Explained: New Covid-19 variants FLiRT and LB.1, driving surge in US, UK

What impact could these mutations have and what precautions should be taken? We explain.

What do we know about the new variants, FLiRT and LB.1?

FLiRT is a group of variants which include KP.2, JN.1.7, and any other variants starting with KP or JN. They are descendants of the JN.1 variant, which dominated infections in the US during late 2023 and early 2024.

Its symptoms resemble those of earlier variants, including fever, cough, fatigue and digestive issues with a heightened transmission rate. Of concern is its ability to evade immunity, gained from vaccines and previous infections.

The LB.1 strain, a mutation of the FLiRT group, was responsible for 17.5% of Covid-19 cases in the US this year as summer began. Both FLiRT and LB.1 are highly transmissible.

Preliminary research data from the Infectious Diseases Society of America shows most common FLiRT variants are mutations which can infect people who are vaccinated. They spread more easily than JN.1, while LB.1 is poised to be more infectious and transmissible than its predecessors.

Should we be concerned?

The uptick in cases has been chiefly reported from the US, the United Kingdom and Singapore, with an increased rate of hospitalisation. CDC data for June 16 to 22 showed that the number of emergency room visits had increased to over 23%, while Covid-19 deaths had also risen by 14.3% in recent weeks. However, the share of Covid-19 deaths as a part of all deaths remains low, at 0.8%.

The Singapore Ministry of Health reported that the number of Covid-19 cases had risen to 25,900 cases between May 5 to 11 over the previous week’s 13,700 cases, while the number hospitalised increased from 181 to 250 over the same period.

The Indian Express in May reported that 290 cases of the KP.2 variant and 34 cases of the KP.1 variant had been detected in India.

Has Covid resurfaced?

Ever since Covid-19 began circulation in late 2019, the virus has continued to exist in and around humans. What has changed is how humans gradually acquired immunity to it compared to when it first appeared.

The US removed its mask mandates in early 2022, while the CDC stopped reporting daily case numbers on its data tracker by May 2023, viewing the situation as no longer being a public health emergency. There are also fewer tests being done for it, resulting in lower reporting of numbers.

However, Covid-19 strains continue to mutate and evolve. Over time, the immunity against the virus, developed through infections and vaccines, starts wearing off. Paul Hunter, a professor of medicine at the University of East Anglia in the UK, told Deutsche Welle: “Sterilizing immunity following an infection or vaccination only lasts four to six months on average, so immunity gained from infections during winter or the autumn vaccination campaign will have already been lost for the most part.”

This results in the need for continued booster doses of the vaccine. The US Food and Drug Administration (FDA) has appealed to drug manufacturers to target the new variant as well. In particular, the elderly and those with comorbidities are more vulnerable to the infection.

How can one prevent infection?

Preventative measures prescribed since the beginning of the pandemic in 2020 should be adhered to, including maintaining social distancing, using well-fitted respiratory masks like N95 or KN95 indoors to protect against all variants, and increasing ventilation while indoors.

People vulnerable to the infection on account of their comorbidities, as well as those in areas where the spread of the infection has been reported, are advised to take extra precautions. Booster doses against the vaccine can help provide immunity against the current strain.