A Member of Newer Family of ‘FLiRT’ COVID-19 Variants is Dominant Strain In United States


According to the latest Centers for Disease Control and Prevention (CDC) data, these strains have increased in incidence rates, and now account for nearly a third of all US cases.

CDC logo

Data trends show a new family of variants has arisen, but that hospitalizations and deaths have decreased.

CDC is reporting the KP2 variant is the dominant strain of COVID-19 in terms of cases being reported in the United States, with 25% of all current infections from it.1 This comes from the federal agency’s latest reporting week, April 21-27, 2024.

KP2 is included in a newer family of variants, called “FLiRTs,” named after their mutations.2 According to CDC, another FLiRT variant, KP11, accounts for about 7.5% of cases. Together, they account for 32.5% of all reported cases in the country.1

Additionally, the JN1 strain, which was formerly the dominant strain in the United States is now shown to be 22% of all US cases.1

These newer “FLiRT” variants have been so named based on the technical names for their mutations, one of which includes the letters “F” and “L,” and another of which includes the letters “R” and “T.” 3

table of variant proportions

Table 1. Here is a summary of the variants, reporting the week of April 21-27, 2024.

Table credit: ChatGPT

Hospitalization and Mortality Rates
CDC’s data does show some positive news in that both hospitalizations and deaths have been trending down. For the reporting week of April 21-27, 2024, there was a total of 727 new hospital admissions of patients confirmed with COVID-19 in all age groups. This is down from the 819 hospitalizations the week before (April 14-April 20.)

In terms of mortality in the US, there were 184 provisional COVID-19 deaths for the week, ending April 27. This is a continuing downward trend from the previous 2 weeks where there was 347 deaths the week ending April 20, and the week before that (week ending April 13), there were 485 deaths.

table of deaths and hospitilzations

Table 2. This summarizes the COVID-19 hospitalizations and mortality rates in recent weeks.

Table credit: CHATGPT

Changes in Data Reporting
According to CDC, it is important to note that as of May 1, 2024, hospitals were no longer required to report COVID-19 hospital admissions, hospital capacity, or hospital occupancy data to Health and Human Services, through CDC’s National Healthcare Safety Network (NHSN). Thus the data going forward could be limited, especially as medical institutions are not obligated to report data.

However, the CDC says it still encourages ongoing, voluntary reporting of hospitalization data. The data voluntarily reported to NHSN after May 1, will be available starting May 10.


1.COVID Data Tracker.CDC. Accessed May 6, 2024.

2. Novak S. New ‘FLiRT’ Variants Spark Summer COVID Surge Warning. WebMD. April 30, 2024. Accessed May 6. 2024. https://www.webmd.com/covid/news/20240430/new-variant-sparks-summer-covid-surge-warning
3. Ducharme J. What to Know About the ‘FLiRT’ Variants of COVID-19. Time. April 29, 2024. Accessed May 6. 2024. https://time.com/6972143/covid-19-flirt-variants-kp-2/

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