Single-dose of Covaxin to COVID survivor equivalent to 2 doses for non-infected: ICMR study
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New Delhi: Indian Council of Medical Research's latest study finds that a single dose of Covaxin provides a similar immunity response in previously Covid-infected people as those without previous history of Covid infection with two doses of vaccine.
A pilot study was undertaken to examine SARS-CoV-2 specific antibody responses after day 0 (baseline before vaccination), day 28A2 days post-first dose (month 1) and day 56A2 days post-first dose (month 2) of BBV152 in a group of healthcare professionals as well as frontline workers and the antibody responses of individuals with confirmed pre-vaccination SARS-CoV-2 infection were compared with those individuals without prior evidence of infection.
The blood specimens were collected from healthcare professionals and frontline workers who received the BBV152 vaccine at vaccination centres in Chennai, India, from February to May 2021. Blood samples were collected before receiving the first dose of BBV152 too.
Prior infection with SARS-CoV-2 was determined by SARS-CoV-2 IgG positivity at baseline. Antibody levels were measured at three time points: on the day of vaccination (baseline), at month one following the first dose and at month two following the first dose.
The results were determined via a calibration curve, which is an instrument specifically generated by two-point calibration and a master curve provided via the reagent QR code.
Almost all participants with prior Covid-19 infection except two had detectable antibodies at the time of vaccination.
This study, which was approved by the Ethics Committee of ICMR-NIRT offers evidence in support of public health-oriented and immunologically sustained vaccine strategies.
"This is a pilot study. If such findings are confirmed in large population studies, a single dose of BBV152 vaccine may be recommended to previously confirmed Covid patients so that the naA-ve individuals could attain the larger benefit of a limited vaccine supply" said Lokesh Sharma, Scientist and Media Coordinator, ICMR.