Reinfected Marines also had lower levels of antibodies from their initial bout, compared with Marines who didn’t get reinfected.
“Two-thirds of the 19 Marines who were reinfected didn’t have measurable neutralizing antibodies,” Sealfon noted, suggesting that some people who get infected don’t generate antibodies.
The good news: Having antibodies after infection does protect you against reinfection. The bad news: Even if you’ve had COVID, there remains a risk you’ll get it again.
“That might not cause problems for the patient, and certainly young people — like those in our study — are mostly asymptomatic,” Sealfon said. “But it certainly can mean that there is a risk that they can then transmit a new infection to those who are more vulnerable.”
That means mask-wearing, social distancing and getting vaccinated will still be important, regardless of your prior infection history.
“Vaccination to provide additional protection is still warranted for those who’ve been infected,” Sealfon said. “Because we know that you certainly boost your antibody response with vaccination, even if you already have antibodies.”
But Dr. Sandro Cinti, a professor of infectious disease at Michigan Medicine at the University of Michigan in Ann Arbor, said it’s best not to read too much into these findings.
“These are early results, with a very small number of patients,” he noted. “You have to be very careful interpreting all the COVID studies that are coming out now, many of which have not been peer-reviewed.”
Cinti said a viral infection typically does provide protection from further infection.
“Is there the possibility of reinfection with COVID? Maybe,” he said. “But none of these studies answer that question anywhere near definitively. The only thing definitive is that we just don’t really know.”
The U.S. Centers for Disease Control recommends everyone 18 and older get vaccinated — whether or not they have had COVID, Cinti said.
“It makes sense because we know the protection rate with vaccination is about 95%, and we don’t know what the protection rate is for COVID patients,” he said. “I suspect it’s also that high, but we don’t know that.”