COVID-19 vaccine uptake and effectiveness in adults aged 50 years and older in Wales UK: a 1.2m population data-linkage cohort approach

Dimensions of equality in uptake of COVID-19 vaccination in Wales, UK: A multivariable linked data population analysis

Vaccination has proven to be effective at preventing severe outcomes of COVID-19 infection, and uptake in the population has been high in Wales. However, there is a risk that high-level vaccination coverage statistics may mask hidden inequalities in under-served populations, many of whom may be at increased risk of severe outcomes of COVID-19 infection. The study population included 1,436,229 individuals aged 18 years and over, alive and residence in Wales as at 31st July 2022, and excluded immunosuppressed or care home residents. We compared people who had received one or more vaccinations to those with no vaccination using linked data from nine datasets within the Secure Anonymised Information Linkage (SAIL) databank. Multivariable analysis was undertaken to determine the impact of a range of sociodemographic characteristics on vaccination uptake, including ethnicity, country of birth, severe mental illness, homelessness and substance use. We found that overall uptake of first dose of COVID-19 vaccination was high in Wales (92.1 %), with the highest among those aged 80 years and over and females. Those aged under 40 years, household composition (aOR 0.38 95 %CI 0.35-0.41 for 10+ size household compared to two adult household) and being born outside the UK (aOR 0.44 95 %CI 0.43-0.46) had the strongest negative associations with vaccination uptake. This was followed by a history of substance misuse (aOR 0.45 95 %CI 0.44-0.46). Despite high-level population coverage in Wales, significant inequalities remain across several underserved groups. Factors associated with vaccination uptake should not be considered in isolation, to avoid drawing incorrect conclusions. Ensuring equitable access to vaccination is essential to protecting under-served groups from COVID-19 and further work needs to be done to address these gaps in coverage, with focus on tailored vaccination pathways and advocacy, using trusted partners and communities.

Vaccine efficacy against SARS-CoV-2 for Pfizer BioNTech, Moderna, and AstraZeneca vaccines: a systematic review

The purpose of this systematic review was to report on the vaccine efficacy (VE) of three SARS-CoV-2 vaccines approved by Health Canada: Pfizer BioNTech, Moderna, and AstraZeneca. Four databases were searched for primary publications on population-level VE. Ninety-two publications matched the inclusion criteria, and the extracted data were separated by vaccine type: mRNA vaccines (Pfizer and Moderna) and the AstraZeneca vaccine. The median VE for PCR-positive patients and various levels of clinical disease was determined for the first and second doses of both vaccine types against multiple SARS-CoV-2 variants. The median VE for PCR-positive infections against unidentified variants from an mRNA vaccine was 64.5 and 89%, respectively, after one or two doses. The median VE for PCR-positive infections against unidentified variants from the AstraZeneca vaccine was 53.4 and 69.6%, respectively, after one or two doses. The median VE for two doses of mRNA for asymptomatic, symptomatic, and severe infection against unidentified variants was 85.5, 93.2, and 92.2%, respectively. The median VE for two doses of AstraZeneca for asymptomatic, symptomatic, and severe infection against unidentified variants was 69.7, 71, and 90.2%, respectively. Vaccine efficacy numerically increased from the first to the second dose, increased from the first 2 weeks to the second 2 weeks post-vaccination for both doses, but decreased after 4 months from the second dose. Vaccine efficacy did not differ by person's age.

Assessing the coverage and timeliness of coronavirus vaccination among people experiencing homelessness in Wales, UK: a population-level data-linkage study

BACKGROUND

People experiencing homelessness have elevated morbidity, increasing their risk of COVID-19 related complications and mortality. Achieving high vaccination coverage in a timely manner among homeless populations was therefore important during the mass vaccination programme in Wales to limit adverse outcomes. However, no systematic monitoring of vaccinations among people experiencing homelessness in Wales has been undertaken.

METHODS

Retrospective cohort analysis was conducted using de-identified administrative data. Study cohort members were adults (≥ 18 years old) living in Wales on the 2 December 2020 and who had recently experienced homelessness, defined as experiencing homelessness between 1 July 2020 and 2 December 2020. The outcome of interest was first coronavirus vaccine dose. Follow-up started on 2 December 2020, and ended if the participant died, had a break in address history > 30 days, reached the end of follow up (30 November 2021), or had the outcome of interest. Median-time-to-vaccination was used as a crude measure of 'timeliness' of vaccine uptake. To account for competing risk of death prior to vaccination, vaccine coverage was described using cumulative incidence at 350-days, and at 50-day increments over follow-up (2 December 2020 to 17 November 2021). As a benchmark, all time-to-event measures were generated for the adult population in Wales with similar baseline individual and residential characteristics as the study cohort.

