Assessing COVID-19 Vaccine Uptake and Effectiveness Through the North West London Vaccination Program: Retrospective Cohort Study

Abstract

Background On March 11, 2020, the World Health Organization declared SARS-CoV-2, causing COVID-19, as a pandemic. The UK mass vaccination program commenced on December 8, 2020, vaccinating groups of the population deemed to be most vulnerable to severe COVID-19 infection. Objective This study aims to assess the early vaccine administration coverage and outcome data across an integrated care system in North West London, leveraging a unique population-level care data set. Vaccine effectiveness of a single dose of the Oxford/AstraZeneca and Pfizer/BioNTech vaccines were compared. Methods A retrospective cohort study identified 2,183,939 individuals eligible for COVID-19 vaccination between December 8, 2020, and February 24, 2021, within a primary, secondary, and community care integrated care data set. These data were used to assess vaccination hesitancy across ethnicity, gender, and socioeconomic deprivation measures (Pearson product-moment correlations); investigate COVID-19 transmission related to vaccination hubs; and assess the early effectiveness of COVID-19 vaccination (after a single dose) using time-to-event analyses with multivariable Cox regression analysis to investigate if vaccination independently predicted positive SARS-CoV-2 in those vaccinated compared to those unvaccinated. Results In this study, 5.88% (24,332/413,919) of individuals declined and did not receive a vaccination. Black or Black British individuals had the highest rate of declining a vaccine at 16.14% (4337/26,870). There was a strong negative association between socioeconomic deprivation and rate of declining vaccination (r=–0.94; P=.002) with 13.5% (1980/14,571) of individuals declining vaccination in the most deprived areas compared to 0.98% (869/9609) in the least. In the first 6 days after vaccination, 344 of 389,587 (0.09%) individuals tested positive for SARS-CoV-2. The rate increased to 0.13% (525/389,243) between days 7 and 13, before then gradually falling week on week. At 28 days post vaccination, there was a 74% (hazard ratio 0.26, 95% CI 0.19-0.35) and 78% (hazard ratio 0.22, 95% CI 0.18-0.27) reduction in risk of testing positive for SARS-CoV-2 for individuals that received the Oxford/AstraZeneca and Pfizer/BioNTech vaccines, respectively, when compared with unvaccinated individuals. A very low proportion of hospital admissions were seen in vaccinated individuals who tested positive for SARS-CoV-2 (288/389,587, 0.07% of all patients vaccinated) providing evidence for vaccination effectiveness after a single dose. Conclusions There was no definitive evidence to suggest COVID-19 was transmitted as a result of vaccination hubs during the vaccine administration rollout in North West London, and the risk of contracting COVID-19 or becoming hospitalized after vaccination has been demonstrated to be low in the vaccinated population. This study provides further evidence that a single dose of either the Pfizer/BioNTech vaccine or the Oxford/AstraZeneca vaccine is effective at reducing the risk of testing positive for COVID-19 up to 60 days across all age groups, ethnic groups, and risk categories in an urban UK population.

Effectiveness of COVID-19 vaccine in preventing infection and disease severity: a case-control study from an Eastern State of India

“…The chance of getting infection and having COVID-19 increases with age, so also the VE [ 27 , 28 ]. The participants in all the UK studies were comparatively older than our study except for the study reported from north-west London [ 26 ]. Lopez Bernal et al .…”

“…VIVALDI cohort study [25] which requited older adults (≥65 years) of UK as study participants reported 68% risk reduction (at 35 to 48 days) of contracting SARS-CoV-2 following single jab of Oxford-AstraZeneca vaccine. Even higher risk reduction of infection [74% (28 day onwards)] following single standard dose of Oxford-AstraZeneca vaccine was claimed by Glampson et al [26] which enrolled participants of all ages (≥16 years) in their study. Both these observations were higher compared to us.…”

“…Generally, the VE of disease prevention is higher than the VE of infection prevention [29]. Second, unlike us, Shrotri et al [25] and Glampson et al [26] adopted a cohort study design for VE assessment. Moreover, ethnic variations might have played a role.…”

“…Even higher risk reduction of infection (74% (28 days onwards)) following a single standard dose of Oxford-AstraZeneca vaccine was claimed by Glampson et al . [ 26 ] which enrolled participants of all ages (≥16 years) in their study. Both these observations were higher compared to us.…”

“…[ 25 ] and Glampson et al . [ 26 ] adopted a cohort study design for VE assessment. Moreover, ethnic variations might have played a role.…”