COVID-19 vaccine uptake,effectiveness, and waning in 82,959 health care workers: A national prospective cohort study in Wales

BackgroundWhile population estimates suggest high vaccine effectiveness against SARS-CoV-2 infection, the protection for health care workers, who are at higher risk of SARS-CoV-2 exposure, is less understood.MethodsWe conducted a national cohort study of health care workers in Wales (UK) from 7 December 2020 to 30 September 2021. We examined uptake of any COVID-19 vaccine, and the effectiveness of BNT162b2 mRNA (Pfizer-BioNTech) against polymerase chain reaction (PCR) confirmed SARS-CoV-2 infection. We used linked and routinely collected national-scale data within the SAIL Databank. Data were available on 82,959 health care workers in Wales, with exposure extending to 26 weeks after second doses.ResultsOverall vaccine uptake was high (90%), with most health care workers receiving the BNT162b2 vaccine (79%). Vaccine uptake differed by age, staff role, socioeconomic status; those aged 50–59 and 60+ years old were 1.6 times more likely to get vaccinated than those aged 16–29. Medical and dental staff, and Allied Health Practitioners were 1.5 and 1.1 times more likely to get vaccinated, compared to nursing and midwifery staff. The effectiveness of the BNT162b2 vaccine was found to be strong and consistent across the characteristics considered; 52% three to six weeks after first dose, 86% from two weeks after second dose, though this declined to 53% from 22 weeks after the second dose.ConclusionsWith some variation in rate of uptake, those who were vaccinated had a reduced risk of PCR-confirmed SARS-CoV-2 infection, compared to those unvaccinated. Second dose has provided stronger protection for longer than first dose but our study is consistent with waning from seven weeks onwards.     

COVID-19 booster vaccination uptake and infection breakthrough amongst health care workers in Wales: A national prospective cohort study

BackgroundFrom September 2021, Health Care Workers (HCWs) in Wales began receiving a COVID-19 booster vaccination. This is the first dose beyond the primary vaccination schedule. Given the emergence of new variants, vaccine waning vaccine, and increasing vaccination hesitancy, there is a need to understand booster vaccine uptake and subsequent breakthrough in this high-risk population.MethodsWe conducted a prospective, national-scale, observational cohort study of HCWs in Wales using anonymised, linked data from the SAIL Databank. We analysed uptake of COVID-19 booster vaccinations from September 2021 to February 2022, with comparisons against uptake of the initial primary vaccination schedule. We also analysed booster breakthrough, in the form of PCR-confirmed SARS-Cov-2 infection, comparing to the second primary dose. Cox proportional hazard models were used to estimate associations for vaccination uptake and breakthrough regarding staff roles, socio-demographics, household composition, and other factors.ResultsWe derived a cohort of 73,030 HCWs living in Wales (78% female, 60% 18–49 years old). Uptake was quickest amongst HCWs aged 60 + years old (aHR 2.54, 95%CI 2.45–2.63), compared with those aged 18–29. Asian HCWs had quicker uptake (aHR 1.18, 95%CI 1.14–1.22), whilst Black HCWs had slower uptake (aHR 0.67, 95%CI 0.61–0.74), compared to white HCWs. HCWs residing in the least deprived areas were slightly quicker to have received a booster dose (aHR 1.12, 95%CI 1.09–1.16), compared with those in the most deprived areas. Strongest associations with breakthrough infections were found for those living with children (aHR 1.52, 95%CI 1.41–1.63), compared to two-adult only households. HCWs aged 60 + years old were less likely to get breakthrough infections, compared to those aged 18–29 (aHR 0.42, 95%CI 0.38–0.47).ConclusionVaccination uptake was consistently lower among black HCWs, as well as those from deprived areas. Whilst breakthrough infections were highest in households with children.     

