Covishield efficacy higher if gap over 28 days, says India’s Serum Institute

According to a top scientist at Serum Institute of India (SII), efficacy of the Covishield vaccine goes up if the gap between two doses is more than 28 days.

Serum's Covishield and Bharat Biotech's Covaxin -  both the vaccines are being used in India; and each are two dose shots with a prescribed gap of 28 days between the jabs, reports thje NDTV.

Suresh Jadhav, executive director, SII, said results were much better when this gap was increased by a few weeks.

"Even if the difference is of four weeks, it gives good protection, but around 70-80 per cent. If the gap is increased further up to six weeks or eight weeks or 10 weeks, the results are much higher," Dr Jadhav said. 

He explained that the clinical trial was conducted in phase 3 with a 28-day gap, so that became the standard.

But if the second dose was taken faster, it would certainly guarantee 70 per cent protection to the receiver, Dr Jadhav said.

"But if you want protection for a longer period and a higher level, it is better to take it after six to eight weeks," he added.

Dr Jadhav also explained that getting a second dose was definitely advisable after the first shot as it gave substantial protection.

To the common question of whether vaccination is necessary for those who have recovered from the coronavirus, he said: "Even after Covid 19, people should get vaccinated. This is because it has been seen that people can get Covid twice."

He also said two vaccines must not be mixed up, tackling another most-asked question.

"Each dose will be from a different vaccine, and the technology is different, so one should not take both vaccines," he asserted.