NEW ORLEANS, La. (WVUE) - With no COVID-19 vaccine approved yet, there is a lot of focus on antibodies, proteins that develop after someone has been infected with the virus. Antibodies are supposed to help fight off infection and provide protection against re-infection. But UCLA research published this week in the New England Journal of Medicine found that in some people the antibodies disappeared or decayed quickly.
Specifically, the researchers discovered a sharp drop in antibodies over the first three months after infection, decreasing by roughly half every 36 days. They said if that rate was sustained the antibodies could be gone entirely in about a year.
Experts from Tulane and Johns Hopkins Universities reacted to the findings and discussed how antibodies work in general.
Robert Garry, PhD., is a Tulane virologist and professor of microbiology and immunology who is involved in various efforts involving the novel coronavirus.
“What the study showed was is that people that have mild or asymptomatic infections, you know, develop an immune response, it’s typically not as high as in people that develop serious illness or have to be hospitalized,” said Garry. “And what the investigators also found was that those antibody levels tend to drop off a little faster than what we would hope for, or what we might expect.”
Arturo Casadevall, M.D., PhD., is a professor and Chair of the Department of Molecular Microbiology at the Johns Hopkins School of Public Health and was made available for comment through SciLine.
He said it is plausible that some people with mild COVID-19 infection would lose antibodies quickly.
“Yes, actually it makes sense for all we know. It appears that COVID-19 disease is an inflammatory disease and that the worse you get, the stronger the inflammation and the antibody you make, now it doesn’t mean that antibody is not protective, what it means is you’re making this antibody as you’re getting sick, but that antibody will be there after people recover,” said Casadevall.
Still, he said people with milder disease do not mount as strong of an immune response.
"So that information is consistent with what we know."
Garry was asked if it is conceivable that people infected with the virus who shed antibodies quickly could be re-infected soon after they recover.
“The question about reinfection is an important one but so far there have been about 10 million people infected with this coronavirus around the world and no one example, at least a clear cut example of somebody being re-infected, so it would be unusual in a virus infection to find a situation where you could be infected and then a few minutes later be re-infected with the same virus. That usually doesn’t happen, there is no evidence that is happening with the SARS-CoV-2,” answered Garry.
Casadevall said evidence shows that some immunity is provided after infections.
“I think there is a good likelihood based on everything we know from immunology that they will retain memory, so if they run into the virus again they will be a lot better protected, so it’s likely that there will be protection, as to how long it will last that we don’t know,” Casadevall stated.
Herd immunity has not happened; that involves having a large portion of the population infected, so that the spread of a virus is significantly impeded.
“When you get to high numbers of those people in the population then the virus will naturally not be able to sustain itself because it depends on new infections to keep going and then the pandemic will be over,” Garry said.
But because that has not happened, they say getting a vaccine approved is critical.
“Having an effective vaccine that gives some level of protection over some period of time has been from the beginning our best opportunity to shut this pandemic down,” Garry stated.
“I’m very optimistic,” said Casadevall. “That waning of immune responses is normal. That is why, for example, we often have to get booster doses, why you have to get your Tetanus vaccine every 10 years.”
The researchers said theirs is the first study to carefully estimate the rate at which antibodies against the new coronavirus disappear from the body.