Understanding hesitancy with revealed preferences across COVID-19 vaccine types

COVID-19 vaccine hesitancy: Meaning relations between responses in an epidemiological study and twitter messages

BACKGROUND

Vaccine hesitancy is a concerning public health issue, further amplified during the COVID-19 pandemic. Social media is an important player in this context, promoting the dissemination of both information and misinformation. Qualitative studies analyzing the meaning of social media contents in correlation with epidemiological data are scarce, and could aid our understanding of social media's impact on vaccine hesitancy.

METHODS

In this study, we identified open-ended responses on reasons to refuse the COVID-19 vaccine collected in an epidemiologic study, and analyzed meaning relations with Twitter posts according to theme categories using a qualitative approach.

RESULTS

Among responses to open-ended questions on motivations for refusing the COVID-19 vaccine, we identified and analyzed five theme categories: 1. individuality; 2. fear of adverse events/distrust in vaccine safety; 3. political ideologies/aversion to recommendations issued by the State; 4. skepticism about vaccine efficacy; and 5. refusal of non-natural products or interventions. We observed a close correspondence between open-ended responses in the epidemiological study and Twitter posts in all 5 theme categories. The highest outreach of Twitter posts was observed for those in the "individuality" and "fear of adverse the events/distrust in vaccine safety" theme categories.

CONCLUSIONS

Our study suggests that social media interactions can perpetuate misinformation and hesitant attitudes about vaccines. Social media algorithms can intensify ideologic isolation, and strategies to promote the dissemination of tailored health information among social media users should be implemented to promote an overall understanding of health, particularly those concerning the collective wellbeing.

When reality knocks on the door. The effect of conspiracy beliefs on COVID-19 vaccine acceptance and the moderating role of experience with the virus

RATIONALE

Prior research suggests that belief in conspiracy theories can reduce the willingness of individuals to get vaccinated during the COVID-19 pandemic. Examining factors that may moderate this negative effect is an important area of research.

OBJECTIVES

The objective of this study was to examine the relationship between vaccine uptake and two types of conspiracy beliefs (COVID-19 and vaccine-related) and the moderating role of direct and indirect experiences with the coronavirus.

METHODS

We draw on nationally representative survey data collected in Hungary in January 2022 (N=1000, 47% male, 53% female; mean age 49.6 years). Structural equation models and multi-group analysis were performed.

RESULTS

Conspiracy beliefs were strongly associated with vaccine uptake, however, both direct and indirect experiences with the virus moderated the effect of conspiracy beliefs. Individuals who experienced a serious infection or reported a close person being infected by the virus developed severe symptoms or even died were less likely to take conspiracy theories seriously when deciding about their own vaccination. In two out of the four tested moderation effects, a negative experience with the virus reduced the negative effect of conspiracy beliefs.

DISCUSSION

Our findings demonstrate that personal or close real-life experience with severe COVID-19 infection can significantly mitigate the impact of conspiracy beliefs on vaccine hesitancy, highlighting the importance of real-life evidence in overcoming misinformation and increasing vaccine uptake. Nevertheless, it is important to mention that our results are preliminary, and future studies need to replicate the findings and test their robustness.

Socioeconomic determinants and reasons for non-acceptance to vaccination recommendations during the 3rd - 5th waves of the COVID-19 pandemic in Hungary

BACKGROUND

In Hungary, although six types of vaccines were widely available, the percentage of people receiving the primary series of COVID-19 vaccination remained below the EU average. This paper investigates the reasons for Hungary's lower vaccination coverage by exploring changing attitudes towards vaccination, socio-demographic determinants, and individual reasons for non-acceptance during the 3rd - 5th pandemic waves of COVID-19.

METHODS

The study's empirical analysis is based on representative surveys conducted in Hungary between February 19, 2021, and June 30, 2022. The study used a total of 17 surveys, each with a sample size of at least 1000 respondents. Binomial logistic regression models were used to investigate which socio-demographic characteristics are most likely to influence vaccine hesitancy in Hungary. The study analysed 2506 open-ended responses to identify reasons for vaccine non-acceptance. The responses were categorised into four main categories and 13 sub-categories.

RESULTS

Between the third and fifth wave of the pandemic, attitudes towards COVID-19 vaccination have significantly changed. Although the proportion of vaccinated individuals has increased steadily, the percentage of individuals who reported not accepting the vaccine has remained almost unchanged. Socio-demographic characteristics were an important determinant of the observed vaccine hesitancy, although they remained relatively stable over time. Individuals in younger age groups and those with lower socioeconomic status were more likely to decline vaccination, while those living in the capital city were the least likely. A significant reason behind vaccine refusal can undoubtedly be identified as lack of trust (specifically distrust in science), facing an information barrier and the perception of low personal risk.

