The ideal gap between two doses of Covishield is two months and another dose of the vaccine should be taken after six months, the Serum Institute of India (SII) chairman Cyrus Poonawalla said here on Friday.

Asked about a report in the medical journal Lancet that antibodies against coronavirus created by Covishield, the vaccine manufactured by the SII, decrease after some time, Poonawalla told reporters that it was true that the antibodies decrease, but "memory cells" remain.