“The concern is whether SARS-CoV-2 variants may reduce the efficacy of current vaccines that were designed to protect against the original SARS-CoV-2 strain at the beginning of the pandemic,” said Barouch, senior author of the study and also Professor of Medicine at Harvard Medical School.
‘Immune response triggered by neutralizing antibodies against the B.1.1351 and P.1 strains was less when compared to the response against the original strain.’
Barouch, Director of BIDMC’s Center for Virology and Vaccine Research, and colleagues sought to explore the immunogenicity of Ad26.COV2. S vaccine against the original viral strain (WA1/2020) and variants B.1.1351, B.1.1.7, P.1, CAL.20C. They observed about 20 volunteers between the ages of 18 and 55 who were all participants of a larger multicenter, randomized, double-blind, placebo-controlled Phase 1/2a study.
Various methods were used to assess antibody and cellular immune responses.
They observed that there were reduced immune responses by neutralizing antibodies against the B.1.1351 and P.1 strains compared to the antibody responses against WA1/2020.
Based on the other outcomes from Phase 3 clinical trials, the experts hypothesized that levels of neutralizing antibodies were reduced against the variants but the non-neutralizing antibodies and/or T cell responses could contribute to the protection.
“These findings, therefore, have important implications for vaccine protection against SARS-CoV-2 variants of concern,” Barouch added.