Some scientists have called on governments to administer single doses of Covid-19 after preliminary research suggested they appear to offer a degree of protection, despite manufacturers recommending two doses. But other scientists warn that a single inoculation is not enough to confer lasting immunity.
Food and Drug Administration (FDA) tests of Moderna and Pfizer vaccines found that a single dose of any of them seemed to provide some protection against coronavirus.
The effectiveness of a Modern vaccine dose was about 80-90 percent, the researchers found in studies in Stage 3 before its approval by the US regulator in January.
The scientists found that the Pfizer-BioNTech test is 70% effective at a single dose, compared to 95% at two.
Following the approval of the Oxford-AstraZeneca vaccine, British regulators said it was around 70% effective within 12 weeks of the first dose.
Given that vaccine stocks are limited around the globe, such findings raise a key question for governments and healthcare professionals: does it make more sense to vaccinate fewer people with both doses for maximum protection or is it better to spread them? vaccinations, inoculating more widely but less completely?
Some have suggested that governments should aim to give as many people as possible a single dose, instead of using half of the vaccines currently available for the second dose.
The modern “was not shy to show that a single dose was so effective and I do the calculations correctly,” Chris Gill, an infectious disease specialist at Boston University, told WBUR, a Boston NPR affiliate.
Consequently, governments should deliver as many single doses as possible as soon as possible, Gill argued: “We could save a lot of lives. We can give people two doses now, but in the meantime a lot of people who could have gotten the vaccine will die. Isn’t this an example of where, again, the perfect is the enemy of good? “
In Britain, where a new, more contagious coronavirus strain is accelerating transmission, former Prime Minister Tony Blair wrote an opinion piece in The Independent on December 22, arguing that the British government should use “all doses available in January as the first doses, that is, do not hold back half for the second dose ”in the expectation that“ even the first dose will provide substantial immunity ”.
But others warn that more research needs to be done and that by then it makes more sense to administer the vaccines in two separate doses as designed.
“If the second dose of vaccine was useless and I knew [it] it did not extend the duration of protection, the principle would be to protect as many people as possible and save as many lives as possible, “Barry Bloom, an epidemiologist at Harvard University, told WBUR.
Pfizer scientists warned in a statement on Thursday not to be too confident that a dose would provide sufficient long-term protection.
“There is no data” to show that protection after the first dose is sustained after 21 days, they wrote.
Taking a second dose is important because it increases the chances of restoring life to normal, giving people lasting immunity, suggested Jean-Daniel Lelièvre, head of the immunity and infectious diseases department at Henri-Mondor de Créteil Hospital near Paris. “The purpose of a second dose is to make the immunity last, and as things stand, 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 give two more doses according to the recommendations, the Minister of Health, Olivier Véran, told France Info on Saturday. France will follow the manufacturers’ guidelines for administering the Pfizer-BioNTech vaccine, which was approved by France’s national regulatory authority on 24 December. Inoculations began three days later.
“No data” to support UK mix-and-match jabs
Along the Channel, the British government changed its vaccination guidelines on December 30 to allow the administration of the second dose of both Pfizer-BioNTech and Oxford-AstraZeneca jars up to 12 weeks after the first, in instead of three weeks, as originally planned.
The UK government also said in guidelines published on December 31 that, in rare cases, people could be given a mixture of two Covid-19 vaccines – despite the lack of evidence on the degree of immunity provided by the doses of mixing.
Both vaccines are intended to be given as two shots, given a few weeks apart, but were not designed to be mixed.
However, the British health authorities said that if “the same vaccine is not available or if the first product received is not known, it is reasonable to offer a dose of the product available locally to complete the program”.
Mary Ramsay, head of immunization at Public Health England, said that this would only happen in very rare cases and that the government did not recommend mixing vaccines.
“Every effort should be made to administer the same vaccine, but where this is not possible, it is better to administer the second dose of another vaccine than not at all,” she told Reuters.
Some have warned that the new guidelines in the UK could have been born out of desperation.
“There’s no data on this idea,” John Moore, a vaccine expert at Cornell University, told the New York Times.
Health officials in the UK “seem to have completely abandoned science now and are just trying to figure out how to get out of the mess,” Moore said.
(FRANCE 24 with REUTERS)