Two doses of the CoronaVac COVID-19 vaccine offer 83.5% protection against symptomatic disease; however, the antibodies evoked by the vaccine are less effective against the Gamma (P1) variant, stated two different studies published in The Lancet.

The first study, conducted by researchers in Brazil, noted that antibodies from nearly all of the individuals who were partially or fully vaccinated with CoronaVac had no detectable impact on the P1 variant. The P1 variant was still found to be sensitive to the antibodies in the plasma of the individuals who had received two doses during the immunization program, but to a lesser extent compared to the B lineage virus. The study is published in The Lancet Microbe.

Interim data from a phase 3 trial revealed that two doses of CoronaVac vaccine offer 83.5% protection against symptomatic COVID-19, and can protect against severe disease and death. So, it appears that neutralizing antibodies may not be the only factor, and that T-cell response also plays a key role in reducing disease severity. The phase 3 trial data is published in The Lancet… (ET Healthworld – IANS, July 9, 2021)