Two doses of the Covishield vaccine have produced more antibodies than two doses of Covaxin, according to a real-world study on coronavirus vaccinations in healthcare workers in India, The Hindu reported on Sunday. The study is yet to be peer reviewed but was shared on medRxiv, an online portal for unpublished reports on medical sciences.

As many as 515 healthcare workers from 22 cities were surveyed between January and May. Of 515 participants, 90 received Covaxin shots. Only 6% tested positive after receiving either one or both shots of the Covishield or Covaxin vaccines.

“Both vaccines elicited good immune response after two doses, although seropositivity rates and median anti-spike antibody titre was significantly higher in Covishield, compared to Covaxin arm,” the study said.

“Among 515 healthcare workers (305 male, 210 female), 95 per cent showed seropositivity [higher antibodies] after two doses of both vaccines,” the study said. “Of the 425 Covishield and 90 Covaxin recipients, 98.1 per cent and 80 per cent, respectively, showed seropositivity.”

One dose of Covishield produced 10 times more antibodies than Covaxin, it added. After a second dose was added, it was found that two shots of Covishield produced about six times more antibodies than Covaxin.

However, the study added that there were fewer “breakthrough infections” after the Covaxin shots. Breakthrough infections are those where a patient tests positive for the coronavirus two weeks after receiving the second shot of the vaccine.

As many as 27 participants who received both shots of a vaccine tested positive. Of these, two cases were moderate while the remaining only had mild infections. As many as 5.5% recipients of Covishield reported breakthrough infections, while that number went down to 2.2% for Covaxin, the study said.

There was no co-relation between the participant’s gender, body mass index, blood group and comorbidities and their response to the vaccines, those with type 2 diabetes and those over 60 years old had fewer antibodies, the study showed, according to India Today.

India has so far approved the AstraZeneca-Oxford vaccine manufactured by Serum Institute of India, Covishield, Bharat Biotech’s Covaxin and Russia’s Sputnik V. The Russian vaccine was only approved in April and has not yet been widely used.

India on Monday registered 1,00,636 new coronavirus cases, pushing the total infection tally in the country to 2,89,09,975 since the pandemic broke out in January last year. With 2,427 deaths, the toll rose to 3,49,186. There are 14,01,609 active cases and 2,71,59,180 patients have recovered so far from the infection.