A study of Healthcare workers (HCW) in India reported that two doses of Covishield vaccine produces more antibodies than Covaxin doses. This study also said that there were relatively fewer instances of 'breakthrough infections' after the latter.
Although the study is being peer-reviewed and has been submitted to a journal, it appears as a preprint in MedrXiv, which is an online repository.
By a collective of doctors the study shows that none of the participants, who were also all doctors and got both doses of vaccines, were ill. Only about 6% tested positive at different points of the vaccination schedule. While both vaccines were protective, there were differences in the protection accorded by a single dose of the vaccines, says the study.
For the mentioned study, a total of 515 healthcare workers from 13 States and covering 22 cities were evaluated from January to May 2021. Their blood samples were also tested for the presence, quantity of antibodies produced and levels of the specific antibodies that are directed to the spike protein of the virus.
Medical expert in the study says that a single dose of Covishield elicited about 10 times the antibodies than Covaxin whereas a second dose narrowed the gap somewhat, with Covishield-triggered antibodies about six times that of Covaxin-stimulated ones.
"Contrarily, Covishield showed a good seropositivity rate and a 4-fold rise in median antibody titre even after a single dose," wrote the author.
The authors in this research study also evaluated the relationship of immune response to gender which is a history of testing positive for COVID prior to vaccination and co-morbidities.
Accordingly, the 30 HCWs who tested positive for the virus, three tested positive after the first dose and 27 after the second.
Dr A.K. Singh who is a senior medical officer of the GD Hospital and Diabetes Institute, Kolkata and among the authors of the paper, said the greater number of infections after the second wave was probably due to the increased number of cases after April and the high exposure of the study participants — all doctors in COVID hospitals — to patients during the second wave.