CONCLUSION

Although compulsory childhood vaccination coverage is particularly high in Hungary, voluntary adult vaccines, such as the influenza and COVID-19 vaccines, are less well accepted. Vaccine acceptance is heavily affected by the social-demographic characteristics of people. Mistrust and hesitancy about COVID-19 vaccines, if not well managed, can easily affect people's opinion and acceptance of other vaccines as well. Identifying and understanding the complexity of how vaccine hesitancy evolved during the pandemic can help to understand and halt the decline in both COVID-19 and general vaccine confidence by developing targeted public health programs to address these issues.

Sociodemographic determinants of vaccination and willingness to pay for COVID-19 vaccines in Hungary, results of a cross-sectional online questionnaire

BACKGROUND

Several different coronavirus disease (COVID-19) vaccines were authorized and distributed all over the world, including Hungary, but vaccination rates and acceptance of the different vaccines varied through 2021 and subsequent years. In Hungary Western vaccines and the Chinese and Russian vaccines were available in early 2021. Understanding preference and willingness to pay (WTP) for the COVID-19 vaccine could provide information for policy decision making to control the COVID-19 pandemic. We aimed to assess the socio-demographic factors influencing the COVID-19 vaccination and to analyse individual preferences for the available COVID-19 vaccines in Hungary.

METHODS

A cross-sectional online questionnaire survey was conducted between 25-05-2021 and 08-06-2021 exploring the vaccine acceptance and WTP for vaccination in the Hungarian general population. To assess the preferences towards the different vaccines available in Hungary at the time of the study, we used a multi-step WTP task.

RESULTS

Altogether 2,000 respondents filled out our survey, with the average age of 49.1 (SD = 15.3), out of whom 370 respondents (18.5%) stated that they already had a COVID-19 infection. Age above 65 years, male gender, higher level of education, higher income and residence in the capital or county seats were associated with a higher probability of vaccination. The average WTP ranged from 14.2 to 30.3 EUR for the different vaccine types.

CONCLUSIONS

Males, respondents with higher education and income stated a higher WTP value for all vaccines. Better socioeconomic status increased both vaccination coverage and willingness to pay for vaccines.

COVID-19 Vaccines in the Pediatric Population: A Focus on Cardiac Patients

Due to the deleterious global impact of the COVID-19 pandemic, tremendous effort has been invested in the development of vaccines against the virus. Vaccine candidates are first tested in adult populations, a number of which have been approved for EUL by the WHO, and are in use across the USA and MENA region. The question remains whether these (or other) vaccines should be recommended to a neonatal, pediatric, and/or adolescent cohort. Incidence and severity of COVID-19 infection are low in pediatric, neonatal, and adolescent patients. Since both overall incidence and severity are lower in children than in adults, safety is an important consideration in vaccine approval for these age groups, in addition to efficacy and a decreased risk of transmission. The following review discusses vaccine immunology in children aged 0-18 years, with emphasis on the negative impact of the COVID-19 pandemic on the lives of children, considerations for pediatric vaccine approval, and available vaccines for pediatric cohorts along with a breakdown of the efficacy, advantages, and disadvantages for each. This review also contains current and future perspectives, as well as a section on the cardiovascular implications and related dynamics of pediatric COVID-19 vaccination.

Vaccine hesitancy and trust in sub-Saharan Africa

Lack of trust is a primary reason behind the global rise in vaccine hesitancy. Existing research on the trust-vaccine hesitancy nexus has almost exclusively focused on COVID-19 with the vast majority of studies examining industrialized countries. In this study, we investigated the influence of trust in different policy-relevant actors (government, science, media, pharmaceutical companies, society) on vaccine hesitancy for recently available vaccines related to polio and HPV which we benchmark against a COVID-19 vaccine. Leveraging unique primary data on 5203 individuals from six countries (Ghana, Kenya, Nigeria, South Africa, Tanzania, and Uganda), we showed that individuals' trust in the government and society are key predictors of vaccine hesitancy. Furthermore, we demonstrated that these relationships are remarkably stable across vaccine, disease, and country contexts.

Short-term side effects of BNT162b2 vaccine in primary care settings in Qatar: a retrospective study

Background

Despite the established effectiveness of the BNT162b2 Vaccine, the novel technology demands careful safety monitoring. While global studies have explored its safety, local data remains limited and exhibits some variability. This study investigated short-term side effects among BNT162b2 vaccinated individuals in Qatar.

