COVID Variant KP.3 Surges to Dominance—Here's What You Need to Know

A new COVID-19 variant called KP.3 has surged to dominance in the United States, according to recent data from the Centers for Disease Control and Prevention (CDC). 

As of June 8, KP.3 accounted for 25% of cases, per the CDC. The variant has surpassed the previous dominant variant, KP.2, which now makes up about 22% of cases. Both have knocked down JN.1, the top strain circulating this past winter.

With SARS-CoV-2, the virus that causes COVID, mutating consistently, it’s natural to be concerned each time a new variant rises to prominence. 

Here’s what you need to know about KP.3, including whether experts are worried about its speedy spread.

What Is KP.3?

KP.3 is part of a newly identified group of variants dubbed “FLiRT,” which are part of SARS-CoV-2’s Omicron lineage. In addition to KP.3, the FLiRT variants also include KP.2 and KP.1.1. They all descend from JN.1.

KP.3 is similar to JN.1 in its structure except for two changes in the spike protein, Carlos Zambrano, MD, a board-certified infectious disease physician and the head of the COVID-19 Task Force at Loretto Hospital in Chicago, told Health.

The spike protein is located on the virus’s surface and facilitates its entry into human cells.

“One change was observed in the XBB.1.5 lineage, which was predominant in 2023,” he said. “The second change was observed in viruses circulating in 2021.”

Why Is KP.3 Involved in So Many Cases?

According to C. Leilani Valdes, MD, a pathologist and medical director at Regional Pathology Associates in Victoria, Texas, the KP.3 variant has become the frontrunner because it spreads quickly and easily. 

It is “very good at jumping from one person to another,” she said. “This means more people are getting infected with KP.3 compared to other variants.”

Does KP.3 Cause More Severe Illness Than Other COVID Strains?

Both experts agreed that there is currently no clear evidence that KP.3 causes more severe illness than other strains, including the JN.1 strain or its derivatives. As such, people who contract KP.3 can expect to experience symptoms characteristic of other recent COVID variants.

“KP.3 symptoms resemble typical COVID-19 symptoms, including fever, cough, fatigue, and loss of taste or smell,” Valdes said. “Some individuals may also experience a sore throat, headache, or muscle pain.”

Are COVID Cases Rising?

“COVID cases are on the rise, and we can expect the number of cases to continue to increase, especially with the KP.3 variant spreading quickly,” Valdes said. 

The CDC reported last week that COVID-19 infections are “growing or likely growing in 30 states and territories.” Cases are “stable or uncertain” in 18 others and are likely declining in one—Oklahoma.

Do Vaccines Protect Against KP.3?

Per Zambrano, all three COVID vaccine manufacturers—Pfizer, Moderna, and Novavax—have said that their new vaccines slated for August 2024 will target the JN.1 variant.

Because the JN.1 variant is closely related to the FLiRT variants, experts have said that matching the vaccines to JN.1 will offer better protection.

Valdes stressed that vaccination remains “one of the most effective tools” against COVID. “Staying up to date with booster shots significantly reduces the risk of severe illness and hospitalization,” she said. “Wearing masks, washing hands, and keeping distance from others can help prevent the spread.”

“The most important takeaway as we head into the summer is that KP.3 spreads easily,” she added, “so it’s important to be careful.”