Single Covishield dose 61% effective against Delta variant: Covid-19 panel head

Amid debate over the gap between two doses of the Covishield vaccine, NTAGI chief Dr N K Arora said that a single dose of the vaccine is 61 per cent effective against the Delta variant of SARS-CoV-2.

Dr Arora cited a Public Health England study that suggested a 12-week interval showed the efficacy of the vaccine between 65 and 80 per cent, with one dose providing just 33 per cent protection. However, the sample size of the study was very small, Dr Arora said, as per an NDTV report.

India had begun the Covid immunisation programme with an initial interval of 4 weeks, but by then, the UK had already increased the interval to 12 week, Dr Arora said.

Read | Covishield dose interval under discussion: NTAGI working group chairman

Six weeks later, the WHO also suggested that 6-8 weeks interval may be a good idea. The working group, however, decided to look at the real-life data coming in from the UK, Dr Arora said.

Dr Arora and his team was unconvinced with the results of the UK study, but after another study conducted by the Christian Medical College at Vellore, during the peak of the Delta variant outbreak, they saw that the Covishield vaccine had 61 per cent efficacy with one dose, with 2 doses increasing it to 65 per cent, the report said.

Read | Indian scientists say they didn't back doubling of Covid-19 vaccine dose gap

"In the short run, the protection from serious disease, hospitalisation, and death is similar whether one has received one dose or two doses of Covishield and Covaxin," Dr Arora said.

Dr Arora's clarification follows a report that alleged that the duration between Covishield doses was increased without a nod from the NTAGI.