2 new COVID variants called “FLiRT” are spreading in the United States. What are the symptoms ?

The respiratory virus season may be coming to an end in the United States, but a new group of COVID-19 variants is circulating, sparking concerns about a potential summer surge.

The family of variants, nicknamed “FLiRT” after their mutations, includes KP.2, which is now the dominant variant in the United States. In recent weeks, KP.2 has rapidly overtaken JN.1, the omicron subvariant that led to a surge in COVID cases last winter.

Currently, KP.2 accounts for one in four infections nationwide, according to the latest data from the U.S. Centers for Disease Control and Prevention.

During a two-week period ending April 27, KP.2 accounted for nearly 25% of cases in the United States, compared to approximately 10% during the previous two-week period ending April 13. After KP.2, the second most common variant is JN,1, which accounts for 22% of cases, followed by two subvariants JN.1, JN.1.7 and JN.1.13.1.

Another variant of FLiRT, called KP.1.1, is also circulating in the United States, but it is less widespread than KP.2. It currently accounts for about 7.5% of infections nationwide, according to the CDC.

Although cases and hospitalizations are declining and the country is in the midst of a COVID-19 lull, the new FLiRT variants are stoking concerns about a new wave of infections this summer.

Will there be another wave of COVID-19? What are the symptoms of FLiRT variants? Are vaccines still effective? We spoke with experts to find out more.

What are the variations of FLIRT?

The FLiRT variants – KP.2 and KP.1.1 – are spinoffs of JN.1.11.1, a direct descendant of JN.1, and were initially detected in wastewater samples from across the country.

The new variants have two additional mutations that set them apart from JN.1 and appear to give them an advantage over previous variants, said Dr. Albert Ko, an infectious disease physician and professor of public health, epidemiology and medicine. at the Yale School of Public Health, tells TODAY.com.

The nickname “FLiRT” is based on the technical names of their mutations, according to the Infectious Disease Society of America.

Much like other strains of COVID-19 that have gained dominance in the United States over the past year – JN.1, HV.1, EG.5 aka Eris and XBB.1.16 or Arcturus – the FLiRT variants are part of the omicron family.

The emergence of KP.2 and other FLiRT variants is “the same old story,” Andrew Pekosz, Ph.D., a virologist at Johns Hopkins University, told TODAY.com. The SARS-CoV-2 virus mutates and gives rise to a new, highly contagious variant, which becomes the dominant strain. “The time frame in which this happens, in three to six months, is much faster than that seen with other viruses like the flu,” says Pekosz.

Are the new variants more transmissible?

“It’s still early, but the first impression is that this variant (KP.2) is quite transmissible,” Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, told TODAY.com.

The proportion of cases caused by KP.2 is increasing while the proportion caused by other variants is decreasing, suggesting that KP.2 has characteristics that give it an advantage, experts note.

KP.2 looks a lot like its parental strain JN.1, says Pekosz, which is very contagious. “Except it has these two mutations. … I think these two mutations together make KP.2 a better virus in that it retains its ability to transmit, but also now evades some of the pre-existing immunity in the population,” says Pekosz.

According to the CDC, more than 97% of Americans have natural or vaccine-induced antibodies to the SARS-CoV-2 virus, but this immune protection fades over time.

Low vaccination rates and waning immunity create a vulnerable population, which could allow FLiRT variants to take hold. Only time and more data will tell, experts note.

Laboratory studies suggest that KP.2 is mutated enough that current vaccines and immunity from prior infection provide only partial protection, Schaffner says. “We will have to see how true this is, but it seems that over time it is becoming a more prominent variant,” he adds.

“The emergence of the KP.2 is still very early, but I don’t think we need to sound the alarm yet,” Ko says.

Will there be a summer surge?

It’s too early to tell whether the FLiRT variants will cause a summer wave or surge, experts note. However, it is clear that COVID-19 is still circulating and will not take a break.

“We’re seeing these infections throughout the year, at modulated levels. … We’re probably not at the point yet where we’ll see COVID disappear completely at any time of the year,” Pekosz says.

Test positivity, which is an early indicator of case levels, is 3% as of April 20, down 0.4% from the previous week and down sharply from around 12% in mid- January, according to the CDC. (CDC no longer tracks total U.S. cases)

“We’re not seeing a lot of hospitalizations, and we’re certainly a lot lower than in the winter, so I would say right now we’re at a low point, which is reassuring,” Ko says.

