Protective Duration of ChAdOx1 and BNT162b2 Vaccines Against SARS-CoV-2 Infection

A limited number of studies have addressed the protective duration of coronavirus disease 2019 (COVID-19) vaccines following primary and booster doses in Saudi Arabia. Therefore, this study aimed to evaluate the protective duration of primary and booster doses of BNT162b2 and ChAdOx1 COVID-19 vaccine batches in Saudi Arabia.

A cross-sectional study was conducted from 1 January to 31 December, 2021. The study included 53,354 people infected with severe acute respiratory syndrome coronavirus-2 2 weeks or more after receiving at least a primary vaccination of either the ChAdOx1 or BNT162b2 vaccine.

The total median protective duration of both primary COVID-19 vaccinations was 134 days. Heterologous primary vaccination (ChAdOx1 followed by BNT162b2) showed a significantly higher median protective duration of 142 days. The results show that the total median protective duration of the first booster doses of COVID-19 vaccines was 57 days. ChAdOx1 batch code C1 was found to have the most extended protective duration of 173 days (range 163-192 days).

The current study revealed that the median protective duration of ChAdOx1 and BNT162b2 COVID-19 primary vaccination regimens administered in Saudi Arabia in 2021 was 134 days and that heterologous primary vaccination (ChAdOx1→BNT162b2) exhibited a significantly higher protective duration than other vaccination regimens.