Methods

A retrospective analysis was conducted using data extracted from the electronic health records of individuals aged 18 or older across 8 primary health centers who received either the first or second dose of the BNT162b2 vaccine during the period from December 23, 2020, to April 24, 2021. The proportions of individuals experiencing short-term side effects after each dose were calculated. Logistic regression and log binomial regression analyses were used to explore associations with the side effects.

Results

Among 7,764 participants, 5,489 received the first dose and 2,275 the second, with similar demographics between the groups. After the first dose, 5.5% reported at least one local side effect, compared to 3.9% after the second, with a 1.4 times higher incidence after the first dose (RR 1.4, 95% CI 1.14-1.75) compared to the second. Systemic side effects after the second dose were 2.6 times more common than after the first (RR 2.6, 95% CI 2.15-3.14). Gender, nationality, history of prior COVID-19 infection, and obesity were significantly associated with side effects after the first dose, while age, gender, and nationality, were significant factors after the second dose.

Conclusion

The rates of side effects following the BNT162b2 vaccine in Qatar were relatively low, with age, gender, nationality, previous infection, and obesity identified as significant predictors. These results emphasize the need for tailored vaccination strategies and contributes valuable insights for evidence-based decision-making in ongoing and future vaccination campaigns.

Going Forward: Potential Impact of Protein-Based COVID-19 Vaccination Coverage on Population Outcomes and Costs in the United States

Policymakers in the United States (US) recommend coronavirus disease 2019 (COVID-19) vaccination with a monovalent 2023-2024 vaccine formulation based on the Omicron XBB.1.5 variant. We estimated the potential US population-level health and economic impacts of increased COVID-19 vaccine coverage that might be expected with the availability of a protein-based vaccine with simpler storage requirements in addition to messenger ribonucleic acid (mRNA) vaccines. A Markov model was developed to estimate 1-year COVID-19-related costs, cases, hospitalizations, and deaths with and without the availability of a protein-based vaccine option. The model population was stratified by age and risk status. Model inputs were sourced from published literature or derived from publicly available data. Our model estimated that a five-percentage-point increase in coverage due to the availability of a protein-based vaccine option would prevent over 500,000 cases, 66,000 hospitalizations, and 3000 COVID-19-related deaths. These clinical outcomes translated to 42,000 quality-adjusted life years (QALYs) gained and an incremental cost-effectiveness ratio of USD 16,141/QALY from a third-party payer perspective. In sensitivity analyses, outcomes were most sensitive to COVID-19 incidence and severity across age groups. The availability of a protein-based vaccine option in the US could reduce hospitalizations and deaths and is predicted to be cost-effective.

Association between Gross National Income per capita and COVID-19 vaccination coverage: a global ecological study

BACKGROUND

Coronavirus 2019 (COVID-19) pandemic has claimed over six million lives and infected more than 650 million people globally. Public health agencies have deployed several strategies, including rolling out vaccination campaigns to curb the pandemic, yet a significant proportion of the global population has not received the COVID-19 vaccine. We assessed differences in COVID-19 vaccination coverage by Gross National Income (GNI) per capita of WHO members (i.e., countries, areas, and territories, n = 192) and by WHO member regions (n = 6).

METHODS

Using an ecological study design, we analyzed publicly available data from the WHO website merged with the World Bank's GNI per capita data. We included a total of 192 WHO members and six WHO regions in the analysis. We utilized negative binomial regression to assess the associations between the GNI per capita and COVID-19 vaccination coverage (cumulative number of persons fully vaccinated and/or received at least one dose of the vaccine per 100 population), and ANOVA test to assess the differences in vaccination coverage per WHO regions.

RESULTS

Low GNI per capita WHO members had significantly lower full vaccination coverage (aRR 0.30, 95% CI 0.22-0.40) compared to high GNI per capita WHO members. These members were also 66% less likely to receive at least one dose of the vaccine (aRR 0.34, 0.26-0.44) relative to high GNI per capita WHO members. Africa region had a significantly lower fully vaccination coverage (aRR 0.71, 95% CI 0.36-0.54) and received at least one dose of the COVID-19 vaccine (aRR 0.78, 95% CI 0.62-0.99) than Europe region. Conversely, the Western Pacific region had significantly higher fully vaccination coverage (aRR 1.40 95% CI 1.12-1.74) and received at least one dose of COVID-19 vaccines (aRR 1.40 95% CI 1.14-1.73) relative to European region.

