With input from Dr Monica Vasudev

Increased breakthrough rates of COVID-19 variants of concern in BNT162b2 mRNA vaccinated people

The BNT162b2 mRNA vaccine has shown high levels of protection, but there is still apprehension that several variants of concerns (VOCs) can overcome the immune defenses that the vaccine generates.

Neutralization assays have shown some amount of reduction in neutralization of VOCs B.1.1.7 and B.1.351; however, the relevance of these assays in real life scenario is still not clear.

A case-control study was carried out that evaluated if BNT162b2 vaccine recipients with confirmed SARS-CoV-2 infection had a higher likelihood of getting infected with B.1.1.7 or B.1.351 compared with the unvaccinated individuals. Vaccine recipients infected at least one week after the second dose were disproportionally infected with B.1.351 (odds ratio of 8:1).

Those infected two weeks after the first dose up till one week following the second dose, were found to be disproportionally infected by B.1.1.7 (odds ratio of 26:10). This points to diminished vaccine effectiveness against both VOCs under different dosing or timing conditions.

The incidence of B.1.351 is low in Israel and vaccine effectiveness is high against B.1.1.7, among those fully vaccinated.

Overall, the vaccine breakthrough infection is more frequently seen with both VOCs; however, mass-vaccination with two doses in combination with non-pharmaceutical interventions can help curb their spread.

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA