A new group of COVID-19 variants was detected in the U.S. in April, and is collectively referred to as “FLiRT”, a combination of the technical terms for their mutations. FLiRT variants are subvariants of Omicron. Existing vaccines and treatments are expected to remain effective strategies to protect against severe illness for these variants based on current information.

It is normal for viruses to mutate over time to form new subvariants, much like how the flu mutates every year requiring an updated flu vaccine. COVID-19 also mutates over time to form different variants and subvariants. By the third week of May, KP.2, a subvariant of the FLiRT lineage, accounted for 28.2% of COVID-19 cases in the US.

Unlike JN.1 (the previously dominant strain in the U.S.), the FLiRT variants have two mutations on their spike proteins. These mutations help the virus evade the body’s current vaccine-induced immunity, which means that these COVID-19 strains may be slightly more contagious than previous strains. However, there has not been an uptick in hospitalizations and COVID-19 cases and there are no new or different symptoms associated with FLiRT subvariants.

It is expected that COVID-19 vaccination still offers protection against severe disease. Last year’s COVID-19 vaccine was based on XBB.1.5 (Omicron XBB), and it has been shown that this vaccine generates some antibodies that are effective against the JN.1 subvariant of Omicron. The new FLiRT variants are subvariants of JN.1. While the vaccine is likely a little less effective against these new subvariants there it is likely to still offer some protection.

The definition of what is considered a COVID-19 wave has changed, and we are seeing lower rates of COVID-19 cases each year (CDC). While it is possible the FLiRT variants will cause an uptick in cases this summer, it would likely still be lower than what was seen in previous years with new variants.

It is still important for people at higher risk of severe COVID-19 infection to take precautions to avoid getting COVID-19. This includes staying up to date on vaccinations and masking in public or crowded indoor spaces. In February, the CDC recommended people over the age of 65 receive a COVID-19 booster.

It is still too soon to know to what extent last year’s COVID-19 vaccine protects against the FLiRT variants, and research is needed to determine this.

Public health officials in the U.S. will decide in June what strain of COVID-19 the updated fall COVID-19 vaccine will be based on. It will likely either be the JN.1 strain or the FLiRT strain depending on which variant remains more dominant.