Will the New COVID Variant NB.1.8.1 Cause a Summer Surge in the U.S.?

It’s not too late for adults 65-plus to get their spring shot

Rachel Nania,

AARP

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En español

Published June 05, 2025

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Public health experts are tracking a new COVID-19 variant that some warn could contribute to a spike in new cases as we enter the summer months.

The strain, known as NB.1.8.1, is a descendant of the omicron variant, and global health officials suspect it’s contributing to rising cases and hospitalizations in other countries where it’s more prominent. NB.1.8.1 has been detected in the U.S., and although it is not one of the top circulating strains, some experts believe it could surpass the others.

Here’s what we know so far about the latest coronavirus variant and how older adults can protect themselves from COVID-19 this summer.

Why the NB.1.8.1 variant is worrying doctors

What’s keeping experts’ eyes on NB.1.8.1? It has several mutations on its spike protein — the area of the virus that binds to the cells and allows the virus to enter — that set it apart from the currently dominant variant (LP.8.1), says microbiologist Matthew Binnicker, director of clinical virology at the Mayo Clinic. And in some studies it’s been shown to be more transmissible, meaning it can spread more easily from person to person, Binnicker adds.

“And so they’re thinking it may really take off in terms of becoming a predominant strain of the virus and cause more infections as we enter into the summer months,” he says.

Lower vaccination rates and waning immunity from previous doses could contribute to a rise in cases. Less than a quarter of adults in the U.S. have received a COVID-19 vaccine during the 2024-2025 season.

A spike in COVID-19 cases and hospitalizations during the summer is not unusual. Hospitalization rates started to creep up in July 2024 and peaked in late August, and previous years saw a similar pattern.

“We’ve got five years of experience with COVID, and we’ve seen almost every year a dual peak or increased incidence of COVID-19 — one during the winter months and then a second during the summer months,” Binnicker says. And there’s no reason to think this year could be any different.

What are the symptoms of the new COVID variant?

While it may be better at infecting more people faster, the World Health Organization says there’s no indication that NB.1.8.1 causes more severe illness. Still, it’s important to understand that you can still get a severe case of COVID-19 from this or any other variant, so monitor your symptoms and take a test if you experience any.

According to the U.S. Centers for Disease Control and Prevention, common symptoms of COVID-19 include:

Fever or chills
Cough
Shortness of breath or difficulty breathing
Sore throat
Congestion or runny nose
New loss of taste or smell
Fatigue
Muscle or body aches
Headache
Nausea or vomiting
Diarrhea

Federal data shows that COVID-19 hospitalizations are not limited to the typical respiratory virus season and that the risk of hospitalization from an infection for older adults remains high from May through September.

Can older adults still get a COVID booster for summer?

Even though the currently circulating variants, including NB.1.8.1, have drifted from the version of the virus that the 2024-2025 coronavirus vaccines target, Binnicker says the available shots can still help protect against serious complications from COVID-19. This is especially important for adults 65 and older, who were advised to get a second dose of the vaccine in the spring to boost waning immune defenses.

Find COVID-19 vaccines in your state

AARP's 53 state and territory COVID-19 vaccine guides can help you find vaccines near you and provide the latest answers to common questions about costs, eligibility and availability.

If you haven’t received this second shot, it’s not too late to roll up your sleeve for one, says infectious disease physician Tyler Evans, M.D., CEO of the Wellness Equity Alliance and a research associate professor at the University of Southern California’s Keck School of Medicine. Also, he adds, antiviral medications like Paxlovid still work against NB.1.8.1 and other variants, so if you do catch COVID, talk to your doctor about treatments that can keep a mild case from turning severe.

“If you start to experience any symptoms of COVID — cough, sore throat, fever, runny nose, body aches — get tested,” Binnicker says. And even if your sneezing and coughing aren’t due to COVID, remember to stay home or mask up around others, he adds.

Details on what the COVID-19 vaccines for 2025-2026 will target — and who should get one — have yet to be determined. Medical advisers to the federal government are scheduled to meet in June to discuss recommendations for the new shots, which typically roll out in the fall.

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