Perceptions of the COVID-19 vaccine and willingness to receive vaccination among health workers in Nigeria

ObjectivesThe study aimed to examine health workers’ perceptions of the coronavirus disease 2019 vaccine in Nigeria and their willingness to receive the vaccine when it becomes available.Methods This multi-center cross-sectional study used non-probability convenience sampling to enroll 1,470 hospital workers aged 18 and above from 4 specialized hospitals. A structured and validated self-administered questionnaire was used for data collection. Data entry and analysis were conducted using IBM SPSS ver. 22.0.Results The mean age of respondents was 40±6 years. Only 53.5% of the health workers had positive perceptions of the COVID-19 vaccine, and only slightly more than half (55.5%) were willing to receive vaccination. Predictors of willingness to receive the COVID-19 vaccine included having a positive perception of the vaccine (adjusted odds ratio [AOR], 4.55; 95% confidence interval [CI], 3.50−5.69), perceiving a risk of contracting COVID-19 (AOR, 1.50; 95% CI, 1.25–3.98), having received tertiary education (AOR, 3.50; 95% CI, 1.40−6.86), and being a clinical health worker (AOR, 1.25; 95% CI, 1.01−1.68).Conclusion Perceptions of the COVID-19 vaccine and willingness to receive the vaccine were sub-optimal among this group. Educational interventions to improve health workers'' perceptions and attitudes toward the COVID-19 vaccine are needed.     

Respiratory protection for health care workers: A 2020 COVID-19 perspective

As the US health care system began to respond to the coronavirus disease-2019 pandemic, demand for respiratory personal protective equipment (PPE) increased precipitously, as did the number of users. This commentary discusses ensuing deviations from accepted respiratory PPE program practices, which potentially increased risk to health care workers. Such lapses included omitting user training and fit testing, provision of unapproved devices, and application of devices in settings and ways for which they were not intended. The temporary compromise of professionally accepted standards due to exigencies must not become the new normal. Rather, the current attention to PPE should be leveraged to enhance practice, motivate vital research, and strengthen professional, governmental, and institutional capabilities to control health care worker exposures to infectious hazards.     

Exploring vaccination coverage and attitudes of health care workers towards influenza vaccine in Cyprus

Seasonal influenza is a major public health problem. Nosocomial influenza is particularly concerning as it may affect patients at high risk for complications. Unvaccinated health care workers (HCWs) are an important source of nosocomial influenza and therefore a priority target group for vaccination. Despite the fact that some European countries have high coverage rates such as UK (76.8% in season 2020/21), others continue to have low coverage rates for influenza vaccines. This study aims to estimate vaccination coverage in HCWs in Cyprus, an island country located in the Eastern Mediterranean region and describe their attitudes towards influenza vaccination.MethodsThis is a questionnaire based, nation-wide study assessing flu vaccination coverage in 2019–2020 and attitudes related to vaccination acceptance, of 962 HCWs in both public and private health care facilities. Multivariable logistic regression was used to investigate factors associated with flu vaccination status.ResultsFlu vaccination coverage was estimated as 31.8%. The top two reasons for getting vaccinated were to protect their family (81.4%) and themselves (77.4%). The top two reasons for not getting immunised, besides “no particular reason” (25.7%), included disbelief for vaccine effectiveness (21.5%) and safety (29.3%). The regression model showed that doctors compared to nurses had 10 times the odds of being vaccinated. Other factors positively associated with flu vaccination were encouragement by the supervisor, having sufficient knowledge on flu and flu vaccination and easy access to vaccination. A percentage of 54.8% of participants stated that COVID-19 pandemic strongly or somewhat influenced their decision to get vaccinated.ConclusionFlu vaccination coverage in HCWs in Cyprus is rather low, similar to some other European countries. Barriers and facilitators in this study can be considered in strategies to increase flu vaccination uptake. Such questionnaire-based surveys should be repeated in order to evaluate effectiveness of targeted vaccination campaigns.     

