What to Know About Omicron BA.5 Reinfections

Throughout the pandemic, some found solace in the knowledge that, after the illness and social isolation that comes with a COVID-19 infection, their newly invigorated immune response would guard them against the virus for at least a few months.

But as the Omicron subvariant BA.5 sweeps the United States, it seems that more people are experiencing reinfections within a matter of weeks.

The Centers for Disease Control and Prevention is reporting more than 100,000 daily cases, driven largely by BA.5. This is likely a severe undercount—the real number may be several times greater.

A significant number of these cases are likely to be reinfections, though it’s hard to know for certain the exact portion, Laura Morris, MD, family physician and COVID-19 vaccine co-chair at University of Missouri, told Verywell. Different from other major waves, most Americans have now had COVID-19, making them vulnerable to reinfection.

Early research indicates that Omicron BA.5 has evolved to spread rapidly and skirt immune defenses, even in those who had previously recovered from COVID-19. This comes at a time when many restrictions are being lifted and people across the U.S. are foregoing precautionary measures like masking and social distancing.

“Many people who experienced Omicron infections in the winter or the early spring are, I think, certainly game to be reinfected with the BA.5 variant that will hit them sometime this summer,” Morris said.

While hospitalizations and deaths remain far below their peaks during the first Omicron wave, death rates are “still too high,” at about 350 per day, CDC Director Rochelle Walensky said during a press call.

How Often Can You Get Reinfected With Omicron?

The exact number of COVID reinfection cases is unclear because many people are testing at home or not at all. And the CDC doesn’t track reinfections, meaning it’s impossible to know just how many people have been sick more than once.

“We're seeing people who have symptoms and are choosing to avoid testing for various reasons,” Morris said. “The numbers are not in any way reflecting what's actually being experienced.”

Data from New York state shows an uptick in reinfections at the end of June. And some providers' clinical records show that some patients who previously tested positive are returning for COVID-19 care again, Krystina Woods, MD, an attending physician and Director of Infection Prevention at Mount Sinai, told Verywell.

Uncertain, too, is the precise timeframe in which someone can be reinfected.

It’s possible to be infected with COVID-19 twice within a few months. Woods said some patients who recovered from the earlier Omicron variants in late winter and early spring are very likely susceptible to catching BA.5.

But once the body has warded off one variant, it won’t readily succumb to the same variant. And because BA.5 will likely maintain its foothold for a bit longer, it’s unlikely that someone might fall ill with Omicron “every two to three weeks,” as one viral story claimed would happen.

“It appears that a previous Delta infection, for example, is not necessarily going to confer any extra immunity or any extra protection,” Woods said. “I would imagine there may be some protection from a more recent infection, but the prior strains don't seem to have any real measurable protection against this strain.”

Most people in the U.S. will never know for sure which COVID-19 variant they were infected with, since sequencing centers don’t share personalized information with patients.

Is BA.5 a More Infectious Variant?

BA.5 and its close cousin, BA.4, were first detected in South Africa this year. The variants quickly took hold in the U.S., too. BA.5 has already trumped BA.4 and now accounts for two-thirds of U.S. COVID-19 cases.

As with every iteration of COVID-19 that is responsible for case surges, BA.5 has successfully taken over due to mutations that make it more transmissible than the last dominant variant. Given how quickly the variant has taken hold in the U.S., some commentators have likened it to measles, the most contagious viral human pathogen.

But that calculation assumes that the virus is spreading in a community of people totally susceptible to the virus. After three years of COVID-19, nearly everyone in the U.S. has some protection against the virus, due to vaccinations and prior infection.

BA.5 may be more “fit” than other variants for two reasons, Woods said. For one, it has evolved to become inherently more transmissible. Some early research already shows BA.4 and BA.5 can better infect cells due to changes on the spike protein.

Secondly, BA.5 seems particularly adept at weaseling its way past immune defenses. The newest Omicron subvariants are so far removed from the original COVID-19 strain that the vaccines may be only marginally effective at mounting antibodies that can respond to them. BA.5 also looks different enough from previous subvariants, like BA.1 and BA.2, that it can escape immune defenses from prior infections.

“The immunity that you have from that BA.1 or 2 infection is going to be a little slower to respond—your immune system thinks that this is a different virus that is trying to infect it,” Morris said.

Still, the immune system isn’t left totally in the dark—immune cells will eventually kick into gear and likely protect against severe outcomes like hospitalization and death.

Just How Dangerous Is BA.5?

COVID-19 hospitalizations have increased over the past several weeks, though it’s not yet clear whether BA.5 is more likely to cause severe disease than other variants.

Some early research indicates that the existing COVID-19 vaccines—so far our best defense against the virus—lose a fair bit of neutralizing power against the new variants.

In one study, researchers found that in people who were vaccinated and boosted, antibody levels were 21 times lower against BA.4 and BA.5 than against the original strain of COVID-19.

Clinical trials showed that Moderna’s and Pfizer’s newly developed COVID-19 Omicron-specific vaccines were much better at protecting against BA.1 than were prior vaccines. But both vaccines induced antibody levels against BA.4 and BA.5 that were three-fold lower than against BA.1.

Still, most BA.5 infections remain mild to moderate for people who have immunity from prior infection or vaccinations. According to the CDC, there’s a 14-fold reduction in deaths among people who received a COVID-19 booster compared to those not boosted.

A mild illness can still be quite uncomfortable, Woods said, and some patients seem to have severe symptoms, even if they’ve recovered from a previous infection.

“It really does range from some individuals who are asymptomatic—whether it's their primary infection or a reinfection—all the way to people who have real flu-like symptoms—very bad body aches, chills, fatigue, headaches, fever,” Woods said. “There isn't really a very predictable type of symptom that we see.”

Woods said she’s seen fewer cases of patients who report shortness of breath since BA.5 became dominant. Still, many have a cough that lingers and lasting fatigue, regardless of whether it’s their first or second infection.

Given the apparent rise in hospitalizations and reinfections, Morris said it’s wise to resume “layering in protective measures,” like masking in crowded spaces and testing before social gatherings.  

This week, White House officials urged a return to masking and social distancing, and implored people over the age of 50 to receive a second booster shot if they haven’t already.

“You have to take two things into account. One is how much virus is going around in my community? And then how bad would it be for me if I were to get infected? When you think about those two things together, if you're a high-risk person right now, most communities in the United States right now are pretty full of COVID,” Morris said. “High-risk people need to not give up and give in to it. There will be lower risk times coming.”

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