COVID-19: Delta variant may have greater ability to evade immunity from vaccines

The delta variant of SARS-CoV-2 may be more successful in evading the protective response of vaccines from Pfizer and AstraZeneca, indicates a study that does not include the new omicron and published by Plos.

A team of British scientists, led by the University of Glasgow, did an analysis to quantify the ability of the alpha, beta and delta variants to evade the immunity induced by these two vaccines.

The study indicates that both preparations conferred protection against variants of the COVID-19, but they observed “less antibody neutralization” of the beta and delta variants.

In the sample of vaccinated individuals, the delta variant reduced the immune response in recipients of the Pfizer and Astra Zeneca vaccine by 4.31 and 5.11 times respectively, Plos indicates.

The research was not designed to directly measure vaccine efficacy, although it was in line with recent Public Health England findings of slightly lower efficacy against the delta variant than previous ones.

The researchers used serum samples from 156 people who had received two doses and 50 with only one, the publication summarizes.

The team exposed the SARS-CoV-2 proteins in a virus model system to sera from vaccinated people and observed the response of the antibodies, measuring how well they prevented each variant from infecting cells.

Vaccines remain highly effective in preventing severe infection and death, but the authors noted that “ongoing monitoring of neutralization against newer variants is indicated in conjunction with vaccine efficacy studies, as the virus remains evolving over time, especially in vulnerable groups ”.

Mutations change the shape of the coronavirus spike protein (the one it uses to enter human cells), preventing antibody recognition and allowing the virus to escape vaccine-induced immunity.