GBN Health Check: What are the FLiRT Covid variants and how worried should you be about a summer wave?

Professor Steve Griffin of Leeds University recently said: “This is clearly early days, but it certainly looks as though yet another Covid wave is building. If the rise in hospitalisations continues, this is obviously worrying."

His fears are not unfounded: hospital admissions rose by 24 percent in the week ending June 16 - climbing to 3.31 per 100,000 from 2.67 the previous week, UKHSA data shows.

The number of people hospitalised was highest among the elderly, peaking at 34.70 in the over-85s.

There was also a 29 percent surge in positive cases in the week to June 22, although the majority of testing is now done in hospital and healthcare settings so this may be skewing the figures somewhat.

The upswing is being attributed to a new group of COVID-19 variants, known collectively as FLiRT, which are thought to have emerged sometime in early April.

The 'FLiRT' designation was inspired by the names of the mutations in the genetic code of the variants, however, a spokesperson for the UK Health Security Agency takes umbrage with the moniker, telling your correspondent that the nickname was made by "speculators and media voices" - not scientists.

The FLiRT family includes the strains KP.1, K.P2 and K.P3. They descend from JN.1 - a variant which emerged at the end of 2023 and accounted for around 60 percent of cases in England at the start of this year, UKHSA data shows.

It soon became apparent that the three strains had a growth advantage over JN.1; accounting for 40 percent of all cases in the UK as of April 2024.

However, KP.2 pulled away from the pack in May before passing the baton to KP.3, which has almost doubled UK infections in less than two weeks.

KP.3 has also superseded the other strains across the pond. Based on current surveillance data and model projections, KP.3 is estimated to account for a third of current COVID-19 cases in the US.

How worried should you be?

The numbers are on a "slight upward trend" but a summer wave is unlikely as we are starting from a "pretty low base", a UKHSA spokesman tells GB News.

Unlike previous waves, testing is much more limited so there's a lot of "noise" in the data, he says.

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Although KP.3 and the other FLiRT strains appear to have a "small growth advantage" over JN.1, this is not translating into increased severity and hospitalisations, the UKHSA spokesman says.

He acknowledges that it's difficult to compare the severity and immune escape transmissibility of variants today with earlier waves because the situation is now markedly different thanks to both natural and vaccine-induced immunity.

But the main takeaway is that no single variant is taking over in a "big way". The infectious disease expert says there's much more fragmentation nowadays, with multiple variants vying for supremacy.

This is a far cry from the days of Delta, which accounted for 90 percent of all cases within a couple of months of bursting onto the scene, the UKHSA spokesman adds.

Not out of the woods yet

Not everyone is so sanguine. The KP.3 variant has a couple of mutations on the spike protein - the route by which the virus gains entry into healthy cells - that are "unusual" and concerning, notes Doctor Daniel Rhoads, Head of Microbiology at the Cleveland Clinic.

As Doctor Rhoads, who also serves as the Vice Chair of the Microbiology Committee, explains, the evolution of the shape of the spike protein which occurs through mutations is thought to balance the virus’ fitness (its ability to infect humans and replicate) with its immune escape properties (its ability to evade humans’ immune memory, such as antibodies formed due to vaccines or previous infection).

KP.3 is "winning" compared to other variants at this time because it has found a "sweet spot" in the combination of fitness and immune escape, he warns.

Preliminary research backs this up. A paper published by Japanese scientists last month, which was released as a preprint that has not yet been peer-reviewed, revealed that some of the mutations to the KP.3 variant's spike protein indicate it could be more infectious than JN. 1. and have "increased immune evasion".

The researchers conclude that KP.3 could increase the effective reproduction number, or Re - this is the number of people in a population who can be infected by an individual at any specific time.

Although, enhanced transmissibility does not necessarily mean it is more harmful.

As Doctor Rhoads points out, there is "no clear evidence" that KP.3 causes more severe illness than other strains.

For most people, the worst-case scenario is cold-like symptoms, such as:

• Fever
• Cough
• Fatigue
• Loss of taste or smell

Stopping the spread 

Current Government guidance advises those who test positive for Covid to self-isolate for five days and to steer clear of high-risk individuals, including the elderly and immunocompromised, to prevent serious illness transmission.

The UKHSA has issued similar advice: "If you are showing symptoms of Covid-19 or flu, help protect others by staying at home and avoiding contact with other people, especially those who are more vulnerable."

Doctor Rhoads also makes the point that "we have been living with COVID-19 for more than four years now" so we have a pretty good defensive arsenal by now.

"Use vaccines and good hygiene tools available to us to prevent the spread of COVID-19 and other infections caused by respiratory viruses," he advised.

Likewise, Doctor Mary Rodgers, Associate Research Fellow and infectious disease expert at Abbott, tells GB News that there is no indication that tests or treatments are less effective for these new strains.

Studies have consistently shown that vaccination offers the best protection against Covid. And promising new vaccines are in the pipeline.

Researchers have developed a new vaccine technology that's been shown in mice to protect against a broad range of coronaviruses with the potential for future disease outbreaks - including ones we don’t even know about.

Although getting needles into arms is proving to be increasingly challenging.

“Although we’ve just had a spring booster campaign for vulnerable populations, the uptake was lower than in 2023. There is a considerable difference between the current vaccines and circulating viruses," lamented Professor Griffin of Leeds University.

Around 4.1 million of the seven million eligible for a spring Covid booster took up the offer, meaning 40 percent of those called up will not get the extra protection despite being deemed most vulnerable. More than a third of care home residents have not had a booster either.

This trend is concerning as Covid is here to stay.

Or, as the spokesman for UKHSA puts it, "mutations that confer a survival and reproduction advantage are the ones that will survive", which begs the question: what if KP.3 is a dress rehearsal for something far worse?