Evaluation of BNT162b2 Vaccine Effectiveness in Galicia, Northwest Spain

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.

COVID-19 vaccine effectiveness in children by age groups. A population-based study in Galicia, Spain

BACKGROUND

Studies on vaccine effectiveness (VE) against COVID-19 in the pediatric population are outgoing. We aimed to quantify VE against SARS-CoV-2 in two pediatric age groups, 5-11 and 12-17-year-old, while considering vaccine type, SARS-CoV-2 variant, and duration of protection.

METHODS

A population-based test-negative control study was undertaken in Galicia, Spain. Children 5-11-year-old received the Comirnaty® (Pfizer, US) vaccine, while those aged 12-17-year-old received the Comirnaty® (Pfizer, US) or SpikeVax® (ModernaTX, Inc) vaccine. Participants were categorized into unvaccinated (0 doses or one dose with <14 days since vaccination), partially vaccinated (only one dose with ≥14 days, or two doses with <14 days after the second dose administration), and fully vaccinated (two doses with ≥14 days after the second injection). Adjusted odds ratios (OR) and their 95% confidence intervals (CI) were estimated using multiple logistic regression models. VE was calculated as (1-OR) * 100. Stratified and sensitivity analyses were performed.

RESULTS

In the fully vaccinated 5-11-year-old children, VE against the Omicron variant was 44.1% (95% CI: 38.2%-49.4%). In the fully vaccinated 12-17-year-old individuals, VE was 83.4% (95% CI: 81.2%-85.3%) against Delta and 74.8% (95% CI: 58.5%-84.9%) against Omicron. Comirnaty® and SpikeVax® vaccines showed a similar magnitude of VE against Delta [Comirnaty® VE: 81.9% (95% CI: 79.3%-84.1%) and SpikeVax® VE: 85.3% (95% CI: 81.9%-88.1%)]. Comirnaty® (Pfizer, US; VE: 79.7%; 95% CI: 50.7%-92.4%) showed a slightly higher magnitude of protection against Omicron than SpikeVax® (ModernaTX, Inc), yet with an overlapping CI (VE: 74.3%; 95% CI: 56.6%-84.9%). VE was maintained in all age subgroups in both pediatric populations, but it declined over time.

CONCLUSIONS

In Galicia, mRNA VE was moderate against SARS-CoV-2 infections in the 5-11-year-old populations, but high in older children. VE declined over time, suggesting a potential need for booster dose schedules.

Effectiveness of COVID-19 vaccine booster in the general population and in subjects with comorbidities. A population-based study in Spain

BACKGROUND

Research on the effectiveness of COVID-19 booster-based vaccine schedule is ongoing and real-world data on vaccine effectiveness (VE) in comorbid patients are limited. We aimed to estimate booster dose VE against SARS-CoV-2 infection and COVID-19 severity in the general population and in comorbid patients.

METHOD

A retrospective test-negative control study was undertaken in Galicia-Spain (December 2020-November 2021). VE and 95% confidence interval (CI) were estimated using multivariate logistic regression models.

RESULTS

1,512,415 (94.13%) negative and 94,334 (5.87%) positive SARS-CoV-2 test results were included. A booster dose of COVID-19 vaccine is associated with substantially higher protection against SARS-CoV-2 infection than vaccination without a booster [VE_boosted = 87% (95%CI: 83%; 89%); VE_non-boosted = 66% (95%CI: 65%; 67%)]. The high VE was observed in all ages, but was more pronounced in subjects older than 65 years. VE against COVID-19 severity was analyzed in a mixed population of boosted and non-boosted individuals and considerable protection was obtained [VE: hospitalization = 72% (95%CI: 68%; 75%); intensive care unit administration = 83% (95%CI: 78%; 88%), in-hospital mortality = 66% (95%CI: 53%; 75%)]. Boosted comorbid patients are more protected against SARS-CoV-2 infection than those who were non-boosted. This was observed in a wide range of major diseases including cancer (81% versus 54%), chronic obstructive pulmonary disease (84% versus 61%), diabetes (84% versus 65%), hypertension (82% versus 65%) and obesity (91% versus 67%), among others.

CONCLUSIONS

A booster dose of COVID-19 vaccine increases the protection against SARS-CoV-2 infection and COVID-19 severity in the general population and in comorbid patients.