cities with the largest number of annual entry population, is now facing the risk of local transmission from the imported cases.
Since COVID-19 has a basic reproductive number that is currently estimated to be in the region of 2.5–3.0,Citation7,Citation8 the community’s immunity levels need to reach at least 70% in order to stop the COVID-19 pandemic. Therefore, a safe and effective vaccine is urgently needed to control this pandemic. With COVID-19 vaccines becoming available, occupational populations, such as those in the high-risk sectors of cold-chain food or public transportation and age group 18–59 years, have been made a priority for vaccination. It is thus important to understand its acceptance and demand in these population groups in order to achieve high vaccination coverage rates. This study aimed to evaluate the acceptability of COVID-19 vaccines and to identify correlates of acceptability among working-age adults in Shanghai, China, in order to develop immunization strategies and programs against COVID-19.
Methods
Study design
In this cross-sectional study, a self-administered, anonymous questionnaire was distributed to a convenient sample from community health service centers in Shanghai from October 2020 to November 2020. People who visited the community health service centers and were willing to participate in the study filled in the questionnaires. The eligibility criteria included being age 18 or older and being fluent in Chinese. As per the sample size calculation formula,Citation9 n = Zα2 pq/d2, n was the required sample size and p the rate of the COVID-19 vaccine acceptance. We used 91%, which was the rate obtained from other studies performed in China.Citation10 Therefore, with q = 1-p, q was 9%. Z was the standard normal distribution boundary value, and with α = 0.05 and Zα = 1.96, d, the tolerance error was 0.01, and n was calculated to be 3147.
Questionnaire
The design of the self -administered questionnaire was based on previous studies that evaluated vaccine acceptance for emerging infectious diseases.Citation11,Citation12 The contents of the questionnaire included: (1) socio- demographic factors: gender, age, ethnicity, education, family income, and health insurance; (2) health-related characteristics: perceived self-rating health, the severity of COVID-19, the extent of that the family burden increased by COVID-19, and the extent of worrying about COVID-19; (3) a knowledge section (six questions, each correct answer was given 1 point and each incorrect one was given 0 point [total scores: 1–2 = low knowledge, 3–4 = middle knowledge, 5–6 = high knowledge]): awareness of COVID-19, the pathogen, the route of transmission, the symptoms, and the susceptibility of the population; and (4) acceptance of the COVID-19 vaccination: we assessed the participants’ vaccine acceptability by asking whether they were willing to get a COVID-19 vaccine if it was free.
The questionnaire was designed and adjusted to investigate the participants’ knowledge, attitude, and practices. A pilot test of the first draft of the questionnaire took place in two primary health centers in which the ability to complete the questionnaire was assessed. The time spent on the completion of the questionnaire was approximately 10–15 min. The results of the pilot test were used to further modify the questionnaire.
Statistical analysis
SPSS 17.0 (SPSS Inc, Chicago,IL) was used for the data analyses. Descriptive statistics were performed to describe the socio-demographic characteristics, perceptions, and acceptance of the COVID-19 vaccine. The Chi-square test was used for the univariate analysis. A multivariate logistic regression was then performed between the vaccine demand group and vaccine delay group in order to identify the influencing factors of vaccination acceptance (immediate or delayed acceptance), with the odds ratios (ORs), standard errors (SEs) and 95% confidence interval(CIs) being calculated.
Results
Demographic characteristics
A total of 5132 adults from all 16 districts participated in our study and completed the survey; 4962 questionnaires were qualified and valid. There was a 96.7% valid questionnaire return. The highest number of participants were the Han (4,925/4,962; 99.3%) and had at least some college education (3,989/4,962; 80.4%), while 78.0% (3,868/4,962) were of the resident population (). Of these, 3995 were women, accounting for 80.5%, and 967 were men, accounting for 19.5% with 63.2% (3,136/4,962) being of the ages between 30 and 44 years old. The majority (2,762/4,962; 55.6%) had a total household income ranging from CNY 50,000 to CNY150,000.
Table 1. Characteristics of the survey participants from Shanghai city
During the survey, most of the participants (4,876/4,962; 98.3%) had some type of health insurance, and 98.2% (4874/4,962) indicated that there were no confirmed or suspected cases in their communities. The majority of the participants (3790/4962, 76.4%) agreed that COVID-19 was a cause of serious illness, while 97.3% (4828/4962) reported that the COVID-19 pandemic “very largely” or “largely” increased their family burden. In addition, 30.7% were “highly worried” about getting COVID-19.
Knowledge and disease perception toward infection
As shown in , a total of 91.0% of the participants knew that the pathogen that caused COVID-19 was SARS-CoV-2, 98.9% and 99.0% knew about the main mode of transmission and the symptoms of COVID-1, respectively, while 63.8% were able to identify the incubation period of COVID-19. In addition, 70.0% answered that a specific drug therapy for COVID-19 did not exist and 72.9% reported that all groups were susceptible.
Table 2. Knowledge and disease perceptions toward infections
Of the participants included in the study, 0.3% (16/4962) had a knowledge score of six, 58.1% (2881/4962) five, 37.4% (1856/4962) four, 4.2% (206/4962) three, and 0.1% (3/4962) two. The majority of the participants (58.4%) had a good level of knowledge (knowledge score ≥ 5).
