Two new subvariants of COVID-19, collectively dubbed FLiRT, are increasingly outpacing the dominant winter strain, in anticipation of a possible summer surge in coronavirus infections.
The new FLiRT subvariants, officially known as KP.2 and KP.1.1, are believed to be about 20% more transmissible than their parent, JN.1, the dominant winter subvariant, Dr Peter said Chin-Hong, infectious disease expert. at UC San Francisco.
The two FLiRT subvariants combined accounted for about 35% of coronavirus infections nationwide for the two-week period beginning April 28, according to the U.S. Centers for Disease Control and Prevention. On the other hand, it is now estimated that JN.1 represents 16% of infections; by mid-winter, it was over 80%.
“It’s been quite a while since we’ve had a new dominant variant in the United States,” said Dr. David Bronstein, an infectious disease specialist at Kaiser Permanente Southern California. “With each of these variants following the previous one, we see increased transmissibility – it’s easier to spread from person to person. So that’s really FLiRT’s problem.
The largest FLiRT subvariant, KP.2, is growing particularly rapidly as a proportion of existing coronavirus infections. At the end of March, it represented only 4% of estimated infections nationally; more recently it is estimated to represent 28.2%.
The new sub-variants have been named FLiRT for mutations of the evolved COVID-19 virus. “So instead of an “L,” there’s an “F.” And instead of a “T”, there is an “R”. And then they put an ‘i’ to make it cute,” Chin-Hong said.
Despite their increased transmissibility, the new mutations do not appear to lead to more severe disease. And the vaccine should continue to work well, given that the new subvariants differ only slightly from the winter version.
The entry of subvariants also comes as COVID-19 hospitalizations reach record levels. For the week ending April 27, there were 5,098 admissions, a seventh of this winter’s peak, when 35,137 admissions were reported for the week ending January 6.
However, as of May 1, hospitals nationwide are no longer required to report COVID-19-related admissions to the U.S. Department of Health and Human Services; only data submitted voluntarily will now be published nationally.
In Los Angeles County, COVID-19 levels appear to be in a lull. For the week ending April 27, coronavirus levels in LA County wastewater were 8% of the winter peak.
Still, some doctors say they wouldn’t be surprised if there was a summer surge in COVID cases — as has happened in previous seasons.
“By summer, we can expect people’s immunity to be a little lower,” Chin-Hong said. For those who are older or immunocompromised, “they are potentially at risk for more severe disease.”
Additionally, people often gather indoors during the summer to avoid the heat, which can increase the risk of transmission in crowded public places.
Chin-Hong said he was seeing COVID-19 patients at UC San Francisco with severe illness, and “they were either very old or very immunocompromised and they didn’t get the most common vaccines.” more recent”.
Doctors say the fact that FLiRT subvariants spread more easily highlights how important it is for those most at risk to be up to date on their vaccinations and stay away from sick people.
And while the risk of long COVID is likely lower than at the start of the pandemic, it still exists.
Many people have not received a recent COVID-19 vaccine, data shows. For the week ending Feb. 24, 29% of the nation’s seniors received a dose of the updated vaccine, available in September. In California, as of April 30, about 36% of seniors had received an updated dose.
“We’re still seeing these hospitalizations and poor outcomes, and even people dying from COVID. It hasn’t gone away,” Bronstein said. “The good news is that the vaccine … is still very effective in protecting you against hospitalizations, serious outcomes and death.”
Between October and April, more than 42,000 COVID-19 deaths were recorded nationwide, according to the CDC. This is significantly more than the estimated number of deaths due to influenza over the same period: 24,000.
This number, however, is lower than the comparable period of the previous season, when more than 70,000 COVID deaths were reported. And this figure is much lower than that of the first two devastating pandemic winters: between October 2021 and April 2022, more than 272,000 deaths were recorded; and between October 2020 and April 2021, this number was over 370,000.
In February, the CDC recommended that people ages 65 and older receive a second dose of the updated vaccine provided at least four months have passed since a previous shot. The CDC also says everyone 6 months and older should receive one dose of the updated vaccine.
“Right now, the most important thing people can do is get vaccinated,” Bronstein said. He suggested that those who are particularly vulnerable continue to wear a mask whenever possible, especially in places like crowded airports and planes.
Additionally, he added, it is important for sick people to stay home to avoid spreading germs to others, especially the elderly. And if sick people must leave their homes, they must wear a mask in the presence of others.
“Even in the summer, what may seem like a cold may actually be a COVID infection,” Bronstein said. “We need to make sure that if you are sick, get tested as much as possible, stay home…and make sure your symptoms are milder before you decide to return to your usual activities.”
California recommends that people with COVID-19 symptoms stay home until symptoms are mild and improving and they have been fever-free for 24 hours without medication.
They must also wear a mask around others when indoors for 10 days after becoming ill or, if they have no symptoms, after testing positive. They can stop wearing a mask early if they get two consecutive negative rapid test results at least one day apart. But they should avoid contact with anyone at high risk for 10 days, according to the state Department of Public Health.
And before travel plans this summer, Chin-Hong suggested that seniors talk with their health care provider to ensure that, if they contract COVID-19, Paxlovid can be prescribed without interfering with others. drugs. Paxlovid is an antiviral medicine that, when taken by people at risk of severe COVID-19 with mild to moderate illness, reduces the risk of hospitalization and death.
Chin-Hong also suggests that it makes sense for health care providers to prescribe Paxlovid to higher-risk people who plan to travel to places where the drug may not be readily available, as a “just-in-time” prescription. case where”. Clinicians have this discretion since Paxlovid has been fully approved by the U.S. Food and Drug Administration, giving health care providers greater latitude in deciding when to prescribe the drug.
Earlier this year, another drug was also made available to help protect the most vulnerable, such as cancer patients and those who have received an organ transplant. This is a monoclonal antibody called Pemgarda, which is administered intravenously and can be given once every three months. Authorized by the FDA for emergency use, it is administered prophylactically and may help recipients prevent COVID-19 if they are subsequently exposed to an infected person.
A new version of the COVID-19 vaccine is also expected to be available by September. It could be designed against last winter’s JN.1 strain, but it’s also possible that officials decide it should be designed against the growing FLiRT subvariants, Chin-Hong said.
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