Employer requirements and COVID-19 vaccination and attitudes among healthcare personnel in the U.S.: Findings from National Immunization Survey Adult COVID Module,August – September 2021

IntroductionEmployer vaccination requirements have been used to increase vaccination uptake among healthcare personnel (HCP). In summer 2021, HCP were the group most likely to have employer requirements for COVID-19 vaccinations as healthcare facilities led the implementation of such requirements. This study examined the association between employer requirements and HCP’s COVID-19 vaccination status and attitudes about the vaccine.MethodsParticipants were a national representative sample of United States (US) adults who completed the National Immunization Survey Adult COVID Module (NIS-ACM) during August–September 2021. Respondents were asked about COVID-19 vaccination and intent, requirements for vaccination, place of work, attitudes surrounding vaccinations, and sociodemographic variables. This analysis focused on HCP respondents. We first calculated the weighted proportion reporting COVID-19 vaccination for HCP by sociodemographic variables. Then we computed unadjusted and adjusted prevalence ratios for vaccination coverage and key indicators on vaccine attitudes, comparing HCP based on individual self-report of vaccination requirements.ResultsOf 12,875 HCP respondents, 41.5% reported COVID-19 vaccination employer requirements. Among HCP with vaccination requirements, 90.5% had been vaccinated against COVID-19, as compared to 73.3% of HCP without vaccination requirements—a pattern consistent across sociodemographic groups. Notably, the greatest differences in uptake between HCP with and without employee requirements were seen in sociodemographic subgroups with the lowest vaccination uptake, e.g., HCP aged 18–29 years, HCP with high school or less education, HCP living below poverty, and uninsured HCP. In every sociodemographic subgroup examined, vaccine uptake was more equitable among HCP with vaccination requirements than in HCP without. Finally, HCP with vaccination requirements were also more likely to express confidence in the vaccine’s safety (68.3% vs. 60.1%) and importance (89.6% vs 79.6%).ConclusionIn a large national US sample, employer requirements were associated with higher and more equitable HCP vaccination uptake across all sociodemographic groups examined. Our findings suggest that employer requirements can contribute to improving COVID-19 vaccination coverage, similar to patterns seen for other vaccines.     

Assessing the effectiveness of zoster vaccine live: A retrospective cohort study using primary care data in the United Kingdom

BackgroundHerpes zoster (shingles) is a common viral disease increasing in risk and severity with age. Post-herpetic neuralgia (PHN), a complication of shingles, causes severe pain impacting quality of life (QoL). Zoster Vaccine Live (ZVL), a licensed vaccine for the prevention of shingles in the United Kingdom (UK), is part of the national immunisation programme (NIP) for adults aged 70–79. Public Health England (PHE) reports show shingles vaccine coverage varies, but is typically 50–60% across eligible cohorts.Materials/methodsThis retrospective, matched cohort study was conducted using The Health Improvement Network (THIN) UK primary care database. Individuals aged 70–79 were classified based on their vaccination status between September 2013 and May 2016. Risk and incidence rates for shingles were calculated for both groups over the duration of the study (mean 1.2 years). Vaccine effectiveness (VE) was calculated using the equation 1-relative risk (RR) for shingles and PHN.ResultsWithin the total cohort (n = 295,135), 70,867 (24%) were vaccinated and 224,268 (76%) were unvaccinated. 2435 (0.83%) patients developed shingles: 241 (0.34%) among the vaccinated and 2194 (0.98%) among the unvaccinated. The VE for preventing shingles was 65.3% (95% CI: 60.3–69.6%). The incidence rate in the vaccinated group was 2.95 (95% CI: 2.59–3.34) vs 8.02 (95% CI: 7.68–8.36) per 1000 person years in the unvaccinated group. Risk of PHN was 0.02% and 0.06% in the respective vaccinated and unvaccinated groups. The VE for preventing PHN was 72% (95% CI: 50.0–83.9%). PHN incidence rates were 0.16 (95% CI: 0.08–0.27) and 0.53 (95% CI: 0.44–0.62) per 1000 person years in the vaccinated and unvaccinated groups, respectively.ConclusionsZVL reduced the risk of shingles among an elderly population. Given the negative impact of shingles and PHN on QoL, the benefits of vaccination are clear. Improving uptake in the UK is needed in this population.     

