India’s decision to increase the gap between the first and the second dose of the Covishield vaccine to 12-16 weeks from the existing 6-8 weeks may not be out of sync with the recommendations of the UK and WHO. The UK and the WHO recommend gaps of 4-12 weeks and 8-12 weeks, respectively, between the two doses.
Indeed, on April 30, Spain revised its national directive on the vaccine, saying those under 60 years of age who had received the first dose should get their second one only 12-16 weeks after.
Experts of the Oxford Vaccine Group, analysing the results from four trials in the UK, Brazil and South Africa involving 17,178 participants, had noted in an article published in The Lancet that Oxford-AstraZeneca vaccine’s efficacy was 55.1% when the two doses are administered less than six weeks apart and 81.3% when given 12 weeks apart.
The European Union, where the Oxford-AstraZeneca-developed vaccine under the brand-name Vaxzevria, has approved the vaccine with a 4-12 week gap between the first and the second dose. The directive, among other reasons, cited both long duration and high degree of protection from Covid-19 following the first dose and the lower chances of severe Covid-19 morbidity in the younger age groups.
India’s health ministry has accepted the NTAGI’s Covid Working Group’s recommendation to widen the gap between the two doses; the decision comes at a time of an acute shortage of vaccines in the country.