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 gap — almost 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 the doses of the vaccine results in a higher vaccine efficacy rather than a six-week interval.
The first dose of the vaccine offers 76% protection for up to three months, said the study. Many doctors in India, too, had raised the “better antibody levels with longer gap” theory with the government.
We believe a gap of two months should be provided between the two shots,” said Dr Shashank Joshi, who is a member of the Maharashtra Covid task force. The other important message of the new Lancet study is that a longer gap would allow countries to vaccinate a larger proportion of their population more rapidly.
In a statement, the study’s lead author Andrew Pollard from the University of Oxford said, “Where there is a limited supply, policies of initially vaccinating more people with a single dose may provide greater immediate population protection than vaccinating half the number of people with two doses.”
The team also found that a single dose of vaccine is highly efficacious in the first three months (76% efficacy from 22 days after vaccination onwards). “Antibody levels against the SARS-CoV-2 spike protein remained at similar levels for 3 months,” said the Lancet study.