Predictors of vaccine hesitancy among disability support workers in Australia: A cross-sectional survey

BackgroundAchieving high levels of vaccination among disability support workers (DSWs) is critical to protecting people with disability from COVID-19 and other vaccine-preventable diseases.ObjectiveTo identify how demographic factors, risk perceptions of COVID-19 and the COVID-19 vaccine, and views about COVID-19 vaccination are associated with COVID-19 vaccine hesitancy among DSWs.MethodsSurvey of 252 Australian DSWs conducted in March and early April 2021. Participants were classified as vaccine hesitant if they had not been vaccinated and would not have the vaccine when offered it. Logistic regression analysis was used to control for confounders.Results52.4% of DSWs were hesitant with females being more likely to be hesitant than males (58.2% female, 38.1% male). Hesitancy was more frequent among DSWs who were not worried about COVID-19 for themselves or their family (adjusted odds ratio (AOR) 1.86, 95% CI 1.0–3.45); did not agree they were at more risk than the rest of the community (AOR 2.29, 95% 1.25–4.20); were concerned about vaccine safety (AOR 22.86, 95% CI 10.59–49.13) and were not confident the vaccine would protect them (AOR 6.06, 95% CI 3.21–11.41) or the clients from COVID-19 (AOR 6.03, 95% CI 3.19–11.41). DSWs who thought vaccination was a personal choice were more likely to be hesitant (82.1%) than those who thought it was a community responsibility (27.6%).ConclusionsThe study shows that increasing vaccination rates among DSWs requires targeted strategies that emphasise the seriousness of the infection; the potential for vaccines to reduce transmission; and vaccine safety and efficacy.     

COVID-19 clinical outcomes by patient disability status: A retrospective cohort study

BackgroundPeople with disabilities might experience worse clinical outcomes of SARS-CoV-2 infection, but evidence is limited.ObjectiveTo investigate if people with disabilities requiring assistance are more likely to experience severe COVID-19 or death.MethodsData from the Johns Hopkins COVID-19 Precision Medicine Analytics Platform Registry (JH-CROWN) included 6494 adult patients diagnosed with COVID-19 and admitted between March 4, 2020–October 29, 2021. Severe COVID-19 and death were defined using the occurrence and timing of clinical events. Assistive needs due to disabilities were reported by patients or their proxies upon admission. Multivariable-adjusted Cox proportional hazards models were used to examine the associations between disability status and severe COVID-19 or death. Primary models adjusted for demographics and secondary models additionally adjusted for clinical covariates.ResultsIn this clinical cohort (47–73 years, 49% female, 39% Black), patients with disabilities requiring assistance had 1.35 times (95% confidence interval [CI]:1.01, 1.81) the hazard of severe COVID-19 among patients <65 years, but not among those ≥65 years, equating to an additional 17.5 severe COVID-19 cases (95% CI:7.7, 28.2) per 100 patients. A lower risk of mortality was found among patients <65 years, but this finding was not robust due to the small number of deaths.ConclusionsPeople with disabilities requiring assistance aged <65 years are more likely to develop severe COVID-19. Although our study is limited by using a medical model of disability, these analyses intend to further our understanding of COVID-19 outcomes among people with disabilities. Also, standardized disability data collection within electronic health records is needed.     

流感灭活疫苗在中国应用效果的Meta分析

目的 了解流感疫苗免疫效果.方法 对国内1998年3月至2008年5月公开发表的符合入选标准的有关流感疫苗免疫效果的研究文献,根据各研究结果的同质性,利用随机效应模型或固定效应模型进行Meta分析.结果 初筛选出16篇文献,有13篇文献符合入选标准,11篇为队列研究,2篇为随机对照研究.对队列研究进行Meta分析发现流感疫苗预防流感样疾病效果,儿童为66%(51%～76%),成年人47%(25%～63%),老年人53%(20%～72%).结论 流感疫苗可有效预防各年龄段流感样疾病的发生.     