Wastewater data released by the CDC shows that the level of COVID-19 viral activity is currently “minimal” – it was considered high or very high for most of January and February.

“It seems like transmission is pretty low right now, and that makes sense because the biggest spikes usually occur in the winter, when people are indoors and in more contact,” Ko says.

In the past, COVID-19 has caused summer waves, experts note, which are often smaller than winter waves. “I don’t think we’ll see any massive increase in cases,” Pekosz says.

Speculating on current COVID-19 trends, Ko says: “KP.2 could cause a small wave, but not necessarily the big spikes we saw in winter – again, it’s too early to tell. »

The seasonality of COVID-19 is something scientists are still trying to understand. But one thing is obvious: “This virus is now embedded in our population and our way of life,” Schaffner says.

There are several reassuring factors, says Ko. First, KP.2 is not a very divergent variant – in other words, it does not have a very large number of new mutations that differentiate it from other strains. Second, many people are immune to recent infection with the FLiRT variant’s predecessor, JN.1. Finally, during the summer, people spend less time indoors, reducing the risk of spreading the virus.

“I don’t expect a big increase this summer, but again, we have to be careful and follow the data,” says Ko. “We always have to be humble because SARS-CoV-2 has taught us a lot of new things. »

What are the symptoms of the latest COVID variants?

It is still too early to tell whether the symptoms of KP.2 and other FLiRT variants are different from those of previous strains.

“FLiRT variants are unlikely to create very distinctive symptoms. At the moment it seems to follow the other sub-variants,” explains Schaffner.

Symptoms of FLiRT variants are similar to those caused by JN.1, including:

According to the CDC, the type and severity of symptoms a person experiences generally depends more on their underlying health and immunity than on the variant causing the infection.

Similar to JN.1 and other omicron subvariants, FLiRT variants appear to cause milder infections, Schaffer says.

“There is currently no evidence that leads us to believe that KP.2 is more virulent or more capable of causing severe disease than previous variants,” Ko says.

Do vaccines protect against new variants?

“Early laboratory studies indicate that vaccines will continue to provide protection against KP.2 – somewhat less protection, but by no means zero,” says Schaffner.

As the virus mutates, it gradually becomes different from the omicron strain targeted in the latest updated booster released in fall 2023. “We expect this to happen, and we anticipate that an updated vaccine day will be available in the fall.” to everyone,” Schaffner says.

Even though vaccines don’t prevent infection, they can still provide some protection by preventing severe illness, hospitalizations and complications from COVID-19, TODAY.com previously reported.

“It is still clear that the most serious cases that arrive in the emergency room mainly concern people who are not up to date with their vaccinations or who have not received a vaccine for a very long time,” says Pekosz.

Vaccination is especially important for older adults, Pekosz says, which is why the CDC recently recommended adults ages 65 and older receive an additional dose of the COVID-19 vaccine updated for 2023-2024.

Unfortunately, the vaccination rate is still low, experts note. “Vaccines still show signs of effectiveness, but they are not used at the level they should be,” says Pekosz.

All current PCR and at-home tests recognize KP.2 and other FLiRT variants, experts note. (However, if you have COVID symptoms and test negative, it’s a good idea to stay home to avoid potentially exposing others, TODAY.com previously reported.

If you are using an at-home antigen test, remember to check the expiration date and whether it has been extended by the U.S. Food and Drug Administration.

“Antivirals (like Paxlovid) also work well. … There are no major signs of resistance to antivirals in the population, which is a positive sign,” says Pekosz.

How to protect yourself against new FLiRT variants

Although it is too early to tell how FLiRT variants will develop this summer, people can still take steps to protect themselves and others from COVID-19.

The CDC recommends the following prevention strategies:

• Stay up to date with COVID-19 vaccines.

• Test for COVID-19 if you have symptoms or exposure.

• Stay home when you are sick.

• Resume normal activities only after you no longer have a fever and symptoms have improved for at least 24 hours.

• Practice good hand hygiene.

• Improve ventilation.

• Wear a mask in crowded indoor spaces.

• Practice social distancing.

This article was originally published on TODAY.com