Some scientists have asked governments to distribute single doses of Covid-19 after preliminary research has suggested that they appear to provide a degree of protection, despite manufacturers recommending two doses. But other scientists warn that an inoculation is not enough to confer lasting immunity.
Food and Drug Administration (FDA) analyzes of the Moderna and Pfizer vaccines found that a single dose of both appears to provide some protection against the coronavirus.
The effectiveness of a dose of the Modern vaccine was about 80 to 90 percent, the researchers found in stage 3 tests before it was approved by the US regulator in January.
The scientists 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 in the 12 weeks after the first dose.
With limited vaccine supply worldwide, these findings are raising an important question for governments and medical professionals: does it make more sense to vaccinate fewer people with both doses for maximum protection or is it better to spread vaccinations, inoculating more widely but less completely ?
Some suggested that governments should aim to give as many people as possible a single dose, instead of using half of the vaccines currently available in second doses.
Moderna “was not ashamed to show that a single dose was so effective and they do the math,” said Chris Gill, an infectious disease specialist at Boston University, to WBUR, an affiliate of Boston’s NPR.
Consequently, governments should distribute as many single doses as possible as quickly as possible, Gill argued: “We could save many lives. We can give people two doses now, but in the meantime a group of people who could have taken 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 strain of coronavirus is accelerating transmission, former Prime Minister Tony Blair wrote an article in The Independent on December 22 arguing that the British government should use “all doses available in January as first doses, that is, not retain half for the second doses ”, in the expectation that“ even the first dose will provide substantial 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 as planned.
“If the second dose of the vaccine were superfluous, and we 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 overly confident that a dose would offer sufficient protection in the long term.
“There is no data” showing that protection after the first dose is maintained after 21 days, they wrote.
The administration of a second dose is important because it increases the chances of normalizing life by giving people lasting immunity, suggested Jean-Daniel Lelièvre, head of the immunity and infectious diseases department at the Henri-Mondor de Créteil Hospital, near Paris. “The purpose of a second dose is to make 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 newspaper Le Monde.
The French government will still give two doses as recommended, Health Minister Olivier Véran told France Info on Saturday. France will follow manufacturers’ guidelines in administering the Pfizer-BioNTech vaccine, which France’s national regulator approved on December 24. The inoculations started three days later.
‘No data’ for UK mix-and-match jabs
Across the Channel, the British government changed its vaccine guidelines on December 30 to allow the second dose of both Pfizer-BioNTech and Oxford-AstraZeneca jabs to be administered up to 12 weeks after the first, instead of three weeks as originally planned.
The UK government also said in guidelines published on December 31 that, in rare cases, people could receive a combination and combination of two Covid-19 vaccines – despite the lack of evidence on the extent of immunity offered by mixing doses. .
Both vaccines should be administered as two injections, several weeks apart, but they are not designed to be mixed.
Still, British health officials 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 product available locally to complete the schedule”.
Mary Ramsay, head of immunizations 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 must be made to give them the same vaccine, but when that is not possible, it is better to give a second dose of another vaccine than ever,” she told Reuters.
Some have warned that the new UK guidelines may have arisen out of desperation.
“There is no data on this idea,” John Moore, a vaccine expert at Cornell University, told The New York Times.
Health officials in Britain “seem to have completely abandoned science now and are just trying to guess how to get out of the mess,” said Moore.
(FRANCE 24 with REUTERS)