The impact of the COVID-19 pandemic on vaccine coverage in Kilifi,Kenya: A retrospective cohort study

The COVID-19 pandemic caused unprecedented disruption in health service delivery, globally. This study sought to provide evidence on the impact of the pandemic on vaccine coverage in Kilifi County, Kenya. We conducted a vaccine coverage survey between April and June 2021 within the Kilifi Health and Demographic Surveillance System (KHDSS). Simple random sampling was used to identify 1500 children aged 6 weeks–59 months. Participants were grouped into three retrospective cohorts based on when they became age-eligible for vaccination: before the pandemic, during the first year, or during the second year of the pandemic. Survival analysis with Cox regression was used to evaluate the association between the time-period at which participants became age-eligible for vaccination and the rate of vaccination within a month of age-eligibility for the third dose of pentavalent vaccine (Pentavalent-3) and within three months of age-eligibility for the first dose of Measles vaccine (MCV-1). A total of 1,341 participants were included in the survey. Compared to the pre-COVID-19 baseline period, the rate of vaccination within a month of age-eligibility for Pentavalent-3 was not significantly different in the first year of the pandemic (adjusted hazard ratio [aHR] 1.03, 95 % confidence interval [CI] 0.90–1.18) and was significantly higher during the second year of the pandemic (aHR 1.33, 95 % CI 1.07–1.65). The rate of vaccination with MCV-1 within three months of age-eligibility was not significantly different among those age-eligible for vaccination during the first year of the pandemic (aHR 1.04, 95 % CI 0.88–1.21) and was 35 % higher during the second year of the pandemic (95 % CI 1.11–1.64), compared to those age-eligible pre-COVID-19. After adjusting for known determinants of vaccination, the COVID-19 pandemic did not adversely affect the rate of vaccination within the KHDSS.     

Perspectives on the receipt of a COVID-19 vaccine: A survey of employees in two large hospitals in Philadelphia

BackgroundHealth care personnel have been identified by the ACIP as a priority group for COVID-19 vaccination. We conducted a survey in November-December 2020 at two large, academic hospitals in Philadelphia to evaluate the intention of hospital employees to be vaccinated.MethodsThe survey was sent electronically to all employees (clinical and nonclinical staff) at a children’s hospital and an adult hospital. The survey was voluntary and confidential. Questions focused on plans to receive a COVID-19 vaccine when available, reasons why employees would/would not get vaccinated, when employees planned to be vaccinated, vaccine safety and efficacy features that would be acceptable, and past history of receipt of other vaccines by the employee and family. Responses were analyzed using univariate and multiple logistic regression methods.ResultsA total of 12,034 hospital employees completed the survey (a 34.5% response rate). Overall, 63.7% of employees reported that they planned to receive a COVID-19 vaccine, 26.3% were unsure, and 10.0% did not plan to be vaccinated. Over 80% of those unsure or unwilling to be vaccinated expressed concerns about vaccine side effects and the vaccines’ newness. In multivariable logistic regression, persons planning to take a COVID-19 vaccine were more likely to be older, male, more educated, Asian or White, up-to-date on vaccinations, without direct patient contact, and tested for COVID-19 in the past. No significant difference in intention to be vaccinated was found between those with higher versus lower levels of exposure to COVID-19 patients or the number of previous exposures to patients with COVID-19.ConclusionsWhile the majority of hospital employees are planning to receive a COVID-19 vaccine, many are unsure or not planning to do so. Further education of hospital employees about the safety, efficacy, and value of the currently available COVID-19 vaccines is critical to vaccine acceptance in this population.     

Cohort study of Covid-19 vaccine effectiveness among healthcare workers in Finland,December 2020 - October 2021

Recently, Covid-19 vaccine effectiveness has decreased especially against mild disease due to emergence of the Delta variant and waning protection. In this register-based study among healthcare workers in Finland, the vaccine effectiveness of two-dose mRNA vaccine series against SARS-CoV-2 infection decreased from 82% (95% CI 79–85%) 14–90 days after vaccination to 53% (43–62%) after 6 months. Similar trend was observed for other series. Waning was not observed against Covid-19 hospitalization. These results facilitate decision-making of booster doses for healthcare workers.     