CONCLUSION

WHO members with low GNI per capita and the African region reported significantly lower COVID-19 vaccination coverage than those with high GNI per capita or other regions. Efforts to strengthen and promote COVID-19 vaccination in low-income WHO countries and African region should be scaled up.

Initial behaviors and attitudes towards the COVID-19 vaccine in sarcoidosis patients: results of a self-reporting questionnaire

BACKGROUND

Individuals with self-declared sarcoidosis are at increased risk of COVID-19 related morbidity and mortality for which vaccination can be lifesaving. Despite this, vaccine hesitancy remains a large barrier to global acceptance of vaccination against COVID-19. We aimed to identify individuals with sarcoidosis who had and had not been vaccinated against COVID-19 vaccine to 1) establish a safety profile of COVID-19 vaccination in those with sarcoidosis and 2) to elucidate factors that contribute to COVID-19 vaccine hesitancy.

METHODS

A questionnaire inquiring about COVID-19 vaccination status, vaccination side effects, and willingness for future vaccination was distributed from December 2020 to May 2021 to individuals with sarcoidosis living in the US and European countries. Details regarding sarcoidosis manifestations and treatment were solicited. Vaccine attitudes were classified as pro or anti-COVID-19 vaccination for subgroup analysis.

RESULTS

At the time of questionnaire administration, 42% of respondents had already received a COVID-19 vaccination, most of whom either denied side effects or reported a local reaction only. Those off sarcoidosis therapy were more likely to report systemic side effects. Among subjects who had not yet received a COVID-19 vaccine, 27% of individuals reported they would not receive one once available. Reasons against vaccination were overwhelmingly related to the lack of confidence in vaccine safety and/or efficacy and less related to concerns associated with convenience or complacency. Black individuals, women, and younger adults were more likely to decline vaccination.

CONCLUSIONS

Among individuals with sarcoidosis, COVID-19 vaccination is well-accepted and well-tolerated. Subjects on sarcoidosis therapy reported significantly less vaccination side effects, and thus the correlation between side effects, vaccine type, and vaccine efficacy requires further investigation. Strategies to improve vaccination should focus on improving knowledge and education regarding vaccine safety and efficacy, as well as targeting sources of misinformation, particularly in young, black, and female subpopulations.

Say it right: measuring the impact of different communication strategies on the decision to get vaccinated

BACKGROUND

Vaccine hesitancy is a concerning menace to the control of vaccine-preventable diseases. Effective health communication could promote an overall understanding of the importance, risks, and benefits of vaccination and reduce vaccine hesitancy.

METHODS

In this survey, four fictitious newspaper articles addressing an emerging bogus disease and its vaccine were randomly assigned to participants. The first version focused on information about the disease; the second was akin to the first, including a case description and image. The third version focused on vaccine safety/efficacy; the fourth version was like the third, including a case description and image. After reading a single version of the article, participants responded if they would take the vaccine and if they would vaccinate their children. We used chi-squared tests for comparisons and investigated interactions with vaccine-hesitant attitudes.

RESULTS

We included 5233 participants between August/2021 and January/2022; 790 were caregivers of a child ≤ 5 years old, and 15% had prior vaccine hesitancy. Although most declared intention to take the vaccine, the percentage was highest among those exposed to the newspaper article focusing on the vaccine safety/efficacy with the case description and picture (91%; 95% confidence interval 89-92%), and lowest among participants exposed to the article focusing on the disease with no case description (84%; 95% confidence interval 82-86%). Similar trends were observed in the intention of offspring vaccination. We found evidence of effect modification by vaccine-hesitant attitudes, with a higher impact of communication focusing on vaccine safety/efficacy compared to that focusing on disease characteristics among hesitant participants.

CONCLUSION

Communication strategies focusing on different aspects of the disease-vaccine duet may impact vaccine hesitancy, and storytelling/emotive imagery descriptions may improve risk perception and vaccine uptake. Moreover, the effect of message framing strategies may differ according to previous vaccine hesitant attitudes.

