(Adds details on KP.3 variant, U.S. vaccines)

By Michael Erman

NEW YORK, July 9 (Reuters) - The so-called FLiRT

variants of SARS-CoV-2 coronavirus that cause COVID-19 have been

the dominant forms of the virus circulating this year globally,

according to the World Health Organization

FLiRT is an acronym for the locations of the mutations the

variants share on the virus' spike protein. One of them, called

KP.3, has become the most commonly circulating variant in the

United States over the past month, according to the U.S. Centers

for Disease Control and Prevention.

Here is what you need to know about FLiRT.

HOW ARE FLIRT VARIANTS DIFFERENT FROM PREVIOUS VARIANTS?

The FLiRT variants, which also include KP.3's "parental"

lineage JN.1, have three key mutations on their spike protein

that could help them evade antibodies, according to Johns

Hopkins University.

ARE FLIRT VARIANTS MORE CONTAGIOUS OR LIKELY TO CAUSE MORE

SEVERE ILLNESS?

Dr. Aaron Glatt, chief of infectious diseases at Mount Sinai

South Nassau Hospital in Oceanside, New York, and a spokesperson

for the Infectious Diseases Society of America said in May that

he had not seen evidence of an uptick in disease or

hospitalizations, based on the data he tracks and experience

with his own patients.

"There have been some significant changes in the variants,

but I think in recent times it's not been as important, probably

because of the immunity many, many people already have" from

prior illness and vaccination.

CDC data suggests that COVID-related hospitalizations have

risen slightly since April and the number of patients in

emergency departments who have tested positive for COVID has

increased since May, in line with trends a year ago.

DO CURRENT VACCINES WORK AGAINST THE FLIRT VARIANTS?

The current vaccines should still have some benefit against

the new variants, Glatt said.

Since 2022, health regulators have asked vaccine makers to

design new versions of the COVID-19 vaccines to better target

circulating variants.

Europe's regulator has said vaccine makers should target the

JN.1 variant. U.S. regulators asked for the vaccines to target

variants within the JN.1 lineage, but said the preferred strain

to target would be the KP.2 strain, which was dominant in June.