COVID-19 outbreak in an elderly care home: Very low vaccine effectiveness and late impact of booster vaccination campaign

BackgroundElderly people in long-term care facilities (LTCF) are at higher risk for (severe) COVID-19, yet evidence of vaccine effectiveness (VE) in this population is scarce. In November 2021 (Delta period), a COVID-19 outbreak occurred at a LTCF in the Netherlands, continuing despite measures and booster vaccination campaign. We investigated the outbreak to assess VE of primary COVID-19 vaccination against SARS-CoV-2 infection and mortality, and to describe the impact of the booster vaccination.MethodsWe calculated attack rate (AR) and case fatality (CF) per vaccination status (unvaccinated, primarily vaccinated and boostered). We calculated VE – at on average 6 months after vaccination – as 1- risk ratio (RR) using the crude risk ratio (RR) with 95% confidence intervals (CI) for the association between vaccination status (primary vaccination versus unvaccinated) and outcomes (SARS-CoV-2 infection and mortality < 30 days after testing positive for SARS-CoV-2).ResultsThe overall AR was 67% (70/105). CF was 33% (2/6) among unvaccinated cases, 12% among primarily vaccinated (7/58) and 0% (0/5) among boostered. The VE of primary vaccination was 17% (95% CI ?28%; 46%) against SARS-CoV-2 infection and 70% (95% CI ?44%; 96%) against mortality. Among boostered residents (N = 55), there were 25 cases in the first week after receiving the booster dose, declining to 5 in the second and none in the third week.ConclusionVE of primary vaccination in residents of LTCF was very low against SARS-CoV-2 infection and moderate against mortality. There were few cases at 2 weeks after the booster dose and no deaths, despite the presence of susceptible residents. These data are consistent with the positive impact of the booster vaccination in curbing transmission. Timely booster vaccination in residents of LTCF is therefore important.     

Hesitancy to receive the novel coronavirus vaccine and potential influences on vaccination among a cohort of healthcare workers in the Democratic Republic of the Congo

Hesitancy to receive the COVID-19 vaccine among healthcare workers (HCWs) in low-resource settings, such as the Democratic Republic of the Congo (DRC), is a major global health challenge. This study identifies changes in willingness to receive vaccination among 588 HCWs in the DRC and reported influences on COVID-19 vaccination intentions. Up to 25 repeated measures were collected from participants between August 2020 to August 2021. Among the overall cohort, between August 2020 and mid-March 2021, the proportion of HCWs in each period of data collection reporting COVID-19 vaccine hesitancy ranged from 8.6% (95% CI: 5.97, 11.24) to 24.3% (95% CI: 20.12, 28.55). By early April 2021, the proportion reporting hesitancy more than doubled (52.0%; 95% CI: 46.22, 57.83). While hesitancy in the cohort began to decline by late-June 2021, 22.6% (95% CI: 18.05, 27.18) respondents indicated hesitancy in late-August 2021 which remains greater than the proportion of hesitancy at any time prior to early-March 2021. Patterns in reported influences on COVID-19 vaccination were varied with the proportion reporting some influences (e.g., no serious side effects, country of vaccine production) remaining stable throughout the year and other factors (e.g., recommendation of Ministry of Health, ease of vaccination) falling in popularity among respondents. Agreement that the national vaccination schedule should be followed apart from the COVID-19 vaccine remained high among respondents throughout the study period. This study shows that, among a cohort of HCWs in the DRC who have likely been influenced by regional, national, and global factors, COVID-19 vaccine hesitancy has fluctuated during the pandemic and should not be treated as a static factor. Additional research to determine which factors most influence HCWs’ willingness to receive the COVID-19 vaccine offers opportunities to reduce vaccine hesitancy among this important population through tailored public health messaging.     

