By last month, a clear pattern in the data “popped out at us,” said research leader Susan Cheng. Those who had recovered from Covid-19 responded to their first shot so robustly that the results rivaled never-infected colleagues who had received both shots. The implication was clear. If you’ve had Covid, you may only need one of the two doses recommended by and .
“We did not expect that this was going to jump out like a smoking gun,” said Cheng, who co-authored . In fact, if you already had the virus, your immune response after one vaccine is likely to be even better than a never-infected person’s after two, according to just out in the New England Journal of Medicine.
The issue of giving only a single dose to people who have had Covid has become all the more urgent since safety concerns have been raised about Johnson & Johnson’s and ’s vaccines. The implications at a time of strained global supply are striking: giving previously infected people just one mRNA vaccine shot could free up more than 110 million doses worldwide, according to a by immunologist Mohammad Sajadi and colleagues.
In Israel, a world leader on coronavirus vaccinations, health authorities initially withheld vaccines altogether from recovered Covid patients, but in February recommended they receive one shot. suggests that the booster vaccine adds protection against newer variants that originated in the U.K., South Africa and Brazil.
In the U.S., the Centers for Disease Control and Prevention still recommends two vaccine doses for people who have had Covid, but the mounting evidence that one vaccine could be enough is under discussion. The U.S. has administered enough doses for 31% of its population, while Israel has given enough for 57%, according to the Bloomberg Vaccine .