India on Sunday reached the milestone of administering 200 crore Covid-19 vaccine shots in the past one and half years after making a slow start in January 2021.
The world’s largest adult vaccination programme began on a low scale initially covering only healthcare workers and front line workers, but expanded slowly to include senior citizens and subsequently all adults over 18 years.
With schools opening after two years, the campaign was later extended to incorporate school going children above 12 years.
"India has created history again. Congratulations to all Indians on crossing the special figure of 200 crore vaccine doses. This has strengthened the global fight against Covid-19,” Prime Minister Narendra Modi tweeted.
Covishield manufactured by Serum Institute of India using the AstraZeneca-Oxford University technology was the most used vaccine as over 159 crore doses of it was used in the campaign.
Homegrown Covaxin became a poor second with just about 32 crore doses. Three other vaccines were used in small numbers in the later stage of the programme.
“The Indian people too need appreciation for not falling prey to anti-vaccine propaganda. Together, we have set a global gold standard,” said K Srinath Reddy, president, Public Health Foundation of India.
While close to 90 per cent adults and a large number of school going children are now fully vaccinated, the uptake of booster shots has started rising in the last two days after the Centre made it free for anyone above 18 years for 75 days.
The number of booster shots for 18-59 year olds crossed the one crore for the first time even though it was kept open for all since April. However, it was a paid service available at private centres for this age group while those over 60 would get it free in government centres.
The increase in the booster dose coverage coincides with a new study that shows recipients of Covishield vaccine would be requiring a booster shot just after five months to minimise the risk of a Covid-19 breakthrough infection. India used more than 159 crore doses of Covishield shots.
Published in the Proceedings of the National Academy of Sciences, the study shows that as a consequence of waning immunity, those fully vaccinated with Covishield should receive a booster within five months.
"We definitely want to boost before most people get reinfected. This turns out to be about 5 months for J&J and AstraZeneca vaccines (same as Covishield) and around 10 months for mRNA vaccines," Jeffrey Townsend from Yale School of Public Health, who led the study, told DH.
The time schedule has been calculated considering a 5 per cent chance of reinfection. “I would point out that a 1 per cent chance would be even better, and call for an even quicker boost post-vaccination,” he said.
Asked how long Covaxin can protect, Townsend said though it was not part of the study, he would expect the Bharat Biotech product to provide a durability of immunity at least equivalent to AstraZeneca and J&J vaccines.