The gap between two doses of the Covid-19 vaccines has been a question of crucial importance amid the pandemic. Health authorities and governments have explored optimum spacing between doses as much to ensure that it provides the best immunity as for enabling the greatest possible number of people to get at least one jab of a vaccine. The gap between doses in India is of 8-12 weeks for the Covishield vaccine, but the Kerala High Court has now asked the Centre to allow paying customers to opt for a reduced interval between doses.
What Has Kerala HC Said?
Hearing a petition filed by garment-maker Kitex, the Kerala HC ordered the Centre to introduce tweaks to the CoWin platform for booking vaccination slots so that paying customers can opt for a gap lower than the 12 weeks now prescribed for the Covishield dose. The HC’s decision was based on the principle of preventing discrimination and it did not recommend the same facility for people opting for free jabs.
Kitex told the court that it had procured vaccines for its employees afterpaying out of its own pocket, but was not being able to give the second shot as the government stipulation was for an 84-day wait. However, it sought a relaxation in that rule citing concessions made for special categories of people like students, athletes and government servants, who have been allowed to get their second dose at a reduced interval.
“The fact that the vaccination is voluntary and there is no compulsion on anyone to accept the same is declared by the Government of India… If that be so, the requirement to administer two doses of the vaccine and the time interval between the two doses for better protection from infection can only be considered as advisory," said the single-judge order, adding that people should be allowed to choose between early and better protection from vaccination.
How Has The View On Gap Between Doses Evolved?
In response to the plea by Kitex, the Centre told the court that the gap between gaps was determined on the basis of scientific evidence and the “technical opinion" is that “the duration of 84 days between 1st and 2nd doses of Covishield is providing the best protection against Covid-19".
However, it did admit that the gap was reduced for certain groups of individuals, but said the decision in that regard was shaped by the “evidence available", which shoed that “the immunity provided by two doses of the Covishield vaccine with intervals less than 12-16 weeks would be better than partial vaccination".
Ever since the first vaccines were rolled out and countries launched their vaccination drives, a debate has continued over the interval between doses. That is because extending the gap represents a departure from the protocol adopted during trials, which mostly had a smaller interval between doses. It was only following real-world use of vaccine and studies post rollout that researchers suggested that increasing the gap actually improves the efficacy of vaccines.
“Because of the urgent need for a Covid-19 vaccine, initial clinical trials of vaccine candidates were performed with the shortest possible duration between doses. Therefore an interval of 21–28 days between doses is recommended by WHO. Depending on the vaccine, the interval may be extended for up to 42 days — or even up to 12 weeks for some vaccines — on the basis of current evidence," says the World Health Organisation (WHO).
What Are Some Of The Vaccines That Have Seen Extended Gaps?
The European Commission (EC) notes that it was in the UK that officials “unexpectedly endorsed stretching the gap between the first and second vaccine dose by up to three months" right after the country had launched its vaccine drive.
“The rationale is that, with the virus raging alongside uncertainty about vaccine supply, vaccinating a greater number of people with a single dose would be more effective at preventing deaths and hospitalisations than if a smaller number of people received two doses," EC said.
But health authorities in UK — which had started its vaccination campaign with the two-dose Pfizer-BioNTech mRNA and the Oxford-AstraZeneca viral vector shots — also cited data from studies that suggested that a wider gap between doses helped. “Data… demonstrate that while efficacy is optimised when a second dose is administered, both offer considerable protection after a single dose, at least in the short term," UK officials had said in December last year. Thus, the country said that the second dose of the Pfizer-BioNTech vaccine could be given between 3 to 12 weeks following the first dose while that of the Oxford-AstraZeneca vaccine could be administered at a 4-to-12 week interval.
However, the US, which had the Pfizer-BioNTech and another mRNA vaccine — made by Moderna — as its vaccination mainstays, did not reduce the gap between doses, preferring to jab people with their second dose after 21 and 28 days, respectively, for the two shots.
But as the UK managed to accelerate its vaccination campaign and reported coverage with at least one dose for most of its eligible population, the country allowed the gap between two doses to be reduced to eight weeks. UK health authorities cited trial done with the Pfizer-BioNTech shot that showed that a gap of eight weeks was the “sweet spot" for vaccinations.
While the Pfizer-BioNTech study showed that “both short and long dosing intervals of the Pfizer vaccine generated strong immune responses overall", UK vaccines minister Nadhim Zahawi said, “As we raced to offer a vaccine to all adults, we took the… advice to shorten the dosing interval from 12 to eight weeks, to help protect more people against the Delta variant".
What Has Been The Gap Scene In India?
When India decided to expand the gap between doses for Covishield in May this year, reports said that health authorities had based the decision on efficacy data from the UK. But after UK moved to reduce the gap, Indian officials said there were no plans to follow suit immediately on the decision.
But amid the need for certain groups of individuals for travelling abroad, the Centre decided to allow a reduction in the dose gap, saying it had to be a minimum of 28 days and that the second dose should be taken before 84 days. The reduction in the gap was only for the Covishield vaccine and not for Covaxin, the indigenous vaccine for which the second dose is spaced at 4-6 weeks after the first.
What About Booster Doses?
Waning antibodies remains a fear when it comes to Covid-19 given the rapid rise of new variants, which is why many countries are now rolling out booster shots against the novel coronavirus. Israel is already giving a third shot to vulnerable groups while the US, too, is said to be mulling a rollout of a third dose.
Closer home, reports last month said that the chairman of the Serum Institute of India — which is making the Oxford-AstraZeneca vaccine under the Covishield label in India — has revealed that employees of the company had been given a third dose of the vaccine.
“After six months, the antibodies go down and that is why I have taken the third dose. We have given the third dose to our 7,000-8,000 SII employees. For those who have completed the second dose, it is my request to take a booster dose (third dose) after six months,” Cyrus Poonawalla was quoted as saying by news agency PTI.