Last year, it seemed as though coronavirus reinfections were rare. Yes, they happened, but the vast majority of people who had already had COVID likely wouldnt contract the virus again anytime soon.

But recent data suggest reinfections are becoming more common, especially as new variants take hold. New Yorks health department recently published a report that shows a little over 4% of all COVID infections in the state have been reinfections and that nearly 87% of them have occurred since December 2021. Washington state reported that 45,312 people had reported a reinfection since September 2021 2.3% of those were hospitalized and 0.2% died.

The uptick in reinfections is likely influenced by two factors: one, that newer variants can evade the antibody response and reinfect, and two, that were now documenting reinfections more rigorously and getting a more accurate picture of how frequent they are.

Coronaviruses are known to infect people over and over again. In fact, its widely believed that the common cold coronaviruses that circulate today (and reinfect people frequently) originated from previous coronavirus epidemics. Many infectious disease doctors suspect that, as with those strains, we may be susceptible to reinfections but that the symptoms will become milder and milder with time.

As get more immunity, as our T-cells diversity and broaden, hopefully our second reinfection will not feel as bad as the first infection, said Monica Gandhi , an infectious diseases specialist with the University of California, San Francisco.

Heres how soon reinfections can occur with COVID now.

We now know that antibodies, which work to prevent infection in the first place, begin to dip a few months after vaccination or infection. In addition, as the coronavirus mutated, it became slightly less recognizable to the immune system.

Because of this, variants are able to outwit the immune systems first line of defense and reinfect us, according to Julie Parsonnet , an epidemiologist and professor of infectious diseases at Stanford University School of Medicine.

With omicron, we are seeing many cases in previously infected people, even when they had been vaccinated as well, Parsonnet said.

Pablo Penaloza-MacMaster , an assistant professor of microbiology-immunology at Northwestern University Feinberg School of Medicine, said that people who recently recovered from an infection or got boosted may be susceptible to reinfection in about six months.

Parsonnet noted shes heard of at least one patient who was fully vaccinated and double-boosted getting infected with omicron six weeks after their previous infection.

A recent study from Denmark found that, though very rare, reinfections with omicron subvariants can occur in as little as 20 days. Of the 1.8 million infections recorded between November 2021 and February 2022, 1,739 reinfections were detected within 60 days.

This doesnt mean that a couple of months after recovering, theres a good chance youll get COVID again. In fact, a pre-print study recently found that infections in people who have already had COVID were 90% less common than in people who had never been infected. Getting infected on top of the vaccine really boosts your antibody levels , and that should keep most people well-protected from infection for at least four months, Gandhi said.

Identifying who may be more likely to get reinfected isnt an exact science some people will be better protected and less at risk for reinfections depending on factors like their age, genetics and underlying health. The rate of reinfection also depends on the variant the type of mutations the virus has picked up and the viral load someones exposed to, according to Penaloza-MacMaster.