What are the FLiRT variants?

Over the winter, the dominant COVID-19 variant was JN.1, which spread globally. However, a new variant called KP.2, or FLiRT due to the location of its mutations, began to emerge in March.

There are several different FLiRT variants, including KP.2, KP.1.1, and KP.3. In a two-week period ending May 11, KP.2 made up 28.2% of COVID-19 cases in the United States, while KP.1.1 made up over 7% of cases.

According to some health experts, KP.2 and KP.1.1 could be more transmissible than previous COVID-19 variants. So far, early data suggests that KP.2 may be "rather transmissible" since its new mutations help "its ability to transmit, but also now evades some of the pre-existing immunity in the population," said Andrew Pekosz, a virologist at Johns Hopkins University.

Currently, there's no evidence to suggest that the FLiRT variants cause more severe illness than previous COVID-19 variants. Some of the symptoms associated with the FLiRT variants include fever or chills, cough, sore throat, fatigue, a loss of taste or smell, and brain fog.

"The CDC is tracking SARS-CoV-2 variants KP.2 and KP.1.1, sometimes referred to as 'FLiRT,' and working to better understand their potential impact on public health," the agency said. "Currently, KP.2 is the dominant variant in the United States, but laboratory testing data indicate low levels of SARS-CoV-2 transmission overall at this time. That means that while KP.2 is proportionally the most predominant variant, it is not causing an increase in infections as transmission of SARS-CoV-2 is low."

Could these variants lead to another COVID-19 surge?

Currently, COVID-19 cases and deaths are declining, but health experts say the FLiRT variants' potential to evade immunity could lead to a spike in cases as people gather for summer holidays.

Immunity may also be waning since few people received updated COVID-19 vaccines last fall. According to CDC, only 22.6% of adults reported receiving an updated vaccine since September 2023, though vaccination increased by age and was highest among those ages 75 and older.

"We've got a population of people with waning immunity, which increases our susceptibility to a wave," said Thomas Russo, chief of infectious disease at the Jacobs School of Medicine and Biomedical Sciences at the University of Buffalo.

Otto Yang, associate chief of infectious diseases at the University of California, Los Angeles' David Geffen School of Medicine, said that while healthcare systems can manage COVID-19 waves, immunocompromised and older adults at a higher risk of developing severe disease are often overlooked.

"Those people unfortunately carry a heavy burden," Yang said. "I'm not sure there is a good solution for them, but one thing could be better preventive measures."

However, COVID-19 protections that were common in the past, including testing before events and mask requirements, have now fallen by the wayside, the Washington Post reports. Even events with preventive measures in place have faced difficulties enforcing them.

"Culturally we are coming away from it as a society, so it gets much harder to ask people to really be consistent, because they aren't doing it anywhere else," said D Schwartz, who organized a large LGBTQ+ community gathering event in Washington, D.C. "You go into a movie theater now, you see maybe five people wearing a mask."

Declining data collection has also impacted how people view the current COVID-19 situation. Although CDC still tracks coronavirus levels in wastewater and the percentage of ED visits with a diagnosed case of COVID-19, hospitals stopped reporting confirmed COVID-19 cases in April.

"We're kind of shooting blind now," said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Texas Children's Hospital Center for Vaccine Development. Hotez also noted that a lack of data collection will make it harder to convince Americans that COVID-19 is enough of a threat to require continued vaccination.

"If a wave materializes this summer, we're less poised to navigate the rough waters," said Ziyad Al-Aly, an epidemiologist and long COVID researcher at the Veterans Affairs health system in St. Louis. (Hauari, USA Today, 5/15; Binnicker, Forbes, 5/21; Johnson, Forbes, 5/22; Nirappil/Malhi, Washington Post, 5/26)

In March 2020, the World Health Organization declared COVID-19 a global pandemic. Here's what we've learned about the virus since then, what we still don't know, and its ongoing impact on both people's health and society at large.