COVID ‘FLiRT’ Variants Are Spreading–Here’s What to Know

A new family of COVID-19 variants known as ‘FLiRT’ is now dominant in the United States. The most effective solution may be to strengthen our natural immunity.

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A new family of COVID-19 variants, known as “FLiRT,” is now dominant in the United States.

The name comes from its mutation. It contains two new key mutations compared to the previous dominant variant JN.1. One mutation is “F456L,” representing an amino acid code change from “F” to “L” at the 456th amino acid of the spike protein chain. The other, “R346T,” represents the amino acid code change from “R” to “T” at position 346.

These mutations are responsible for the behavior of the new variants.

Rose to the Dominant Variant in 2 Months

According to the U.S. Centers for Disease Control and Prevention (CDC), one out of three COVID-19 cases in the United States currently has this new variant.

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FLiRT includes KP.2, KP.1.1, KS.1, and JN.1.16.1. The two most important “FLiRT” family members are KP.2 and KP.1.1.

KP.2 rose from 1.4 percent to 28.2 percent of all COVID-19 circulating variants from March to May. This surge occurred as quickly as did JN.1, which replaced EG.5 from October to December 2023.

KP.1.1 is less prevalent, accounting for 7.1 percent of all cases in the United States. Together with KP.2, FLiRT currently accounts for 35.3 percent, or more than a third of new cases.

A new COVID variant, FLiRT, is quickly spreading in the United States. Source: CDC

In India, KP.2 accounted for 30 percent of all COVID-19 cases, according to the latest update in May.

The May 1 WHO report listed KP.2 as a variant under close watch.

Slightly More Infectious

According to a recent research preprint, the binding affinity of KP.2—which indicates how fast a new variant can infect people—increased by 1.2 times compared to that of the JN.1 variant.

Researchers used a binding affinity test that involves putting the angiotensin-converting enzyme 2 (ACE2) receptor (where the virus binds and invades the human cells) and variants into a system similar to a test tube. This type of test is fast, simple, and easy to control, while its weakness is that it does not represent the entire picture of what happens in the human body.

This data suggests a slightly higher infectivity rate for KP.2, which seems incompatible with the rate at which it is currently spreading. This indicates that there must be other reasons for the fast spread of the virus.

When assessing a variant’s infectivity and its ability to spread quickly in a population, there are many more proteins, molecules, and factors inside our human bodies that need to be considered.

‘Antibody’ Escape

While most media use the term “immune escape,” we would prefer to use the term “antibody escape’ because it is more accurate. Here is why.

When a virus invades our body, our immune system has various methods of fighting the invader. One of the most extensively researched ways is by producing antibodies.

Antibodies are protective proteins that our immune cells produce to clear viruses and other disease-causing foreign substances called antigens.

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The preprint study suggests that neither a prior infection nor the latest booster based on the Omicron XBB variant, provide expected  protection against FLiRT.

Scientists studied five groups of people reinfected with COVID-19 by different combinations of Omicron variants. They tested the neutralizing ability of the antibodies in their blood with different variants. Three of the five groups had a history of vaccination.

The results showed a 1.5- to 1.9-fold reduction in the levels of neutralizing antibodies in response to FLiRT variants, compared with JN.1. This meant that people would not gain adequate protection against FLiRT from a previous COVID-19 infection or vaccination.

Other close relatives of FLiRT show a similar trend. Specifically, one subvariant called KP.3 was the strongest at escaping the immune system, with a 1.9- to 2.4-fold reduction in neutralizing antibodies, compared to JN.1.

Lock and Key

Since Omicron appeared, keeping up with the rate of constantly mutating variants has been difficult for the development of boosters.

Two major mutations in FLiRT, F456L and R346T, are located near the receptor-binding parts known to be related to antibody escape.

The interaction between the ACE2 receptor and the SARS-CoV-2 virus is like a key being inserted into a lock to gain entry into the cell. The virus mutants alter the shape of the parts of the “key” in contact with the receptor, making it easier to open the “lock.” This increase in binding affinity allows the virus to enter the cell and infect people more easily.

Meanwhile, the change in the key’s critical parts also impacts the antibody’s ability to bind and clear them. This is why vaccine efficacy could decrease.

Since the JN.1 era, the virus has gained additional tricks—including the “FLip” mutation (F456L + L455F) and non-spike protein mutations—to further weaken the antibody’s neutralization effects and escape from established immunity. As a descendant of the JN.1 family, FLiRT has inherited the same features.

Our Natural Immune Defense

Some people are worried about an upcoming summer wave linked to FLiRT, and others have suggested making another type of booster vaccine based on the new JN.1 variant.

This seems logical, as research has shown that natural and vaccine-induced immunity fades. However, changing the vaccine design may not be possible each time the virus changes its gene code.

Does our immunity to the virus simply depend on antibodies or do we have other effective ways to fight?

Our immunity isn’t lost when antibody escape occurs. It’s just one part of our immune system that’s weakened.

Our body has many powerful weapons against viruses, and antibodies are not the only tool we have. Children who cannot produce antibodies have demonstrated an ability to fully recover from viral infections like measles.

Our natural immunity can effectively fight a virus, regardless of how a variant mutates.

For example, when a virus invades the body, it triggers a defense mechanism involving interferon.

Interferon is a key antiviral protein that is secreted by the epithelial cells when a virus attaches. It activates an antiviral state, orchestrating pivotal downstream antiviral mechanisms.

Two recent articles published in Nature and Science have revealed that older adults produce fewer interferons, which explains why severe cases are most likely seen in this age group when infected with a virus.

The way we think can also impact our interferon production. People with a compassionate mindset have demonstrated a higher level of interferon. As we grow older, we often become more empathetic and considerate of others. The health benefits that come with these positive changes can potentially counteract the negative effects of aging.

Furthermore, recent scientific research has uncovered new immune defenses that were previously unknown.

Interferon triggers a range of specialized weapons to fight infections. One of these weapons, called guanylate-binding protein (GBP), operates as a vigilant guard against various invaders, including viruses and germs.

John MacMicking, a professor of microbial pathogenesis and immunobiology at Yale School of Medicine, recently described GBP1 as a “giant nanomachine” that could trap invading bacteria and viral intruders in our body.

When a germ enters the body, our immune cells release GBP1 proteins. These proteins act like sticky ropes and wrap around the germ, creating a net that traps it. Within a short period, the bacterium becomes surrounded by an inescapable straitjacket. As many as 30,000 GBP1 proteins can enclose the pathogen, effectively trapping it in a kind of body bag.

GBP1 plays a crucial role in antiviral defense against many viruses, including vesicular stomatitis virus, encephalomyocarditis virus, and dengue virus.

How many other powerful weapons does our body possess that we are not yet aware of?

Our miraculous innate ability to heal and fight off infections is a powerful tool we must not overlook. By focusing on safeguarding our natural immunity and healing power through a healthy lifestyle, we can reduce concerns about the FLiRT variant.

Views expressed in this article are the opinions of the author and do not necessarily reflect the views of The Epoch Times. Epoch Health welcomes professional discussion and friendly debate. To submit an opinion piece, please follow these guidelines and submit through our form here.