There has been a significant drop in Covid antibodies within four months after complete vaccination, a new study conducted by the Indian Council of Medical Research (ICMR) revealed.
The study was conducted at ICMR's Regional Medical Research Centre in Bhubaneswar on 614 fully vaccinated health workers during India's deadly delta variant surge. In this study, 308 participants were administered two doses of the Covishield vaccine and 306 were given two doses of Covaxin.
Out of the total 614 workers, 81 contracted Covid-19 infection for the first time. Among the 257 participants having a Covid history, 33 got reinfection even after being jabbed with both doses of vaccine, India Today reported.
Antibody Levels Decrease Over Time For Both Covaxin And Covishield
For those who had got a Covaxin shot, their antibody level started to drop significantly and antibodies for the ones administered with Covishield started to weaken after six months from the first dose.
"In Covaxin, antibodies started decreasing in the second month after inoculation. In Covishield, antibodies witnessed a decrease after the fourth month of vaccination," said Dr Bhattacharya, one of the authors of the study.
"We report a significant decline of antibody post two months and four months among Covaxin and Covishield recipients after two doses of these vaccines," she added. She, however, added that weak antibodies do not indicate that a person is not protected at all.
"T cells and B cells also contribute in creating a memory to fight the Covid-19 infection," Dr Sanghamitra Pati, co-author of the study said.
"A follow-up of this study will be done for a year. These were healthcare workers and more pan India studies are needed for further conclusion," Dr Pati added.
Meanwhile, a study in the UK on more than a million people showed reduced antibodies, even after being inoculated with two doses of either the Pfizer or AstraZeneca vaccine. In the US also, studies suggested vaccine protection weakened among the older generation. Moderna vaccine also showed waning of immunity.