RESULTS

1,595 people with recent experiences of homelessness were identified and included in analysis. The study cohort were disproportionately male (68.8%) and concentrated in the most deprived areas in Wales. Median time-to-vaccination for the study cohort was 196 days (95% CI.: 184-209 days), compared to 141 days (95% CI.: 141-141 days) among the matched adult population in Wales. Cumulative incidence of vaccination after 350-days of follow-up was 60.4% (95% CI.: 57.8-62.8%) among the study cohort, compared to 81.4% (95% CI.: 81.3-81.5%) among the matched adult population. Visual analysis of cumulative incidence over time suggests that vaccine inequality, i.e., difference between study cohort and matched adult population, peaked after 200-days of follow-up, and declined slightly until last follow-up at 350-days.

CONCLUSIONS

Despite being prioritised for vaccination, people experiencing homelessness in Wales appear to have been under-engaged, leading to lower vaccination coverage and greater time unvaccinated, potentially increasing their risk of COVID-19 complications and mortality.

An external validation of the QCOVID3 risk prediction algorithm for risk of hospitalisation and death from COVID-19: An observational, prospective cohort study of 1.66m vaccinated adults in Wales, UK

INTRODUCTION

At the start of the COVID-19 pandemic there was an urgent need to identify individuals at highest risk of severe outcomes, such as hospitalisation and death following infection. The QCOVID risk prediction algorithms emerged as key tools in facilitating this which were further developed during the second wave of the COVID-19 pandemic to identify groups of people at highest risk of severe COVID-19 related outcomes following one or two doses of vaccine.

OBJECTIVES

To externally validate the QCOVID3 algorithm based on primary and secondary care records for Wales, UK.

METHODS

We conducted an observational, prospective cohort based on electronic health care records for 1.66m vaccinated adults living in Wales on 8th December 2020, with follow-up until 15th June 2021. Follow-up started from day 14 post vaccination to allow the full effect of the vaccine.

RESULTS

The scores produced by the QCOVID3 risk algorithm showed high levels of discrimination for both COVID-19 related deaths and hospital admissions and good calibration (Harrell C statistic: ≥ 0.828).

CONCLUSION

This validation of the updated QCOVID3 risk algorithms in the adult vaccinated Welsh population has shown that the algorithms are valid for use in the Welsh population, and applicable on a population independent of the original study, which has not been previously reported. This study provides further evidence that the QCOVID algorithms can help inform public health risk management on the ongoing surveillance and intervention to manage COVID-19 related risks.

Using data linkage to monitor COVID-19 vaccination: development of a vaccination linked data repository

The COVID-19 Vaccination Linked Data Repository (CVLDR) was established in 2021 to assist with the implementation and management of the COVID-19 vaccination program in the State of Western Australia (WA). The CVLDR contains a number of datasets including the Australian Immunisation Register, hospital admissions, emergency department attendances, notifiable infectious disease, and laboratory data. Datasets in the CVLDR are linked using a probabilistic method at the WA Department of Health. Quality assurance mechanisms have been established to identify and mitigate potential errors in the linkage. Each of the datasets has varying degrees of data quality and completeness, however most are of high standard, underpinned by legislation. The linking of the datasets within the CVLDR has allowed for increased public health utility in the immunisation program including the areas of vaccine safety, effectiveness, and coverage.

Determinants of COVID-19 vaccine uptake among healthcare professionals and the general population in Cyprus: A web-based cross-sectional survey

OBJECTIVE

This study aims to examine the factors influencing COVID-19 vaccine uptake among healthcare professionals (HCPs) and the general population in Cyprus.

METHODS

A web-based cross-sectional study was conducted (November 2021-January 2022), using a self-administered, anonymous questionnaire to collect information covering a wide range of potential determinants including sociodemographic and health-related characteristics, trust in the healthcare system, satisfaction with it, utilization of preventive healthcare services, COVID-19 vaccination information and general vaccination knowledge.

RESULTS

A total of 2582 participants completed the survey. Overall, 53.5% of participants representing the general population, and 70.0% of the HCPs received the COVID-19 vaccination. We found that as the age increases by 1 year among the general population, the odds of being vaccinated against COVID-19 increase by 1.02 units (95% 1.00, 1.03, p= 0.035). In addition, participants among the general population with increased trust in national healthcare authorities' guidelines (OR = 3.96, 95% CI: 3.41, 4.61), and increased vaccination knowledge scores (OR = 1.11, 95% CI: 1.05, 1.18) were significantly more likely to be vaccinated, while those who had underage children living in the household were significantly less likely to be vaccinated against COVID-19 (OR = 0.68, 95% CI: 0.50, 0.91). Furthermore, male HCPs (OR = 1.91, 95% CI: 1.01, 3.59), and those who reported increased trust in national healthcare authorities' guidelines (OR = 5.38, 95% CI: 3.65, 7.95) were significantly more likely to be vaccinated.

CONCLUSION

Public health policymakers can use national campaigns and long-term planning to build public trust in national healthcare authorities and raise awareness about the benefits of vaccination. Such strategies could pave the way for adequate vaccine uptake and prepare the public for unfavourable scenarios, such as future pandemics.