In the United States, the vaccine is authorized in two doses administered 21 days apart. To protect against Covid-19, the first dose prepares the immune system and the second stimulates it.
The researchers found that in those who had a previous natural infection, vaccination increased their antibody levels by more than 140 times. “This increase appears to be at least an order of magnitude greater than that reported after a conventional first-booster vaccine strategy in previously uninfected individuals,” wrote the researchers in their article.
The workers provided blood samples at the time of receiving the first dose and 21 to 25 days after vaccination. The researchers found that people with previous coronavirus infection appeared to generate stronger immune responses to a dose of the vaccine compared to those who had not been previously infected.
“What this data shows is exactly what you would expect – that people who have been naturally infected, who have already developed an immune response to this virus, when they receive the first dose, without quotes, have a reinforcing response,” Offit said. “In other words, they are acting as if they are receiving the second dose.”
But for now, Offit emphasized that people who have already recovered from Covid-19 should receive both doses of the vaccine when it is their turn.
“You could reasonably ask, ‘Well, given that there is a shortage of vaccines, why not make this recommendation that anyone who has already been infected can reasonably receive a dose, period?’ I think the reason that didn’t happen was largely programmatic, “said Offit.
“If you tried to override the current strategy of vaccinating people – that there was a prior screening test to see who was previously exposed and who was not – it would make it much more difficult to launch this vaccine. So people thought, look, give everyone the vaccine, “said Offit.” There is no disadvantage. From worst to worst, you will only get booster responses when you are vaccinated, if you have already been infected naturally. “
Offit added: “If you’ve never been infected with this virus before, the second dose of mRNA vaccine dramatically boosts T cell immunity, dramatically boosts the antibody response, and will undoubtedly give you more complete and lasting protection.”
It is possible that a single dose of the coronavirus vaccine will be sufficient to protect people who have recovered from a Covid-19 attack, said Dr. Francis Collins, director of the US National Institute of Health, on Thursday.
“It seems that in these individuals, a single dose is basically a booster for them because they already had the infection. They already have some antibodies that may be sufficient and may not need the second dose,” Collins told CNN Chief Correspondent Dr. Sanjay Gupta.
Collins said the NIH is “trying to collect as much data about it as possible now”.
But, he said, a single-dose strategy for everyone could result in unforeseen consequences.
“Are these people between first and second place easy targets to be infected?” Collins asked. “Is this really a way to encourage more mutations to occur because they are only partially protected? The virus has a chance to live a little longer in your system and pick up some changes.”
Collins said that until the data shows otherwise, the two doses allowed three to four weeks apart is the regimen that should be followed.
CNN’s Nadia Kounang contributed to this report.