Can you get COVID-19 more than once?

As COVID-19 cases continue to impact our communities, many people have been finding themselves sick more than once. While vaccination can offer significant protection from serious illness, reinfection is still a possibility.

Dr. Nancy Greengold, chief medical officer of Sharp Grossmont Hospital, answers three important questions about repeat cases of COVID-19.

Can you get COVID more than once?
Absolutely — some people get COVID-19 repeatedly. As we’ve seen, the coronavirus that causes COVID-19 is constantly mutating into new variants that challenge our immune defenses. Although a previous infection with one variant may have left you with some degree of immunity to that variant, you are at risk of becoming ill from a different variant.

There’s a small chance that you can even become reinfected with the exact same variant because immunity wanes within a few months. But again, the driving force behind COVID-19 reinfection is the virus’s constant process of mutation. Even the subtlest changes in the virus can help it bypass our existing immune response. And the newer, successful variants tend to be more infectious than preceding ones. We’ve seen reinfection more often since the omicron variant arrived than when delta was the main variant causing infections.

Will a second COVID infection be more mild?
To me, it makes intuitive sense that a reinfection might generally be milder, because individuals who have already developed an immune response to a first infection would be better equipped to fight a later one. And in many cases, this immune response would be strengthened by the additional immunity acquired through COVID-19 vaccination.

However, there is always individual variation with regard to symptoms and the way people perceive them. Although many people do report milder symptoms with COVID-19 reinfection, some actually report more severe symptoms.

The big picture is further complicated by the fact that there may be many people who are asymptomatic — that is, free of symptoms — with reinfection. Those who don’t undergo COVID testing are not showing up in our statistics. That means we may be underestimating the actual number of reinfections in a population — and may be overestimating their severity because the cases we’re counting as reinfections tend to be the more symptomatic ones.

But perhaps our data on the severity of reinfection are balanced by a factor that could skew them in the opposite way: Some people who are getting reinfected may have been asymptomatic with a first infection and think they are having a first infection when they are not. In that scenario, we’d be failing to recognize these cases as ones in which a person’s symptoms had worsened with reinfection. Overall, we’d be underestimating the severity of reinfections.

Interestingly, there are data suggesting differences in variants’ ability to cause any symptoms at all with reinfection. The United Kingdom’s Office for National Statistics indicates that the percentage of people having symptoms with reinfection increased from 20% with the alpha variant to 44% with the delta variant, and to 46% with the omicron variant.

Generally, the omicron variant is associated with milder illness than we saw with previous variants. We don’t know if this is because it is inherently milder, or because many more people are protected to some degree by immunity that they did not have when the delta, gamma, beta and alpha variants were spreading. Population-wide, the priming of our immune systems by exposure to the vaccines or any previous COVID-19 variant has continued to grant us meaningful protection from serious disease as we face new versions of the virus.

How soon after recovering can I get COVID again?
According to the CDC, there is a low risk of COVID infection for at least six months after full vaccination or previous COVID-19 infection. That risk is not nonexistent, though. Some sources say that it may take as little as a few weeks before you can acquire another infection.

In some cases, it could be that individuals haven’t fully recovered from previous infections, so the symptoms have simply returned. Some experts speculate that a very mild initial case of COVID-19 may not have prompted an immune response strong enough to protect against a later “dose of the virus.” In such cases, reinfection with the same variant could happen right on the heels of the previous illness.

Many, including Dr. Anthony Fauci, believe that reinfection with the same coronavirus variant is a rare event. They believe that most reinfections occur as the result of being exposed to a new variant, usually many months after a previous COVID-19 infection.

This is why there is so much interest in the development of new COVID-19 vaccines that target variants currently circulating. The challenge is that it takes time to develop these new vaccines and put them through adequate safety testing.

As frustrating as it may be to hear, wearing masks, avoiding crowds and getting vaccinated remain key ways to help prevent COVID-19 infection or reinfection. Most importantly, vaccination reduces your chance of having serious symptoms during an infection.