Amid a heated debate on the required gap between the two jabs of Serum Institute of India’s Covishield vaccine, research conducted in India revealed that a single shot of Covishield has effectiveness up to 61% against the Delta strain, the Indian variant of Covid-19 virus.
Below are the 10 facts you must know about the Covishield vaccine dosage gap:
1. As per Dr NK Arora, Covid Working Group chief, the national Covid immunisation programme began with an interval of four weeks, data indicated an outstanding response. The UK had already increased the gap to 12 weeks by that time.
2. The World Health Organisation (WHO), six weeks later, also suggested that 6-8 weeks interval may be effective. However, the working group decided to look at the real-life data coming in from the United Kingdom.
3. Public Health England in April suggested that a 12-week interval may vary the vaccine efficacy between 65% and 80%. A couple of days later, it decided that with the first Covishield dose, the prevention was 33%, noted the Working Group chairperson. But the number of people in the trial who received that shot was minimal.
4. The Health Ministry of India, on May 13, announced to change the gap from 6-8 weeks to 12-16 weeks. This decision came when supplies of the shot were unable to meet the requirements of people, and infections were mounting across the county.
5. That was the second time in three months that the gap was broadened, triggering speculation to compensate for an acute shortage in production.
6. Meanwhile, the results by the UK were not satisfying. Statistically significant data from Christan Medical College Vellore’s research later, based on a sample size of several thousand when the Delta variant outbreak was at its peak, pointed out that the first dose had a 61% vaccine effectiveness which increased to 65% with two.
7. The only way of protecting from severe disease became hospitalisation in the short run, but a vaccine shot or both Covishield or Covaxin could prevent that.
8. Dr NK Arora’s clarification followed by a Reuters report indicated that the centre had doubled the gap between the two doses of Covishield without approval from the National Technical Advisory Group on Immunisation (NTAGI).
9. Quoting three scientists, including the former chief of the government-run National Institute of Epidemiology, from the Reuters report, they had only discussed increasing the interval to 8-12 weeks, not 12-16 weeks.
10. Dr Harsh Vardhan, Union Health Minister, said the decision to widen the gap was taken transparently based on scientific data.