FLiRT is currently the dominant COVID-19 variant in several countries, including the US and the UK. Although vaccines are very good at protecting us from severe disease, the virus can still infect a lot of people and cause very unpleasant symptoms. As I’m writing this, my household has just recovered from the disease and I can hear my neighbors coughing just as I did (despite everyone being vaccinated and boosted).

The bottom line is that even if you’re vaccinated, you can still get sick. It won’t be as severe, but you can still get sick. Oh, and if you haven’t been following the variants in the past year, don’t worry — we’ve got you covered.

It’s not clear exactly when FLiRT started to become more dominant because most people aren’t really getting tested anymore, and genomic tests are even rarer. However, in recent months, health agencies like the CDC have been warning about the “FLiRT” subvariants. These are decedents of the Omicron variant JN.1.

This variant is so common in the UK that hospitals are telling visitors with Covid symptoms to stay away, as a summer outbreak seems to be unfolding. So what’s the deal with FLiRT?

The FLiRT variant

Andy Pekosz, PhD, a professor in Molecular Microbiology and Immunology, explained that FLiRT is not a single mutation, but rather several strains.

“This is the term being used to describe a whole family of different variants—including KP.2, JN.1.7, and any other variants starting with KP or JN — that appear to have independently picked up the same set of mutations. This is called convergent evolution. They are all descendants of the JN.1 variant that has been dominant in the U.S. for the past several months.

The particular mutations that people refer to as “FLiRT”s or “FLip”s refer to specific positions in the spike protein — in this case, positions 456, 346, and 572.”

When a virus like SARS-CoV-2 evolves, it is “motivated” to select mutations that bind more strongly to our cells’ receptors and mutations which can avoid neutralizing antibodies. This pressure put on the virus to develop protection from destruction by immune activity is called immune pressure.

Typically, it’s effect on receptor binding and response to immune pressure define whether a mutation is successful or not. The virus’ ability to make effective adjustments in response to these needs is called viral fitness (as per natural selection).

Preliminary findings which are not yet peer reviewed suggest that the FLiRT variants might have traded some binding effectiveness for resistance to immune pressure. In other words, it’s not as infectious, but if you get it, you’re more likely to really feel it. Specifically, people are reporting coughing and hay fever-type symptoms.

“Viruses like SARS-CoV-2 mutate frequently, and when they mutate to evade recognition by antibodies, this often weakens their ability to bind to the cells they want to infect. We then see mutations appear that improve that binding ability. This is a cycle we have seen many times with SARS-CoV-2. The fact that these different variants are picking up the same mutations tells virologists that this combination of mutations is helping the virus accomplish these goals most efficiently.”

This is not the only concerning variant at the moment, however.

From FLiRT to FLuQE

FLuQE became a major variant in New South Wales during the current Australian winter. It’s still early days for FLuQE, but so far, it seems to be FLiRT on steroids. Basically, it’s got all the FLiRT attributes but it’s also better at binding to human cells.

Paul Griffin, an infectious diseases physician and clinical microbiologist at the University of Queensland in Australia, says this what the virus has been doing ever since it came along: it evolves and changes.  

“What this virus has done many times, and continues to do, is that it’s changed significantly,” Griffin told ABC News. Certainly in our country, FLuQE, or KP.3, has passed FLiRT, or KP.2.”

What this all means

We don’t fully understand these new variants but for now, there doesn’t seem to be an immediate risk of things getting out of control. However, Pekosz says, we may still see some outbreak waves.

The FLiRT variants would be high on my list of viruses that could cause another wave of infections in the U.S. That said, our definition of a wave has changed; while we still see case rates rise and fall throughout the year, we see much lower numbers of cases of hospitalizations or deaths than we saw in the first couple years of the pandemic.

“And yet, while these waves are becoming smaller, they are still having the greatest impact on our susceptible populations: the elderly, people who are immunocompromised and those with other secondary medical conditions. Everyone can play a role in protecting those populations that remain the highest-risk when new variants cause an uptick in cases.”

The symptoms are more or less the same as they’ve always been, the vaccines still protect against severe disease, and antivirals like Paxlovid can still be helpful.

It’s also a good idea to keep a few COVID tests around the house. Use one if you see some symptoms like coughing or are feeling something similar to hay fever. If you’re immunocompromised or exhibit severe symptoms, it’s always a good idea to consult your doctor.

“If you do feel sick, follow the CDC’s simplified guidance for respiratory illnesses. This is especially important if you plan to spend time with friends or family who are at higher risk of severe illness,” concludes Pekosz.