Much remains unknown about the coronavirus, such as why some healthy people get sick and die while others recover unscathed.
The mysteries also include how long natural immunity lasts after infection. But one thing is clear: experiencing COVID-19 is more risky than not. That’s why health experts recommend getting the coronavirus vaccine when one is authorized and available in your state — even if you’ve already been sick and recovered.
Conflicting research shows that the level of antibodies, or proteins that fight viruses and bacteria, can differ drastically from one person to the next.
One non-peer reviewed study published last month found that coronavirus patients still had special immune cells that could fight the infection eight months after recovery, suggesting they could last for years. However, others have come up with immunity timelines of about four months.
The Centers for Disease Control and Prevention says more research is needed to fully understand how long a COVID-19 survivor is protected from getting the disease again.
Despite the unknowns, survivors may be advised to get vaccinated anyway because of the “severe health risks associated with COVID-19 and the fact that re-infection with COVID-19 is possible,” although rare, the CDC says.
Besides, infectious diseases experts say there’s nothing to lose.
“There’s nothing deleterious about getting a boost to an immune response that you’ve had before,” Dr. Marion Pepper, an immunologist at the University of Washington in Seattle, told the New York Times. “You could get an actually even better immune response by boosting whatever immunity you had from the first infection by a vaccine.”
This means people who have had COVID-19 don’t have to rush ahead of those with no immunity to get vaccinated either, experts say.
Natural immunity, no matter how long it lasts, may protect you long enough to reach spring, when the general public is expected to get vaccinated.
No evidence suggests vaccine is unsafe for COVID-19 survivors
There also isn’t any evidence that the vaccine could be unsafe for people who have recovered from the coronavirus.
Both the Pfizer-BioNTech and Moderna vaccines — the first two in line for federal authorization this month — didn’t test their products in people sick with symptoms at the time of vaccination or who had previously been infected.
But Dr. Moncef Slaoui, the chief science adviser for Operation Warp Speed, said that up to 10% of participants in both trials had unknowingly been infected with the coronavirus before, according to NBC News, meaning the vaccine proved safe for survivors, too.
Some experts say more research is needed to be certain.
“There haven’t been any serious adverse events that make me think this would be a major issue, but I think that analysis has to be done,” Dr. Sarah Fortune, chair of immunology and infectious diseases at the Harvard T.H. Chan School of Public Health, told NBC News. “The first question is about safety, but then the second question is: Is there any added benefit?”
Vaccine may benefit people who had mild cases the most
Some studies have shown that the milder someone’s COVID-19 case, the faster their antibody concentration disappears, while others find similar immunity reactions regardless of disease severity.
“Those people [with mild cases] might benefit more from the vaccine than others would,” Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, told the New York Times.
Hanage said different immune responses could stem from different levels of exposure to the virus.
“The longer time you spend in that environment — so minutes or hours in there — the more virus you breathe in, the more it can build up and then establish infection,” Erin Bromage, a comparative immunologist and biology professor at the University of Massachusetts Dartmouth, told CNN in May.
“So it’s always a balance of exposure and time. If you get a high level of exposure, it’s a short time (to infection, and if you get a) low level of exposure, it’s a longer time before that infection can establish,” he told the outlet.
Only time will tell if the coronavirus will be a seasonal illness that returns in waves each year, similar to the flu.
Unlike these annual viruses, those that cause measles, mumps and Hepatitis B usually offer lifelong immunity after infection, so their vaccines just mimic what the virus naturally does in the body.
But viruses that cause the common cold, and possibly the one that brings about SARS-CoV-2, don’t offer this guaranteed protection.
“We’re thinking that with the [COVID-19] vaccines, we should be able to do better than nature,” Peter Doherty, a Nobel Prize-winning immunologist at the University of Melbourne’s Doherty Institute in Australia, told Inside Science.