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Effectiveness of BNT162b2 and Ad26.COV2.S vaccines against COVID-19-related hospitalisation amongst adult members of a private health insurance plan in South Africa during the Delta and Omicron periods: A test-negative case-control study

Year: 2025

Type: article

Abstract: 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. We applied a test-negative case-control design to hospitalisations for acute respiratory infections amongst members of a medical insurance plan during the delta (9 May 2021–18 September 2021), omicron BA.1 (28 November 2021–5 February 2022), and BA.4/5 (17 April 2022–28 May 2022) variant periods. All data, including vaccination history, were extracted from insurance plan claims. Logistic regression models adjusted for age, comorbidities, time since vaccination, income level and documentation of previous SARS-CoV-2 infection, were used to calculate VE. 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) for delta, omicron BA.1, and BA.4/5 respectively). Protection against severe infection was shown in those ≥60 years and younger age groups, as well as in people living with HIV (PLWH) and HIV-uninfected individuals. Vaccination offered significant protection against COVID-19-related hospitalisation in PLWH and the elderly, and is therefore 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. • BNT162b2 and Ad26.COV2.S were protective against COVID-19-related hospitalisation for all variant periods. • Protection was shown in the ≥60 year age group for BNT162b2 (all variant periods) and for Ad.COV2.S (BA.4/5 period). • Protection was shown in the <60 year age group for BNT162b2 (delta, BA.1 periods) and for Ad.COV2.S (delta, BA.4/5 periods). • Protection was shown in HIV-uninfected individuals for BNT162b2 (all variant periods) and Ad.COV2.S (delta, BA.4/5). • In people living with HIV (PLWH), protection was shown for BNT162b2 (delta period) and Ad.COV2.S (delta, BA.1 periods). • Vaccination is effective in reducing severe outcomes in high-risk populations in South Africa.

Source: Vaccine

DOI: 10.1016/j.vaccine.2025.127068