Online listing data and their interaction with market dynamics: evidence from Singapore during COVID-19

With the emergence of Property Technology, online listing data have drawn increasing interest in the field of real estate-related big data research. Scraped from the online platforms for property search and marketing, these data reflect real-time information on housing supply and potential demand before actual transaction data are released. This paper analyzes the interactions between the keywords of online home listings and actual market dynamics. To do so, we link the listing data from the major online platform in Singapore with the universal transaction data of resale public housing. We consider the COVID-19 outbreak as a natural shock that brought a significant change to work modes and mobility and, in turn, consumer preference changes for home purchases. Using the Difference-in-Difference approach, we first find that housing units with a higher floor level and more rooms have experienced a significant increase in transaction prices while close proximity to public transportation and the central business district (CBD) led to a reduction in the price premium after COVID-19. Our text analysis results, using the natural language processing, suggest that the online listing keywords have consistently captured these trends and provide qualitative insights (e.g. view becoming increasingly popular) that could not be uncovered from the conventional database. Relevant keywords reveal trends earlier than transaction-based data, or at least in a timely manner. We demonstrate that big data analytics could effectively be applied to emerging social science research such as online listing research and provide useful information to forecast future market trends and household demand.

The political component of COVID-19 vaccine choice: Results from a conjoint experiment

OBJECTIVES

Prior research highlights the role of efficacy, vaccine safety, and availability in vaccine hesitancy. Research is needed to better understand the political driving forces behind COVID-19 vaccine uptake. We examine the effects of the origin of a vaccine, and approval status within the EU on vaccine choice. We also test if these effects differ by party affiliation among Hungarians.

STUDY DESIGN

We use a conjoint experimental design to assess multiple causal relationships. Respondents choose between two hypothetical vaccine profiles randomly generated from 10 attributes. The data were gathered from an online panel in September 2022. We applied a quota for vaccination status and party preference. Three hundred twenty-four respondents evaluated 3888 randomly generated vaccine profiles.

METHODS

We analyse the data using an OLS estimator with standard errors clustered by respondents. To further nuance our results, we test for task, profile, and treatment heterogeneity effects.

RESULTS

By origin, respondents prefer German (MM 0.55; 95% CI 0.52-0.58) and Hungarian (0.55; 0.52-0.59) vaccines over US (0.49; 0.45-0.52) and Chinese vaccines (0.44; 0.41-0.47). By approval status, vaccines approved by the EU (0.55, 0.52-0.57) or pending authorization (0.5, 0.48-0.53) are preferred over unauthorised ones (0.45, 0.43-0.47). Both effects are conditional on party affiliation. Government voters especially prefer Hungarian vaccines (0.6; 0.55-0.65) over others.

CONCLUSIONS

The complexity of vaccination decisions calls for the usage of information shortcuts. Our findings demonstrate a strong political component that motivates vaccine choice. We demonstrate that politics and ideology have broken into fields of individual-level decisions such as health.

Coverage of primary and booster vaccination against COVID-19 by socioeconomic level: A nationwide cross-sectional registry study

High and equitable COVID-19 vaccination coverage is important for pandemic control and prevention of health inequity. However, little is known about socioeconomic correlates of booster vaccination coverage. In this cross-sectional study of all Norwegian adults in the national vaccination program (N = 4,190,655), we use individual-level registry data to examine coverage by levels of household income and education of primary (≥2 doses) and booster (≥3 doses) vaccination against COVID-19. We stratify the analyses by age groups with different booster recommendations and report relative risk ratios (RR) for vaccination by 25 August 2022. In the 18-44 y group, individuals with highest vs. lowest education had 94% vs. 79% primary coverage (adjusted RR (adjRR) 1.15, 95%CI 1.14-1.15) and 67% vs. 38% booster coverage (adjRR 1.55, 95% CI 1.55-1.56), while individuals with highest vs. lowest income had 94% vs. 81% primary coverage (adjRR 1.10, 95%CI 1.10-1.10) and 60% vs. 43% booster coverage (adjRR 1.23, 95%CI 1.22-1.24). In the ≥45 y group, individuals with highest vs. lowest education had 96% vs. 92% primary coverage (adjRR 1.02, 95%CI 1.02-1.02) and 88% vs. 80% booster coverage (adjRR 1.09, 95%CI 1.09-1.09), while individuals with highest vs. lowest income had 98% vs. 82% primary coverage (adjRR 1.16, 95%CI 1.16-1.16) and 92% vs. 64% booster coverage (adjRR 1.33, 95%CI 1.33-1.34). In conclusion, we document large socioeconomic inequalities in COVID-19 vaccination coverage, especially for booster vaccination, even though all vaccination was free-of-charge. The results highlight the need to tailor information and to target underserved groups for booster vaccination.

