HighlightsWHO vaccine hesitancy definition understood; >90% countries report hesitancy.Long list of reasons, varied by country income level; WHO region, changed overtime.Most cited: risk-benefit (scientific evidence) equaled <25% of reasons cited.Reasons cited based on assessments in only 1/3 of countries; need to increase this.

CONTEXT: Several varicella vaccines are available worldwide. Countries with a varicella vaccination program use 1-or 2-dose schedules. OBJECTIVE:We examined postlicensure estimates of varicella vaccine effectiveness (VE) among healthy children.DATA SOURCES: Systematic review and descriptive and meta-analysis of Medline, Embase, Cochrane libraries, and CINAHL databases for reports published during 1995-2014. STUDY SELECTION:Publications that reported original data on dose-specific varicella VE among immunocompetent children. DATA EXTRACTION:We used random effects meta-analysis models to obtain pooled one dose VE estimates by disease severity (all varicella and moderate/severe varicella). Within each severity category, we assessed pooled VE by vaccine and by study design. We used descriptive statistics to summarize 1-dose VE against severe disease. For 2-dose VE, we calculated pooled estimates against all varicella and by study design. RESULTS:The pooled 1-dose VE was 81% (95% confidence interval [CI]: 78%-84%) against all varicella and 98% (95% CI: 97%-99%) against moderate/severe varicella with no significant association between VE and vaccine type or study design (P > .1). For 1 dose, median VE for prevention of severe disease was 100% (mean = 99.4%). The pooled 2-dose VE against all varicella was 92% (95% CI: 88%-95%), with similar estimates by study design.LIMITATIONS: VE was assessed primarily during outbreak investigations and using clinically diagnosed varicella. CONCLUSIONS:One dose of varicella vaccine was moderately effective in preventing all varicella and highly effective in preventing moderate/severe varicella, with no differences by vaccine. The second dose adds improved protection against all varicella.a National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and b Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland Dr Marin conceptualized and designed the study, reviewed the articles and collected the data, supervised the analysis, interpreted the data, drafted the initial manuscript, and revised the manuscript; Dr Marti conceptualized the study, reviewed part of the articles, interpreted the data, and reviewed and revised the manuscript; Ms Kambhampati carried out the meta-analyses, interpreted the data, and reviewed the manuscript; Dr Jeram conducted an initial literature review, reviewed part of the articles and collected the data, and reviewed the manuscript; Dr Seward conceptualized and designed the study, reviewed part of the articles, critically reviewed the manuscript, and interpreted the data; and all authors approved the fi nal manuscript as submitted.The fi ndings and conclusions in this report are those of the authors and do not necessarily represent the offi cial position of the Centers for Disease Control and Prevention. For authors affi liated with the World Health Organization, the authors alone are responsible for the views expressed in this publication ...

Background Different forms of vaccines have been developed to prevent the SARS‐CoV‐2 virus and subsequent COVID‐19 disease. Several are in widespread use globally. Objectives To assess the efficacy and safety of COVID‐19 vaccines (as a full primary vaccination series or a booster dose) against SARS‐CoV‐2. Search methods We searched the Cochrane COVID‐19 Study Register and the COVID‐19 L·OVE platform (last search date 5 November 2021). We also searched the WHO International Clinical Trials Registry Platform, regulatory agency websites, and Retraction Watch. Selection criteria We included randomized controlled trials (RCTs) comparing COVID‐19 vaccines to placebo, no vaccine, other active vaccines, or other vaccine schedules. Data collection and analysis We used standard Cochrane methods. We used GRADE to assess the certainty of evidence for all except immunogenicity outcomes. We synthesized data for each vaccine separately and presented summary effect estimates with 95% confidence intervals (CIs). Main results We included and analyzed 41 RCTs assessing 12 different vaccines, including homologous and heterologous vaccine schedules and the effect of booster doses. Thirty‐two RCTs were multicentre and five were multinational. The sample sizes of RCTs were 60 to 44,325 participants. Participants were aged: 18 years or older in 36 RCTs; 12 years or older in one RCT; 12 to 17 years in two RCTs; and three to 17 years in two RCTs. Twenty‐nine RCTs provided results for individuals aged over 60 years, and three RCTs included immunocompromized patients. No trials included pregnant women. Sixteen RCTs had two‐month follow‐up or less, 20 RCTs had two to six months, and five RCTs had greater than six to 12 months or less. Eighteen reports were based on preplanned interim analyses. Overall risk of bias was low for all outcomes in eight RCTs, while 33 had concerns for at least one outcome. We identified 343 registered RCTs with results not yet available. This abstract reports results for the critical outcomes of confirmed symptomatic COVID‐19, severe and critical COVID‐19, and serious adverse events only for the 10 WHO‐approved vaccines. For remaining outcomes and vaccines, see main text. The evidence for mortality was generally sparse and of low or very low certainty for all WHO‐approved vaccines, except AD26.COV2.S (Janssen), which probably reduces the risk of all‐cause mortality (risk ratio (RR) 0.25, 95% CI 0.09 to 0.67; 1 RCT, 43,783 participants; high‐certainty evidence). Confirmed symptomatic COVID‐19 High‐certainty evidence found that BNT162b2 (BioNtech/Fosun Pharma/Pfizer), mRNA‐1273 (ModernaTx), ChAdOx1 (Oxford/AstraZeneca), Ad26.COV2.S, BBIBP‐CorV (Sinopharm‐Beijing), and BBV152 (Bharat Biotect) reduce the incidence of symptomatic COVI...

Vaccine hesitancy has become the focus of growing attention and concern globally despite overwhelming evidence of the value of vaccines in preventing disease and saving the lives of millions of individuals every year.Measuring vaccine hesitancy and its determinants worldwide is important in order to understand the scope of the problem and for the development of evidence-based targeted strategies to reduce hesitancy.Two indicators to assess vaccine hesitancy were developed to capture its nature and scope at the national and subnational level to collect data in 2014: 1) The top 3 reasons for not accepting vaccines according to the national schedule in the past year and whether the response was opinion- or assessment-based and 2) Whether an assessment (or measurement) of the level of confidence in vaccination had taken place at national or subnational level in the previous 5 years.The most frequently cited reasons for vaccine hesitancy globally related to (1) the risk-benefit of vaccines, (2) knowledge and awareness issues, (3) religious, cultural, gender or socio-economic factors. Major issues were fear of side effects, distrust in vaccination and lack of information on immunization or immunization services. The analysis revealed that 29% of all countries had done an assessment of the level of confidence in their country, suggesting that vaccine confidence was an issue of importance.Monitoring vaccine hesitancy is critical because of its influence on the success of immunization programs. To our knowledge, the proposed indicators provide the first global snapshot of reasons driving vaccine hesitancy and depicting its widespread nature, as well as the extent of assessments conducted by countries.

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