Work

Effectiveness of BNT162b2 and Ad.COV2.S vaccines against COVID-19-related hospitalisation among adult members of a private health insurance scheme in South Africa during the Delta and Omicron periods: a test-negative case-control study

Year: 2023

Type: preprint

Abstract: Background COVID-19 vaccine effectiveness estimates from Africa are limited. These data can guide decisions on selecting priority groups in vaccine programs. This study estimated VE for BNT162b2 and Ad26.COV2.S against COVID-19-related hospitalisation, stratified by age group, time since vaccination and HIV-infection status for three SARS-CoV-2 surges in South Africa (driven by the delta, omicron BA.1 and omicron BA.4/5 variants) among ≥ 18 years old. Methods We applied a test-negative case-control design to hospitalisations for acute respiratory infections amongst members of a large medical scheme. Individuals receiving a single dose of Ad26.COV2S or two-doses of BNT162b2 were considered fully vaccinated and compared to unvaccinated individuals. Logistic regression models adjusted for age, comorbidities and documentation of previous SARS-CoV-2 infection, were used to calculate VE. Results BNT162b2 was protective against COVID-19-related hospitalisation for all variant periods (VE 89.3% (95% CI, 85.9–91.9) for delta, reduced to 31.4% (95% CI, 19.1–41.9) and 22.7% (95% CI, 2.2–38.9) for omicron BA.1 and BA.4/5 respectively). VE estimates for Ad26.COV2.S, although lower than BNT162b2, were protective for all periods (48.8% (95% CI, 39.6–56.5), 19.8% (95% CI, 5.8–31.6) and 45.0% (95% CI, 29.8–57.0)). Protection was similar amongst those ≥ 60 years and younger age groups, and among people living with HIV and HIV-uninfected individuals. Conclusion Vaccination with either BNT162b2 or Ad26.COV2.S offered significant protection against COVID-19-related hospitalisation in PLWH and adults over the age of 60 years and therefore is an effective means of reducing severe outcomes in these high-risk populations in South Africa. VE against BA.4/5 waned with time since vaccination suggesting boosters may be necessary.

Source: Research Square

DOI: 10.21203/rs.3.rs-3202606/v1