mRNA-1273 and BNT162b2 mRNA vaccines have reduced neutralizing activity against the SARS-CoV-2 Omicron variant

We used a live virus neutralization assay to examine the neutralizing activity of the Omicron against mRNA vaccine-induced antibody responses. Following 2-4 weeks after primary series of vaccinations, we observed a 30-fold reduction in neutralizing activity against Omicron.

Six months after the initial two vaccine doses, sera from naïve vaccinated subjects showed no neutralizing activity against the Omicron. In contrast, COVID-19 recovered individuals six months after receiving the primary series of vaccinations show a 22-fold reduction with majority of the subjects retaining neutralizing antibody responses. In naïve individuals following a booster shot (3rd dose), we observed a 14-fold reduction in neutralizing activity against Omicron and over 90% of subjects show neutralizing activity.