symptoms, vaccines and what you should know

(CNN) — A new variant of coronavirus has emerged. KP.2, a member of the so-called FliRT variants, nicknamed for their mutations, has become the dominant coronavirus strain in the United States, according to the US Centers for Disease Control and Prevention (CDC). These FliRT variants share certain mutations but are still part of the Omicron family of coronaviruses.

Between April 28 and May 11, nearly 30% of new cases were caused by KP.2, compared with less than 16% in the previous two-week period.

What should people know about this new variant? What are the symptoms of infection? Do vaccines work against the new strain? Are rapid tests reliable? How long should people isolate if they become infected with KP.2? Who should take antiviral drugs if they are infected with this type of Covid-19? And what are the recommendations for people with weakened immune systems? Should they start wearing masks again?

To answer these questions, I spoke with CNN health expert Dr. Leana Wen. Wen is an emergency physician and clinical assistant professor at George Washington University. She previously served as Baltimore’s health commissioner.

CNN: What should people know about this new variant, KP.2?

Dr. Leana Wen: Since the beginning of Covid-19, we have been discussing new options. The original strain of the virus was replaced by the Alpha variant. Then we had Beta, then Delta, and then Omicron.

KP.2 is part of the Omicron family. It appears to be displacing JN.1 and similar subvariants, which were previously the dominant variants in the United States.

Whenever a new variant emerges, three key questions need to be asked: Is it more contagious? Does it cause more serious illness? And do existing vaccines and treatments work in this regard?

One reason a new strain displaces previously dominant ones is because it is just as or more contagious. This means that KP.2 can spread very easily, as we have seen with Covid-19: the coronavirus is extremely contagious and therefore difficult to avoid.

The good news is that KP.2 does not appear to cause more severe disease. In fact, hospitalizations related to Covid-19 are at historic lows. And there is no reason to believe that existing vaccines and treatments will not work against this disease.

CNN: What are the symptoms of KP.2 infection?

Wen: Most people who become infected with the coronavirus will never know which variant is causing their symptoms. Symptoms of Covid-19 infection include runny nose, sore throat, headache, fever, cough and body aches. Some people may experience more severe symptoms, such as difficulty breathing. Covid-19 can also worsen underlying conditions such as heart failure.

None of these symptoms are specific to KP.2, which has so far not been associated with unique symptoms that differentiate it from other coronavirus infections. It’s important to remember that for many people, symptoms of Covid-19 are difficult to distinguish from other viral infections such as flu or colds.

CNN: Are rapid at-home tests still reliable?

Wen: Rapid antigen tests are a simple and convenient method of detecting Covid-19, although they are not as reliable or accurate as laboratory PCR (polymerase chain reaction) tests. There is no indication that home tests are any less effective at detecting this new variant than previous variants.

I encourage people to take a rapid test if they have symptoms and may be eligible for antiviral treatment. If someone is very concerned about having Covid-19, they can take multiple tests on different days and also consider a PCR test.

CNN: Do existing vaccines work against KP.2? What about the vaccine expected to come out in the fall?

Wen: Existing vaccines should still be active against KP.2. The CDC has issued guidance recommending a second shot of the vaccine, which was first released in fall 2023, for people 65 and older.

Federal health officials are expected to recommend a new version of the Covid-19 vaccine in the fall. The new vaccines are expected to be different from current vaccines because the latest vaccines will target variants expected to be in circulation in the fall and winter. If health officials predict KP.2 will be among those variants, fall vaccines will likely be even more effective against KP.2.

CNN: How long should people isolate themselves if they become infected with Covid-19?

Wen: Earlier this year, the CDC lifted the five-day isolation requirement. The agency currently recommends that people diagnosed with Covid-19 stay home until they have had a fever for at least 24 hours and their symptoms have improved. Over the next five days, they should still try to take extra precautions, such as wearing masks and limiting close contact with others.

CNN: Who should get antiviral treatment if they become infected with Covid-19?

Wen: People at high risk of developing severe illness from Covid-19 should consider taking antiviral treatment. This high-risk category includes older adults, people with weakened immune systems, and people with underlying medical conditions.

Two oral drugs are available, as well as a third injectable antiviral drug. I advise everyone to consult with their healthcare provider to determine whether they should take antiviral treatment if they become infected with coronavirus, and if so, which one and how to access it.