Acceptability of COVID-19 vaccine and associated variables
Overall, 84.6% (4200/4962) of the participants would like to be vaccinated if the COVID-19 vaccine were successfully developed and approved in the future. The Chi-square test results showed that, among the sociodemographic variables, gender, age groups, education, resident or migrant population and income were significantly associated with the acceptability of the COVID-19 vaccine. Among the health-related characteristics, self-rating health, perceived severity of COVID-19, perceived extent of the increase in the family burden as a result of COVID-19, and COVID-19 related knowledge were correlated with the acceptability of the COVID-19 vaccine ().
Table 3. Association of factors and COVID-19 vaccine acceptability
The multivariable analysis (), showed that the respondents were more likely to be willing to get a COVID-19 vaccine if they were female (OR = 1.520, 95%CI, 1.135–2.033), or older (OR = 1.272, 95%CI, 1.244–1.302). Participants were less likely to be willing if they had an income of >200,000 (OR = 0.408, 95%CI, 0.184–0.904), a college education level of college or some college education (OR = 0.692,95%CI, 0.494–0.969), or a master’s degree of or above (OR = 0.561, 95%CI, 0.386–0.817). Participants were also less likely to be willing if they reported lower levels of perceived severity of COVID-19 infections (OR = 0.145, 95% CI: 0.051–0.408), and had a higher level of knowledge of COVID-19 (OR = 0.023, 95% CI:0.05–0.093) ().
Table 4. Multivariate analysis of acceptability of participants of the COVID-19 vaccine
Among the 762 participants who were not willing to receive the COVID-19 vaccine, 3.5% (27/762) indicate that it was unnecessary, 27.8% (278/762) doubted its the effectiveness, and 66.1%(504/762) doubted its safety.
Discussion
Vaccines are best way to prevent infectious disease and the development of COVID-19 vaccines is proceeding rapidly. Some vaccines have already been approved for emergency use. Since October 2020, Shanghai commenced with an emergency vaccine program for the high-risk groups, which were populations with a higher risk of SARS-CoV-2 infections. Understanding vaccine acceptance in this population is important, because such information is useful for forecasting vaccine utilization and also identifying strategies for improving acceptability. We found that 84.6% of the participants from Shanghai would be willing to receive a COVID-19 vaccine, which was lower than data made from China during the pandemic period.Citation9 We carried out this investigation between October 2020 and November 2020, while the epidemic was under control and the COVID-19 vaccine was approved for emergency use in China. In our study, we found that COVID-19 vaccine acceptance was associated with the perception of disease risk. Some people were not willing to be vaccinated because they did not think that there was a risk of infection. However, the acceptability of COVID-19 vaccine among the population aged 18–59 years in Shanghai was higher than in other countries.Citation13,Citation14
Vaccine acceptability was lower among several socio-demographic groups, including participants who were male, younger, and had a high level of education and income. Older subjects were more willing to receive the COVID-19 vaccine, which may have been due to the relatively high incidence and fatality rate of COVID-19 in older persons.Citation15,Citation16 The participants with higher levels of education were significantly less willing to vaccinate while those who had a higher knowledge of COVID-19 were less likely to accept the vaccine. This may have been due to their receipt of more social network and professional information, as well as their greater concerns about the effectiveness and side effects of COVID-19. This may have influenced their decision to vaccinate and to promote the vaccine to patients.
In our study, it was also observed that men are more willing to receive the COVID-19 vaccine than women, which may have been due to men’s higher risk perceptions of the disease than women, and it was also reported that the fatality rate of COVID-19 in men was higher than that in women.Citation17,Citation18
Another finding was that those who had a higher perceived risk of being infected with COVID-19 were more likely to accept the vaccine. Previous studies have found that perceived risk or perceived susceptibility to an infection was associated with positive support for vaccination.Citation19–21 Another study also found that a high perceived risk was associated with COVID-19 vaccine acceptance among general community members in Saudi ArabiaCitation22 and among health care workers in China.Citation23 Shanghai’s epidemic prevention and control efforts have been very effective, with no local cases occurring for a long period of time.
This was the first study to investigate the acceptance of the COVID-19 vaccination among a large population in Shanghai city during the period of regular epidemic prevention and control, which provided information for the ongoing monitoring of the acceptance of COVID-19 vaccination by the public. At present, Shanghai is promoting the COVID-19 vaccine among the working-age population. Our study investigated the influencing factors of pandemic vaccination acceptance, such as socio-demographic characteristics. The exploration of the factors influencing vaccination was useful in the identification of priority groups that need special attention.
This study had certain limitations. First, the participants were selected using a convenience sampling which could have led to biased results. Second, the information was self-reported. This was subjective and could also have led to bias. Third, there was a lack of assessment of other factors that may have contributes to the vaccine acceptability of the participants.
In conclusion, the acceptance of a COVID-19 vaccine was high among the working-age population in Shanghai city during emergency use phase of vaccinations. Our study can provide guidance on strategies to increase COVID-19 vaccine acceptability, in the future. Our results have highlighted that demographic characteristics, such as gender, education and income, influence the participants’ acceptance of vaccination. Meanwhile, the perceived risk of being infected with COVID-19 also plays a role in the acceptability of a COVID-19 vaccine. These finding can help to attain high vaccination rates. We should continue to monitor temporal changes in acceptance with the increasing use of COVID-19 vaccine.
Disclosure of potential conflicts of interest
No potential conflicts of interest were disclosed.
Acknowledgments
The authors thank all the participants for their support for the investigation.
Additional information
Funding
References
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