Temporal trends and determinants of COVID-19 vaccine coverage and series initiation during pregnancy in Ontario,Canada, December 2020 to December 2021: A population-based retrospective cohort study

BackgroundPopulation-based COVID-19 vaccine coverage estimates among pregnant individuals are limited. We assessed temporal patterns in vaccine coverage (≥1 dose before or during pregnancy) and evaluated factors associated with vaccine series initiation (receiving dose 1 during pregnancy) in Ontario, Canada.MethodsWe linked the provincial birth registry with COVID-19 vaccination records from December 14, 2020 to December 31, 2021 and assessed coverage rates among all pregnant individuals by month, age, and neighborhood sociodemographic characteristics. Among individuals who gave birth since April 2021—when pregnant people were prioritized for vaccination—we assessed associations between sociodemographic, behavioral, and pregnancy-related factors with vaccine series initiation using multivariable regression to estimate adjusted risk ratios (aRR) and risk differences (aRD) with 95% confidence intervals (CI).ResultsAmong 221,190 pregnant individuals, vaccine coverage increased to 71.2% by December 2021. Gaps in coverage across categories of age and sociodemographic characteristics decreased over time, but did not disappear. Lower vaccine series initiation was associated with lower age (<25 vs. 30–34 years: aRR 0.53, 95%CI 0.51–0.56), smoking (vs. non-smoking: 0.64, 0.61–0.67), no first trimester prenatal care visit (vs. visit: 0.80, 0.77–0.84), and residing in neighborhoods with the lowest income (vs. highest: 0.69, 0.67–0.71). Vaccine series initiation was marginally higher among individuals with pre-existing medical conditions (vs. no conditions: 1.07, 1.04–1.10).ConclusionsCOVID-19 vaccine coverage among pregnant individuals remained lower than in the general population, and there was lower vaccine initiation by multiple characteristics.     

Evaluation of post-introduction COVID-19 vaccine effectiveness: Summary of interim guidance of the World Health Organization

Phase 3 randomized-controlled trials have provided promising results of COVID-19 vaccine efficacy, ranging from 50 to 95% against symptomatic disease as the primary endpoints, resulting in emergency use authorization/listing for several vaccines. However, given the short duration of follow-up during the clinical trials, strict eligibility criteria, emerging variants of concern, and the changing epidemiology of the pandemic, many questions still remain unanswered regarding vaccine performance. Post-introduction vaccine effectiveness evaluations can help us to understand the vaccine's effect on reducing infection and disease when used in real-world conditions. They can also address important questions that were either not studied or were incompletely studied in the trials and that will inform evolving vaccine policy, including assessment of the duration of effectiveness; effectiveness in key subpopulations, such as the very old or immunocompromised; against severe disease and death due to COVID-19; against emerging SARS-CoV-2 variants of concern; and with different vaccination schedules, such as number of doses and varying dosing intervals. WHO convened an expert panel to develop interim best practice guidance for COVID-19 vaccine effectiveness evaluations. We present a summary of the interim guidance, including discussion of different study designs, priority outcomes to evaluate, potential biases, existing surveillance platforms that can be used, and recommendations for reporting results.     

Safety,immunogenicity, and immune persistence of two inactivated COVID-19 vaccines replacement vaccination in China: An observational cohort study