Examination of Preferences for COVID-19 Vaccines in Hungary Based on Their Properties-Examining the Impact of Pandemic Awareness with a Hybrid Choice Approach

The COVID-19 pandemic has posed a huge challenge to the world in recent years. The development of vaccines that are as effective as possible and accessible to society offers a promising alternative for addressing the problems caused by this situation as soon as possible and to restore the pre-epidemic system. The present study investigated the preferences of residents in Hungary's second-largest city (Debrecen) for the COVID-19 vaccine. To achieve this aim, a discrete choice experiment was conducted with 1011 participants, and the vaccine characteristics included in the design of the experiment were determined by qualitative methods and a pilot survey: (1) country of origin; (2) efficiency; (3) side effect; and (4) duration of protection. During the data collection at three vaccination sites, respondents were asked to choose between three vaccine alternatives and one "no choice" option in eight decision situations. Discrete choice model estimations were performed using a random parameter logit (RPL) specification with the final model extended to include a latent variable measuring pandemic awareness. The results showed that the vaccine with a Chinese country of origin is the least preferred among the respondents, while the Hungarian and the European vaccines are the most preferred. Furthermore, the increase in the vaccine efficiency level increased the respondents' sense of utility for the vaccine; the short-term side effect was preferred to the long-term one; and the increase in the duration of protection provided by the vaccine increased the respondents' sense of utility for the vaccine. Based on the parameter estimated for the latent variable, it can be concluded that as the level of pandemic awareness (which is more positive among people with chronic diseases and less important among health workers) increases, the choice of a vaccine option becomes more preferred among respondents compared to the "no choice". The results of our investigation could contribute towards increasing compliance in the case of the vaccination-rejecting population, not only for COVID-19, but for any kind of vaccination procedure.

Changes in Attitudes toward COVID-19 Vaccination and Vaccine Uptake during Pandemic

The epidemic control approach was based on non-pharmacological measures in the first year of the COVID-19 pandemic, followed by vaccine uptake in the second year. Vaccine uptake depends on the individual attitude toward vaccination. The aim was to assess the changes in attitudes regarding COVID-19 vaccine protection during the pandemic and to determine the vaccination uptake concerning these attitudes. A panel study on COVID-19 vaccine attitudes and vaccination against COVID-19 was conducted in Belgrade, Serbia. The first survey was carried out in May−June 2020, and the second survey was organized in August−September 2021. During the baseline testing performed in 2020, 64.4% of respondents believed that the future vaccine against COVID-19 could protect against the COVID-19 disease, while 9.7% thought that it could not, and 25.9% were unsure. One year later, in the second survey, the percentage of participants with positive attitudes was slightly lower (64.7% vs. 62.5%). However, negative attitudes turned positive in 34% of cases, and 28.9% became unsure about vaccine protection (p < 0.001). Out of the 390 participants included in the study, 79.7% were vaccinated against COVID-19 until follow-up. There is a statistically significant difference in vaccination uptake compared to the baseline attitude about the protection of the COVID-19 vaccine. The main finding of our study is that the majority of participants who were vaccine hesitant during the baseline testing changed their opinion during the follow-up period. Additionally, the baseline attitude about the protection of the COVID-19 vaccine has been shown to be a potential determinant of vaccination uptake.

Estimated global public health and economic impact of COVID-19 vaccines in the pre-omicron era using real-world empirical data

BACKGROUND

Limited data are available describing the global impact of COVID-19 vaccines. This study estimated the global public health and economic impact of COVID-19 vaccines before the emergence of the Omicron variant.

METHODS

A static model covering 215 countries/territories compared the direct effects of COVID-19 vaccination to no vaccination during 13 December 2020-30 September 2021. After adjusting for underreporting of cases and deaths, base case analyses estimated total cases and deaths averted, and direct outpatient and productivity costs saved through averted health outcomes. Sensitivity analyses applied alternative model assumptions.

RESULTS

COVID-19 vaccines prevented an estimated median (IQR) of 151.7 (133.7-226.1) million cases and 620.5 (411.1-698.1) thousand deaths globally through September 2021. In sensitivity analysis applying an alternative underreporting assumption, median deaths averted were 2.1 million. Estimated direct outpatient cost savings were $21.2 ($18.9-30.9) billion and indirect savings of avoided productivity loss were $135.1 ($121.1-206.4) billion, yielding a total cost savings of $155 billion globally through averted infections.

CONCLUSIONS

Using a conservative modeling approach that considered direct effects only, we estimated that COVID-19 vaccines have averted millions of infections and deaths, generating billions of cost savings worldwide, which underscore the continued importance of vaccination in public health response to COVID-19.