How Does Getting a Breakthrough Covid Case Affect My Immunity?

Like many New Yorkers, Domenica D’Ottavio contracted Covid-19 over the Christmas holidays. Her head clogged with congestion, her body ached; she coughed and spiked a fever.

But she also had another surprising symptom: relief.

“It was just a different feeling,” said Ms. D’Ottavio, who had been fully vaccinated and boosted before getting infected. “You don’t realize until it’s over that you’ve been walking around with a tiny bit of fear in the back of your mind.”

Ms. D’Ottavio still wears masks and takes a test before she visits her mother. But she also planned a “post-Covid” trip to Florida for her sister’s birthday, and now goes to bars and dates without thinking about the pandemic. She even swapped straws with a friend who had also recently recovered from Covid, so they could try each other’s drinks.

“We all feel like superheroes,” she said about her friends who have had breakthrough infections. “We all feel like we can do anything.”

Nearly 800,000 new cases are being reported in the United States each day, according to a New York Times database, most caused by the fast-spreading Omicron variant, and the true number of infections is likely much higher because so many cases go unreported. Although many people are quickly recovering, the Omicron surge poses a particular risk to the unvaccinated and has put enormous strain on hospitals and health care workers.

But among the vaccinated and boosted, getting infected with the Omicron variant also appears to be contributing to a psychological shift, as people realize they have probably gained at least a short-term natural boost to their immune system. Scientists call it “hybrid immunity,” which results from the combined protection of pre-existing vaccine antibodies and natural antibodies from a breakthrough infection.

Google searches for the term “super immunity” increased by 550 percent in the United States over the last three months, according to Google Trends data. Searches for “hybrid immunity” increased by 230 percent over that time.

While some doctors and immunologists agree that hybrid immunity offers an additional layer of defense against the virus, they urge caution, noting that the strength of that protection can vary by individual and may wane over time.

“It’s the best immunity you can get,” said Shane Crotty, a virologist at the La Jolla Institute of Immunology. “But I wouldn’t think of hybrid immunity as being a force field that can completely stop it no matter what.”

Experts also caution against trying to get infected on purpose as a way to gain hybrid immunity. “I really worry that people will intentionally get infected so they can get to this ‘new normal’,” said Dr. Celine Gounder, an infectious disease specialist at Bellevue Hospital Center. The virus is unpredictable, and even young people can become very sick. “Something could go wrong, and they could end up in the hospital,” she said. In addition, it’s impossible to know who might develop long Covid after an infection.

How much does hybrid immunity protect you?

The immunity boost of a natural infection may be akin to getting a fourth dose of vaccine, said Dr. Peter Chin-Hong, an infectious disease expert at the University of California, San Francisco. Hybrid immunity may also occur if you get infected before getting vaccinated or a booster.

Here’s why. The first time you get vaccinated or infected with a virus, it takes your immune system a little time to respond. But your immune system has a long memory. It reacts more quickly and ramps up more antibodies the next time it detects the virus. The effect appears to be even more pronounced in people who’ve been both vaccinated and infected.

A recent study showed that vaccinated health care workers with breakthrough infections had significantly higher levels of antibodies compared to a vaccinated control group that had not had natural infections. Fikadu Tafesse, an immunologist at Oregon Health & Science University who helped conduct the research, said that although the study was done before the Omicron wave, the findings suggest a drastically elevated level of protection after a breakthrough infection.

“Super immunity is maybe an overreach, but we know the most recent studies show there’s hybrid immunity, really due to immune players known as memory B cells,” said Anita Gupta, an adjunct assistant professor of anesthesiology and critical care medicine at Johns Hopkins University School of Medicine. “When some of the short-lived immune cells go away, these memory B cells are going to last a while.”

But here’s the bad news: Exactly how much extra protection you get and how long it lasts will vary by individual, said Akiko Iwasaki, an immunologist at Yale University. And a person who is immunocompromised or older or otherwise at higher risk for severe disease likely will generate fewer antibodies than a young, healthy person, and their antibody levels may also drop more quickly.

It’s also not clear whether the severity of the illness affects the level of hybrid protection. A person with severe symptoms may have been exposed to a greater amount of the virus, which would trigger more antibodies and thus more protection, Dr. Iwasaki said. A person who was asymptomatic may not have as robust of an immune response to the virus and may be more susceptible to reinfection.

“Going back to 2019 behavior is a little premature,” Dr. Iwasaki said. “It’s really just playing the lottery, because you don’t know how many antibodies you’ve generated.”

In the short term, recovering from a breakthrough infection means you’re “almost certainly” protected against severe disease after both vaccination and infection, said Dr. Adam Ratner, director of the division of pediatric infectious diseases at Hassenfeld Children’s Hospital at N.Y.U. Langone.

But there isn’t enough data yet on how much hybrid immunity protects you from a mild or asymptomatic breakthrough infection or from spreading the virus to others. And you might be susceptible in the future to any new variants that emerge. Some vaccinated people who previously were infected with the Delta variant, for example, have been reinfected with Omicron, said Jennifer Gommerman, an immunologist at the University of Toronto.

Can I party like it’s 2019?

Experts warned against being cavalier about Covid precautions after recovering from a breakthrough infection. The number of Americans getting infected every day remains staggeringly high, and it’s unknown whether the population is building enough natural immunity to help us reach the day when the virus becomes a manageable part of daily life.

“Mid-surge, it’s very hard to say that increasing risk makes sense for anybody,” said Dr. Paul Sax, an infectious disease expert at Brigham and Women’s Hospital and professor at Harvard Medical School.

But for many of those who are young, vaccinated and otherwise healthy, recovery from a breakthrough infection can bring some peace of mind. For at least the first three months following a breakthrough infection, if you are not at high risk for severe disease, you should feel very confident about your level of protection, particularly if you are boosted, said Ashish K. Jha, dean of the Brown University School of Public Health.

“Could you get reinfected? Yeah, if somebody in their most contagious moment hacks in your face over and over, maybe,” Dr. Jha said. But “a normal interaction in a restaurant or a bar” is likely safe, he said.

But other experts warned that even if you have hybrid immunity, your risk of getting infected again — and potentially spreading the virus to others — isn’t zero. It’s still a good idea to take precautions and get tested before spending time with vulnerable people.

“You have to remember there are vulnerable people in the community, and we have to continue to do things like wearing masks,” said Dr. Gounder. “It’s not just about protecting yourself, it’s about protecting other people.”

Ilana Horowitz, a 44-year-old social worker in Tuckahoe, N.Y., said she and her wife and their 6-year-old twins all came down with Covid in early January. She said that at least in the short term, she feels like she can provide “a sense of normalcy” for her kids. She’s no longer worried about them missing school or missing work to take care of them. “There’s a freedom in that for sure,” she said.

Patricia Piekarski, 40, a human resources professional in Rockland County, New York, remembers how anxious she felt after her boyfriend had been exposed to the virus a few months ago. She recalled how she tripped and cut her knee on her way to find a rapid test, and scanned the drugstore aisles with blood seeping through a hole in her jeans.

But now that level of panic and concern is behind her. In early January, she and her boyfriend both had mild breakthrough infections and have since recovered. While she still wears a mask and takes precautions, she now feels safer making plans to meet her brother’s new baby and to eat indoors at restaurants. “I’m going to start texting friends saying, ‘Hey, if anyone else had it, let’s hang out,’” she said.