Dikhyaa Mohanty 
COVID antibodies start declining after two months in recipients of Covaxin and after three months in those vaccinated with Covishield as reported in a recent study led by ICMR-Regional Medical Research Centre (RMRC), Bhubaneswar.
According to the reports, the study was conducted in March 2021 and was undertaken to determine the most common antibody IgG (Immunoglobulin G) among fully vaccinated healthcare workers in the state. As to ICMR-RMRC scientists, samples from 614 fully vaccinated healthcare workers were collected for the study. The participants comprised 308 (50.2 per cent) Covishield and 306 (49.8 per cent) Covaxin recipients. Eighty-one participants reported breakthrough cases (COVID infection even after full vaccination).
The report further added that around 257 participants had contracted the infection before being vaccinated and among them, 33 were reinfected after two shots of the vaccine. The samples were collected from Berhampur, Khurda and Burla.
Further, the report added that the production of vaccine-induced IgG antibodies is significantly higher in Covishield compared to Covaxin. In seronegative individuals, the rate of seroconversion after 28 days of the first dose was 81.9 per cent for Covishield and 16.1 per cent for Covaxin. The results of 533 individuals without any history of infection post-vaccination indicated a significant drop in spike RBD IgG concentration for both vaccines.
He, however, was quick to point out that the vaccines are working fine and the severity is much less in such cases. The scientist, however, said that studies are on to know the threshold level of antibodies for protection against COVID.
