Chairman of India’s COVID-19 Working Group of the National Technical Advisory Group on Immunisation (NTAGI), Dr. N. K. Arora has said that the decision to increase gap between Covishield doses is based on scientific evidence. In an interview with DD News, Dr. Arora informed that none of the NTAGI members dissented regarding the decision. He explained that the decision to increase the gap between two Covishield doses from four to six weeks to 12 to 16 weeks lay in the fundamental scientific reason regarding behaviour of adenovector vaccines.
The NTAGI Chairman said that in the last week of April this year, United Kingdom’s Public Health England released data which showed that vaccine efficacy varied between 65 to 88 per cent when dosage interval is 12 weeks. He said, based on this scientific evidence which showed increased efficacy of adenovector vaccines with increased dosage duration, the decision was taken on 13th of May in the country to increase the gap between two doses of Covishield vaccine. Dr Arora said that the earlier decision of four weeks was based upon the bridging trial data available during the initial phase. He informed that other countries like Canada and Sri Lanka including others are also using 12 to 16 weeks interval for AstraZeneca vaccine which is the same as Covishield vaccine.
Responding to question over any proposal to reduce Covishield dosage gap in near future, Dr. Arora said that the decision will be taken scientifically, giving paramount importance to the health and protection of the community. He added that COVID-19 and its vaccination is still in a very dynamic phase and in case the vaccination data favours narrowing down the gap, the Committee will take the decision on the basis of merit and its wisdom.