The Centre’s idea of single-dose vaccination comes at a time when the UK has decided to reduce the dosage interval of the AstraZeneca vaccine to eight weeks to ensure full protection of its vulnerable population.
CITY EXPRESS NEWS
New Delhi June,1,2021: At a time the shortage of Covid shots in India has slowed down vaccinations, the central government’s new strategy is to test mixing two vaccines together and also the effectiveness of a single dose of Covishield.
“India may soon start in few weeks testing feasibility of a regimen that mixes two different doses of Covid vaccines to see if it helps boost immune response to virus,” said Dr N K Arora, chairman of Covid-19 working group under National Technical Advisory Group on Immunisation (NTAGI).
Meanwhile, Banaras Hindu University researchers have claimed a single dose of vaccine is enough for Covid recovered patients. “We studied the effect of vaccine on Covid recovered and non-infected people. Antibodies in recovered people developed in first week,” Prof Zoology Dept BHU Gyaneshwer Chaubey said.
“While 90 per cent of non-infected people developed antibodies after 3-4 weeks, recovered people developed antibodies after first dose. By giving single-dose to recovered people, we can overcome vaccine shortage. We’ve also written a letter to PM in this regard,” the professor said.
But the reason behind this thought is lost on health experts and epidemiologists. “No, not a good idea at all. There is no data to suggest one dose has proven efficacy to offer sufficient protection against mortality/serious illness at the population level,” said Professor Giridhar Babu, Epidemiologist, Public Health Foundation of India and advisor to the Covid task force state of Karnataka.
“Available evidence suggests that two doses of vaccines are effective in preventing deaths. No efficacy gets proved by looking at the antibody levels that too at the individual levels, they are only at the population level. With respect to one dose, no trial has given any evidence that it will be sufficient in preventing deaths or serious illness. We need to cover both doses especially for the vulnerable population. In the given time frame if we are unable to cover two doses, maybe we can cover one dose, but the second dose needs to be given sometime later at least in the 12 week period when the efficacy is around 84 per cent,” said Dr Babu.
Dr Aviral Vatsa of the NHS, Scotland said, “This is scientifically wrong. Period. In fact, single dose gives some degree of protection only, and the second dose actually makes the protection levels above 60-70 per cent and even more in certain cases. Lack of vaccine doses should be dealt with differently.”
C S Pramesh, Director, Tata Memorial Hospital, said there is no data to suggest that one dose of Covishield is good enough to protect from Covid-19.
The idea of single-dose vaccination comes at a time when the UK has decided to reduce the dosing interval of the AstraZeneca vaccine to eight weeks to ensure the full protection of its vulnerable population. India has done the reverse by deciding to increase the dosing interval for Covishield to 12 weeks, citing evidence from the UK.
Recently, as the UK looks forward to an unlock in June, a study presented to the government emphasised that two doses provided better protection against specific variants of the virus than a single dose.
Covishield is the Indian version of the AstraZeneca-Oxford University vaccine produced by Pune-based Serum Institute of India and is the most used vaccine in India currently. Covaxin manufactured by Hyderabad-based Bharat Biotech is the second most used vaccine.