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Former COVID-19 patients may need only one dose of the Pfizer/BioNTech or Moderna vaccine to get the effect of two doses, researchers suggested.

The disease itself may "prime the body" to produce the antibodies seen with the two-dose regimen, according to an exploratory study reported at the virtual that examined titer levels of antibodies in patients who had COVID-19 and those who did not.

Mark Mulligan, MD, director of the Vaccine Center at New York University Langone Health in New York City, said that 6 to 14 days after patients received a vaccine dose, the specific titers associated with infection response were dramatically higher in patients who had previously had COVID-19 than in coronavirus-naive vaccine recipients, with titer levels of 200 versus 27, respectively.

In addition, Mulligan said, the second dose in patients who had COVID-19 didn't measurably increase the titers, whereas it did for previously uninfected patients.

"What I think we have done is hypothesis-generating stuff," Mulligan cautioned. "Our data support the hypothesis that people with a history of COVID might only need one dose of an mRNA COVID-19 vaccine.... We can't make that recommendation, [but] I do think it is something worth paying attention to."

Mulligan said the study wasn't confined just to antibody titers. As well, "the quality of antibody, the B-cells, the ability to neutralize the variants, all of those after one dose in people who are experienced with COVID is very similar to what we see after two doses in people who have not had COVID before," he said.

For the study, the researchers evaluated 32 individuals who received the Pfizer/BioNTech vaccine and one who received the Moderna vaccine, both of which are mRNA-based. Fourteen had recovered from COVID.

The moderator of a virtual press conference that included the study, Sharon Hillier, PhD, of the University of Pittsburgh School of Medicine, told 名媛直播: "I was fascinated with the notion that potentially people who had COVID-19 already had more significant reactions to the vaccine, which meant they were already primed. But this is one vaccine in one setting, and we saw there were questions about other vaccines such as the Sputnik [V] vaccine used in Russia, and we really don't know until we know."

"As a human being who is also a mother of a son who had COVID-19, I bet my son could get one shot of a vaccine and will be fine," Hillier continued. "As a scientist, I am like everybody else -- you would have to figure it out for each vaccine, and before you recommended it as a broader public health strategy, we need a lot more data. But these data were really tantalizing. It is biologically plausible and painted a picture for the kinds of additional data that should be collected."

"I think establishing a registry for the immune response seen in those who already had COVID would help us extend those findings," Hillier added.

Mulligan acknowledged limitations to the study, "including the fact that everyone eventually did get two doses of the vaccine, so we can't compare over time one dose to two doses."

In addition, he said, the patients who had recovered from COVID-19 had been infected in March and April of 2020; they were given the vaccine an average 8.4 months later. The small numbers of patients make it difficult to know if the interval between getting the disease and the vaccine matters.

He told 名媛直播 that the reactions seen to one dose of the vaccine in people who had COVID-19 seemed similar to those who received a second dose of one of the mRNA vaccines. "Some of the reactions to the vaccine may be a little more intense, but all have been within the boundaries of tolerability," he said. "We are still analyzing that."

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