New Covid FLiRT variants spark concerns of a summer spike

LONDON — New strains of Covid-19 are spreading globally, raising concerns among health professionals about a possible summer spike in cases, four-and-a-half years since the onset of the pandemic.

The FLiRT variants — whose label derives from the names of the mutations in the variants' genetic code — have been rising in the U.S. and Europe as the coronavirus continues to mutate from earlier strains.

The new grouping are descendants of the previously dominant JN.1 variant, an offshoot of omicron. There is currently little evidence that the new strains are more severe, but they appear to have independently picked up the same set of mutations, according to John Hopkins Bloomberg School of Public Health.

KP.2 is now the dominant strain in the U.S., according to the latest data from the Centers for Disease Control and Prevention. The strain accounted for 28.2% of all cases in the two weeks to May 11, up from 3.8% at the end of March, shortly after the strain was first discovered.

Cases of KP.1.1, another FLiRT variant, have also risen to account for 7.1% of current infections, the agency said.

In Europe, too, cases have been rising, with the new variant now detected in 14 countries.

The World Health Organization in its latest update earlier this month said that cases remain limited in all reporting countries. Individual countries, however are showing "slight increases in detections from very low levels."

Last week, the U.K. Health Security Agency said it is continuing to monitor data relating to the new variants in the U.K. and internationally, assessing their severity and the ongoing effectiveness of vaccines. "There is no change to the wider public health advice at this time," the agency said in an update.

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