Efficacy of Covid-19 vaccine against B.1.617.2 (delta) mutants

July 21, 2021.

DOI: 10.1056 / NEJMoa2108891

Commentary

This study will investigate the efficacy of BNT162b2 and ChAdOx1nCoV-19 vaccines against mutants. Data on all symptomatic sequenced cases of Covid-19 in the UK were used to estimate the proportion of cases with either variant depending on the vaccination status of the patient.

The results showed that the efficacy of the vaccines (BNT162b2 and ChAdOx1 nCoV-19) after a single dose was similar for both vaccines, with delta mutants (30.7%; 95% confidence interval [CI], 25.2-35.7) and alpha mutants (48.7%; 95% CI, 45.5-51.7). The results were similar for both vaccines.

For the BNT162b2 vaccine, the efficacy of two doses was 93.7% (95% CI, 91.6-95.3) in persons with the alpha variant and 88.0% (95% CI, 85.3-90.1) in persons with the delta variant, and for the ChAdOx1 nCoV-19 vaccine, the efficacy of two doses was reported to be 74.5% (95% CI, 68.4-79.4) in people with the alpha variant and 67.0% (95% CI, 61.3-71.8) in people with the delta variant.

These concluded that there was only a small difference in vaccine efficacy in the delta variant compared to the alpha variant after two doses of vaccine. The absolute difference in vaccine efficacy is more pronounced after the first dose.

(The study was funded by the UK Public Health Service.)