A lot has changed since the pandemic started. Here's what the experts say about reinfection, COVID-19 immunity and how long it lasts.
As COVID-19 has mutated into new variants of the virus, scientists' understanding of immunity and public health measures have changed, too. Mask mandates have fallen in some cities and public spaces (though some areas or businesses may require them), public health officials are considering an annual simplified vaccine strategy in the US and World Health Organization officials this week said people in higher-risk groups, not those of medium or low risk, should be the priority in vaccine plans moving forward.
These developing plans reflect a new state of the pandemic, once the emergency expires in the US in May, and a new way to handle COVID-19, which has been circulating in various forms of omicron since late 2021. While the burden of COVID-19 is simmering at much lower levels than earlier in the pandemic, the fact that the virus is still around making people sick will eventually spur the question (if it hasn't already): What happens when you get COVID-19 again?
COVID-19 reinfection happens when you have the virus for a second, third or fourth time, or more. While confirmed cases of it were relatively uncommon in the early stages of the pandemic, many people have gotten COVID-19 more than once, or will get it again in the future.
Here's what the experts say about immunity arising from past infections and vaccines, what you should know about the risk of long COVID after another bout of COVID-19, and more.
A meta-analysis of 65 studies published in The Lancet in February found that protection against severe disease from prior infection with COVID-19 is high with all past variants, while protection against reinfection, or getting sick again, was lower and declined pretty rapidly with the omicron variant (BA.1). Perhaps most importantly, the study found that protection against severe disease for COVID-19, in general, remained high for 40 weeks (10 months).
Dr. Christopher Murray, director of the Institute for Health Metrics and Evaluation and one of the authors of the analysis, says that when you talk about COVID-19 immunity, you need to consider it as two parts: protection against severe disease, and protection against infection.
While protection against getting infected with COVID-19 again after you've already had it is "not great," Murray said, "immunity to prevent severe disease and death is really quite good."
Someone's risk of severe disease or being hospitalized with the virus will depend on different factors, including their age (older adults have the highest risk) or medical conditions. But in terms of your individual immunity, take note of the last time you had your immune system stimulated against COVID-19.
"The key thing to the individual is to remember when was the last vaccination you've had, or the last time you were sure you got infected," Murray said.
"We know there's sustained immunity for at least 10 months," he said, referring to protection against severe disease. "That'll tell you when the clock starts ticking about immunity."
"I think now we're seeing the value of natural immunity that we didn't know a year or two ago," said Dr. Mike Sevilla, a family physician who practices in Ohio. "The population in general has already been exposed to the COVID virus in one way or another," Sevilla added, whether it was from the vaccine, an infection or both.
It also appears we've officially said "goodbye" to the idea of herd immunity -- the concept that enough of the population having immunity would also work against COVID-19 and would stop its spread.
"You're not gonna stop the transmission of the virus just by a lot of people getting infected or vaccinated," Murray said. "That's a pretty big change in thinking from two years ago, I'd say."
Because the variant someone is infected with can partly determine the severity of their illness, how sick someone gets with a reinfection might depend on whether they were infected with a version of omicron or an earlier variant, according to Sevilla.
"It really depends on when they had their infection, as opposed to whether they had it two or three times," he said.
According to the US Centers for Disease Control and Prevention, symptoms during your reinfection with COVID-19, compared to the first illness, are likely to be less severe. However, some people get more severe illness, the agency notes. Testing, treatment and isolation guidelines during your second or third COVID-19 infection are also the same as for your first.
Long COVID is a lingering condition that results in someone experiencing lasting symptoms or mental or physical changes after their body has cleared the infection. Does getting infected again increase the risk for long COVID?
"It's hard to answer that one, but we have seen a pretty strong link between severity and risk of long COVID," Murray said. That is, people who need to be hospitalized or get very sick with the virus have a higher risk of long COVID in general.
According to an article by the American Medical Association, each time you get COVID-19, your risk for developing chronic health issues, including organ damage, goes up. Damage to different organs in the body is one of the many different ways long COVID affects people.
Researchers who published a large review on long COVID earlier this year in Nature Reviews Microbiology wrote that early research suggests an increasing risk of long COVID symptoms with reinfection, but that early evidence also shows a flipped relationship with certain immune responses in people with long COVID possibly making them more susceptible to getting the virus again.
"We're definitely in a better place, public health-wise, than we were at the start of the pandemic," Sevilla said, adding that his focus is on his older and higher-risk patients, which include people with diabetes, heart disease and those who survived cancer.
Murray says that for many adults who don't have a health condition that puts them at higher risk of severe disease, the effect of COVID-19 is milder and resembles influenza -- a stark contrast to earlier stages of the pandemic when COVID-19 was much more severe, Murray added. But COVID-19 still does not have a flat risk profile.
"The very elderly are still at high risk, and if they haven't recently had a booster or been recently infected..then that's a real risk," Murray said, noting that people who are immunosuppressed should also "err on the side of great caution" when considering how much time has passed since their last vaccine or infection. Updated boosters that target the omicron variant are available for children and adults, as long as it's been at least two months since your last shot. (Learn more about staying up-to-date on COVID-19 vaccines on the CDC's website.)
"People need to change their mindset," Murray said. "It's not 'you got vaccinated, you're done' or 'you got infected, you're done.' Keep track of when you last had something that stimulated your immunity."
Older adults and people with certain medical conditions are also eligible for treatments including Paxlovid, which cuts the risk of being hospitalized or dying in high-risk patients. If you have symptoms of COVID-19 or get a positive test, and you are at high risk of severe disease, reach out to your doctor or pharmacist as soon as possible to see your treatment options. As outlined in a Medscape post by Dr. Eric Topol, editor-in-chief of the publication and executive vice president of Scripps Research, the people who need treatment the most may not be getting it.
The fact that COVID-19 has become a more manageable disease for many people partly reflects that we haven't had a significantly new variant since late 2021 or early 2022 when omicron became dominant and started mutating into different (and more contagious) versions of itself. Murray says that the risk for a new dominant variant which causes more severe disease or has immune escape (gets around protection from vaccines or past illness) is there, and would be "very concerning."
But relatively speaking on the variant front right now, Murray said, "We're doing well."