BackgroundTo mitigate a national shortage of WIBP-CorV COVID-19 vaccine, China’s regulator approved administering BBIBP-CorV after WIBP-CorV for completion of a primary series. In a pragmatic observational study, we compared immunogenicity and safety of a primary series of WIBP-CorV followed by BBIBP-CorV with a primary series of two doses of BBIBP-CorV.MethodsWe invited healthy 18–59-years-old adults who had already received either WIBP-CorV or BBIBP-CorV as their first dose in a primary series to participate in this observational cohort study. Subjects who had received WIBP-CorV as their first dose became the observation group; subjects who had received BBIBP-CorV as their first dose became the control group. All participants received BBIBP-CorV as their second dose. We obtained sera 1, 2, and 6 months after second doses for nAb titer measurement by micro-neutralization cytopathic effect assay with SARS-CoV-2 strain HB01, standardized with WHO International Standard for anti-SARS-CoV-2 immunoglobulin. Safety was assessed for the 7 days after administration of second doses.ResultsBetween March and December 2021, 275 subjects were included in the observation group and 133 in the control group. Neutralizing seropositivity (≥1:4) rates were 98.91 % and 99.25 % at 1 month and 53.16 % and 70.69 % at 6 months. One-month geometric mean titers (GMTs) were 21.33 and 22.45; one-month geometric mean concentrations (GMCs) were 227.71 IU/mL and 273.27 IU/mL. One to two months after vaccination, observation group seropositivity rates and titers were not significantly different to the control group’s. Adverse reaction rates were 11.27 % and 18.80 %, all mild or moderate in severity.ConclusionsBoth primary series were immunogenic; immunogenicity of WIBP-CorV followed by BBIBP-CorV was not different than immunogenicity following two doses of BBIBP-CorV for two months after vaccination; safety profiles were acceptable for both regimens. BBIBP-CorV can be used to complete a primary series that started with WIBP-CorV.     

Cross-sectional study of hepatitis B antibody status in health care workers immunized as children at an academic medical center in Wisconsin

Individuals who received the hepatitis B vaccine series as young children are entering the healthcare workforce. Our study measured the persistence of antibody to the hepatitis B surface antigen (anti-HBs) at time of employment. Among 986 individuals born in 1991 or more recently with documentation of completion of the hepatitis B vaccine series, 51% had anti-HBs < 10mIU/ml. Of these 507 healthcare workers, 446 (88%) received documented fourth dose of hepatitis B vaccine followed by another anti-HBs ≥ 28 days post vaccination; 11% (50/446 or 5% of the total population) did not mount an anamnestic response. The non-responders were more likely to be male or complete the vaccine series prior to age 7 months. Measuring anti-HBs at the time of hire in this population of healthcare workers who had documentation of hepatitis B series completion as young children may be unnecessary because of the high rate of hepatitis B vaccine protection.     

2017－2018年流感流行季儿童接种流感疫苗效果社区队列研究

目的 评价6~72月龄儿童接种流感疫苗效果。方法 采用社区队列研究设计,2017年10-12月,从浙江省永康和义乌两市10家儿童接种门诊招募了1 752名6~72月龄儿童。每名儿童入队列后,完成知情同意和问卷调查,并随访至2018年4月30日,观察记录流感样病例（ILI）发病、门诊就诊和自行服药及流感疫苗接种情况。以ILI、门诊就诊和自行服药的发生次数为因变量,采用广义线性模型（GLM）拟合,估算流感疫苗效果（VE）值。结果 1 752名儿童中,男童925名（52.80%）,月龄M=30.00月,累计随访观察308 166人天,平均每天有5.27‰发生ILI、3.41‰因ILI去医院门诊就诊、1.45‰因ILI自行服药治疗;共有643名儿童接种了流感疫苗,与未接种儿童相比,流感疫苗对ILI、门诊就诊和自行服药的VE值分别为23.5%（95% CI：15.1%~31.1%）、19.3%（95% CI：8.2%~29.1%）和25.8%（95% CI：9.3%~39.3%）。643名接种儿童,接种后与接种前比,流感疫苗针对36~72月龄儿童ILI、门诊就诊和自行服药的VE值分别为31.9%（95% CI：12.7%~46.9%）、32.6%（95% CI：8.6%~50.3%）和44.3%（95% CI：11.9%~64.8%）,而对6~35月龄儿童,VE值均无统计学意义。2016-2018年流感疫苗不同接种暴露VE值评估,两个流感流行季均有接种史的,仅2017-2018年流感流行季有接种史的,流感疫苗VE值,均有统计学意义;仅2016-2017年流感流行季有接种史的,VE值均无统计学意义。结论 流感流行季接种流感疫苗一定程度可预防ILI发病、门诊就诊和自行服药,且对36~72月龄儿童保护效果优于6~35月龄儿童。