According to people who have had Covid-19, a single dose of Pfizer vaccine is enough to provide robust protection against the coronavirus, according to two new studies from Britain published late Thursday in The Lancet, a prominent medical journal.
The studies, one of the first fully reviewed articles to gauge how to vaccinate people who have had Covid-19, added strong evidence for vaccinating people who already have antibodies to the virus, but with only one dose Pfizer vaccine. .
One of the studies, led by researchers at University College London and the UK on public health, described the benefits of the strategy.
“It could potentially accelerate the deployment of the vaccine,” they said. And it could again prevent dangerous new mutations: ” A broader vaccination-free coverage induced could reduce the emergence of the variety, ” the newspaper said.
In recent weeks, several studies on the subject have been posted online that have not yet been published in scientific journals, showing that one dose of coronavirus vaccine strengthens people’s antibodies from an earlier infection.
People’s immune responses to infection are very variable: most people produce substantial and long-lasting antibodies, while others with milder infections produce relatively little, making it difficult to know how to protect them from the virus.
Vaccines serve as a stimulant for the immune response of humans, causing enough antibodies to provide protection. A single dose, rather than the complete protocol for two doses, is enough for those infected, a number of studies have suggested.
Some researchers in the United States are trying to persuade the Centers for Disease Control and Prevention to recommend giving only one dose to people who have recovered from Covid-19. The studies from Britain are likely to put pressure on health officials there to consider the same approach.
More than 28 million people in the United States and four million people in Britain, along with many others whose diseases have probably never been diagnosed, have been infected so far.
One of the new studies – led by Charlotte Manisty, a professor at University College London, and Ashley D. Otter, a scientist at Public Health England – has identified 51 health workers in London who have been undergoing routine antibody tests since March and subject to infections. . This gave researchers an extraordinarily detailed picture of the existing protection against the virus.
About half of the health workers experienced a mild or asymptomatic infection. And a single dose of the Pfizer vaccine raised their antibody levels more than 140 times higher than their peak levels before being vaccinated, the study said. It appears that they provide better protection against the coronavirus than with two doses of the vaccine in people who have never been infected, the researchers write.
The study raised the idea of giving blood tests in the weeks before they are eligible for a Pfizer vaccine to determine if they already have antibodies. People’s immune responses to an infection are very variable, which can be difficult to predict without a blood test that can be completely protected with a single dose.
As a further benefit of the single-dose strategy, the researchers wrote that it would save people who are already infected from the unpleasant side effects that sometimes occur in a group.
The second study, led by scientists from Imperial College London, measured the immune responses of 72 health workers who were vaccinated at the end of December. A third showed signs that they had been infected before.
For humans, one dose of the Pfizer vaccine stimulated ‘very strong’ antibody responses, the study said, as well as ‘very strong T-cell responses’, citing another arm of the immune system.
It is not clear how long the immune response after vaccination will last in people who have been infected before, compared to those who have not.