A growing COVID-19 variant has taken off this holiday season...

Scientists are narrowing in on the fastest-growing COVID-19 variant, learning more about the strain

that has coincided with a rise in cases as Americans head into the holidays.

The JN.1 variant now accounts for more than one-fifth of all cases, based on estimates Friday from the Centers for Disease Control and Prevention. In the CDC's latest Nowcast reporting period, cases involving this mutation make up between 15% and 29% of COVID infections. The variant previously accounted for an estimated 8% of cases.

This uptick suggests that JN.1 could be more transmissible and better at slipping past people’s immune systems, the CDC said. Hospitalizations and deaths, indicators for COVID-19 spread, also remain elevated, with cases rising in the Midwest and Mid-Atlantic. This follows a pattern of respiratory illnesses increasing in winter months with people indoors and visiting friends and family for the holidays. 

“The narrative here is that JN.1 may be somewhat more contagious," Dr. Rebecca Wurtz, a professor at the University of Minnesota School of Public Health, told USA TODAY. "Thanksgiving happened, winter is starting to happen, and that’s probably what caused it to jump like it did."

The COVID-19 virus is constantly mutating, like any virus, and is bound to create more variants to survive. JN.1 was first detected in the U.S. in September. It had previously been classified with BA.2.86, or Pirola, a descendant of the omicron family, which some researchers early on worried could pose risks, but cases have recently declined in CDC estimates. In contrast, the original omicron variant overwhelmed hospital systems in 2022.

So far, it appears JN.1 doesn’t present a greater risk. Vaccination and previous infection also appear to help reduce the risk of serious illness from JN.1.

Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center, in Nashville, Tennessee, likened JN.1 and other subvariants to children and grandchildren of omicron.

“It’s likely to continue to dominate,” Schaffner said. “We anticipate it will be succeeded by other grandchildren, variants, down the road.” (USA TODAY)