fter the Omicron variant caused massive numbers of infections this past winter, lots of people looked on the bright side, hoping it would be “a free shot for the country,” says Eli Rosenberg, deputy director for science at the New York State Department of Health’s Office of Public Health. Even though many people were infected by the contagious Omicron variant, they will be protected from future infections. The theory is true.
But that hasn’t turned out to be true. Many people—even those who are vaccinated, boosted, and previously infected—are again testing positive as Omicron relatives like BA.2 and BA.2.12.1 circulate throughout the country.
Although not every state tracks reinfections in their data, some are experiencing an uptick. The week ended May 12th saw Indiana reporting 14% more cases than the 10% reported the week prior. New York and North Carolina are reporting similar numbers, although slightly lower. These numbers could be much higher because official counts of cases have been skewed by widespread home testing.
“This is going to keep cycling through the population,” Rosenberg says. “Every few months you could keep getting it.”
Unlike viruses like measles, which strike once and leave behind lifelong immunity, SARS-CoV-2 has proven that it’s capable of reinfecting people since at least the summer of 2020. The U.S. Centers for Disease Control and Prevention recently warned that people who have had COVID-19—around 60% of the U.S. population, by the agency’s estimates—should not assume they won’t get sick again.
Both COVID-19 vaccinations and prior disease provide some protection against future illnesses, but they’re better at preventing severe disease than infection, says Dr. Rachel Presti, medical director of the Infectious Disease Clinical Research Unit at the Washington University School of Medicine in St. Louis. Reinfections are likely to be mild, she says, but they’re also probably going to keep happening.
“When you have immunity, it’s protecting you When you get sick. It doesn’t really protect you From getting infected,” Presti says. “It’s not like an external wall. It’s more like guards inside the gates.”
Rosenberg says there’s always a spike in reinfections when a new variant starts to surge, since antibodies from one strain may not hold up well against the next. Experts say that reinfection is not likely for more than 90 days after a COVID-19-related illness. But that’s only true if a new variant doesn’t pop up, Rosenberg says, and the virus “keeps switching on us every few months—faster than 90 days.”
Newer versions of Omicron are better than older variants at getting around immune defenses. Research shows that Omicron was responsible for a large number of reinfections and breakthrough infections. This is due to its mutations, which made it more contagious and allowed it to bypass natural immune blocksades.
It’s too early to say exactly how BA.2.12.1 will compare. But two studies published in May as preprints—meaning they were not peer-reviewed prior to publication—suggest that newer Omicron subvariants, including BA.2.12.1, could be even better at evading prior immunity than the original Omicron strain.
It’s early, but preliminary findings suggest “it’s both very highly transmissible and it has escape mutations…that make it somewhat resistant to previous infection or to vaccination,” says Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children’s Hospital and dean of the National School of Tropical Medicine at Baylor College of Medicine.
Presti claims BA.2.12.1 has caused many more infections than she expected. This is due to its similarity with the Omicron strain which infected large swathes of the U.S. populace. “Particularly [with] people who were vaccinated and then got Omicron, it surprises me that they’re getting sick again,” she says.
Good news: Vaccinations and previous infections are still effective in preventing severe disease. Hotez states that people who are immune to the virus and have had previous bouts of it are more protected than those who were infected by the virus. Everyone should keep up-to date with their vaccines. Combined with “situational awareness”—like wearing a protective mask or skipping large, mask-free gatherings if COVID-19 is rampant in your area—Hotez says that’s our best defense, at least right now. (Other tools, such as nasal vaccines that could theoretically stop transmission, boosters that could protect against multiple variants, or protein-based shots that could provide more durable protection, are in the works, but they’re not here yet.)
It is unknown what this virus might do in the future. Presti says it’s starting to look like it may one day resemble regular coronaviruses, such as those that cause the common cold. It is possible to catch the common flu multiple times in a year but rarely cause serious illness.
But there’s a long way to go before COVID-19 is truly comparable to a cold, Presti says. Each day hundreds of COVID-19-infected people are brought to U.S. hospital beds. People who have not been vaccinated or are immunocompromised can become particularly ill. However, even mild cases of the virus may lead to complications such as Long COVID. This condition can often last for many years.
SARS-CoV-2 is not known to cause mild illnesses like the common cold. The virus is continually evolving, and it’s impossible to predict what the next variant will bring—but it’s safe to assume reinfections are no longer the rarities they were once thought to be.
Here are more must-read stories from TIME