MUMBAI: India has decided to stick to the 28-day gap between two shots of Covidshield vaccine, but there is growing evidence that a longer period – nearly three months – would be better. In a study published in medical journal The Lancet, researchers from Oxford university (where Covishield was developed) said a three-month interval between doses of the vaccine results in a higher vaccine effectiveness instead of a six week interval.
The first dose of the vaccine provides 76% protection for up to three months, the study said. Also, many doctors in India had advanced the theory of “better antibodies with longer gap” with the government.
We believe that there should be a gap of two months between the two shots, ”said Dr. Shashank Joshi, who is a member of the Maharashtra Covid Task Force. The other important message from the new Lancet study is that a wider gap would allow countries to vaccinate more of their populations more quickly.
In a statement, the study’s lead author Andrew Pollard writes of the University of Oxford said, “Where supply is limited, the policy of initially vaccinating more people with a single dose may provide greater immediate population protection than half the number of people vaccinated with two doses.”
The team also found that a single dose of vaccine is very effective in the first three months (76% efficacy from 22 days after vaccination). “Antibody levels against the SARS-CoV-2 spike protein remained at comparable levels for 3 months,” said the Lancet study.