Some researchers have urged governments to release single doses of Covid-19 after preliminary research suggested that they appear to provide some protection, despite manufacturers recommending two doses. But other researchers warn that a vaccination is not enough to provide lasting immunity.
Food and Drug Administration (FDA) analyzes of both Modern and Pfizer vaccines found that a single dose of either appears to provide some protection against coronavirus.
The effect of a dose of Moderna vaccine was about 80 to 90 percent, researchers found in stage 3 trials before it was approved by the US regulator in January.
Researchers found that the Pfizer-BioNTech jab is 70 percent effective with one dose compared to 95 percent effective with two.
After approving the Oxford-AstraZeneca vaccine, British regulators said it was about 70 percent effective during the 12 weeks after the first dose.
With vaccine deliveries limited worldwide, such results raise a key issue for governments and healthcare professionals: Is it more meaningful to vaccinate fewer people with both doses for maximum protection or is it better to spread vaccinations, inoculate more widely but less completely?
Some have suggested that governments should strive to give as many people as possible a single dose, instead of using half of the vaccines currently available in other doses.
Modern was “not shy about showing that a single dose was so effective, and they do the math right,” said Chris Gill, an infectious specialist at Boston University, WBUR, Boston’s NPR subsidiary.
Consequently, governments should issue as many single doses as possible as soon as possible, Gill argued: “We can save many lives. We can give two doses to humans now, but in the meantime, a bunch of people who could have gotten the vaccine will die. Is this not an example of where, once again, the perfect is the enemy of the good? ”
In the UK, where a new, more contagious coronavirus strain is accelerating transmission, former Prime Minister Tony Blair wrote a statement in The Independent on December 22, arguing that the British government would use “all available doses in January as first doses, that is not to hold back half for other doses “in the expectation that” even the first dose will provide significant immunity “.
But others warn that more research needs to be done, and that until then it makes more sense to administer the vaccines in two separate doses according to plan.
“If the second vaccine dose was superfluous, and we knew [it] did not extend the duration of the protection, the principle would be to protect as many people and save as many lives as possible, says Barry Bloom, an epidemiologist at Harvard University, to WBUR.
Pfizer researchers warned in a statement on Thursday not to be too sure that a dose would provide enough protection in the long run.
There is “no data” showing that protection after the first dose is maintained after 21 days, they wrote.
Administering a second dose is important because it increases the chances of getting life back to normal by giving people lasting immunity, suggested Jean-Daniel Lelièvre, head of the Department of Immunity and Infectious Diseases at Henri-Mondor de Créteil Hospital near Paris. “The purpose of a second dose is to keep the immunity lasting, and as it stands, there is no evidence that a single dose would provide the same level of protection,” he told the French daily Le Monde.
The French government will still issue two doses as recommended, Health Minister Olivier Véran told France Info on Saturday. France will follow the manufacturer’s guidelines for the administration of the Pfizer-BioNTech vaccine, which was approved by the French National Regulatory Authority on 24 December. The inoculations began three days later.
‘No data’ to back British mix-and-match jabs
Across the channel, the UK government changed its vaccine guidelines on December 30 so that the second dose of both Pfizer-BioNTech and Oxford-AstraZeneca jabs could be administered up to 12 weeks after the first, instead of the three weeks originally planned.
The British government also said in guidelines published on December 31 that people in rare cases could receive a mixture of two Covid-19 vaccines – despite a lack of evidence of the extent of immunity through mixed doses.
Both vaccines are intended to be administered as two shots, several weeks apart, but they were not designed to be mixed.
Nevertheless, UK health authorities said that if “the same vaccine is not available, or if the first product received is unknown, it is reasonable to offer a dose of the locally available product to complete the schedule”.
Mary Ramsay, head of vaccinations at Public Health England, said that this would only happen on extremely rare occasions and that the government did not recommend mixing vaccines.
“Every effort should be made to give them the same vaccine, but where this is not possible, it is better to give a second dose of another vaccine than not at all,” she told Reuters.
Some warned that the new guidelines in Britain could have been born of desperation.
“There is no data on this idea at all,” John Moore, a vaccine expert at Cornell University, told The New York Times.
Health officials in the UK “seem to have abandoned science completely now and are just trying to guess at a mess”, said Moore.
( Jowharwith REUTERS)