In the United States, the vaccine is given as two doses that are taken 21 days apart. To protect against Covid-19, the immune system boosts the first dose, and the second boosts it.
The researchers found that vaccinations increased their resistance levels more than 140 times in those who had a previous natural infection. “This increase appears to be at least one order of magnitude greater than that reported after a conventional first-boost vaccine strategy in previously uninfected individuals,” the researchers wrote in their paper.
The workers gave blood samples upon receipt of their first dose and thereafter 21 to 25 days after vaccination. The researchers found that people with previous coronavirus infection appeared to generate stronger immune responses to one dose of vaccine compared to those who had not been infected before.
“What these data show is exactly what you would expect – that people who are naturally infected, who have already developed an immune response to this virus, if they then receive the first dose with a quote, have an enhancer reaction,” Offit said. “In other words, they act as if they are getting the second dose.”
But for now, Offit stressed that people who have previously recovered from Covid-19 are advised to still get both doses of vaccine when it’s their turn.
“You can reasonably ask, ‘Well, since there is a shortage of vaccine, why not make this recommendation that someone who has been infected before can get quite a single dose?’ “I think the reason it didn’t happen was largely programmatic,” Offit said.
‘If you were trying to cover up the current strategy of getting people vaccinated – that there was a screening test beforehand to see who had been exposed before and who had not – then it would make the vaccination much more difficult. So people just thought, look, give everyone the vaccine, ‘Offit said. “There’s no downside. The worst case scenario is that you will only get reactions when you are vaccinated if you are already naturally infected.”
Offit added: “If you have never been infected with this virus before, the second dose of mRNA vaccine will dramatically increase your T cell immunity, dramatically increase your antibody response, and it will undoubtedly be more complete and longer protected.”
It is possible that a single dose of coronavirus vaccine may be enough to protect people who have recovered from an attack on Covid-19, said Dr. Francis Collins, director of the U.S. National Institutes of Health, said Thursday.
“It does seem that a single dose in those individuals is a stimulus for them, because they have already had the infection. They already have some antibodies that may be sufficient and they may not need the second dose,” Collins told CNN chief. Medical correspondent dr. Sanjay Gupta.
Collins said the NIH “is currently trying to gather as much data about it as possible.”
But he said a single-dose strategy could have unintended consequences for everyone.
“Are the people who sit between first and second place ducklings to get infected?” Ask Collins. “Is this actually a way we can encourage more mutations to happen because they are only partially protected? The virus has the chance to live a little longer in their system and make some changes.”
Collins said that until the data show otherwise, the two doses allowed three to four weeks apart are the regimen to be followed.
CNN’s Nadia Kounang contributed to this report.