As Americans head into the holidays, there’s a warning about a new COVID-19 mutation that is highly contagious and fast becoming the leading variant in the field. The JN.1 variant now accounts for more than one-fifth of all cases, says USA Today.

The new omicron variant is expected to have similar symptoms and severity as other variants, according to Health. These include more gastrointestinal symptoms such as abdominal pain and diarrhea. Nationally, COVID-19 activity is the highest it’s been so far this year. The risk seems to vary by region, with the Northeast and West seeing lower levels, and the Midwest experiencing its second highest COVID-19 peak ever.

According to the Centers for Disease Control and Prevention, cases involving this mutation make up between 15% and 29% of COVID-19 infections. Experts say it is highly transmissible and better at slipping past people’s immune systems. Hospitalizations and deaths are also on the rise, coinciding with a trajectory of respiratory illnesses that increase in the winter months when people spend more time indoors and visiting friends and family for the holidays.

There is no evidence that that JN.1 causes more serious illness compared with other variants and the latest COVID-19 vaccines and treatments appear to be effective against this mutation. But Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee, says that while JN.1 is likely to dominate for a while, it will be succeeded by other variants down the road.

Schaffner recommends getting vaccinated as soon as possible, before going into malls, traveling, or attending religious services. Be especially careful if you are visiting elderly relatives who may become more ill from COVID-19, or those have chronic conditions, says Schaffner. Mask up in densely populated indoor areas as another layer of protection.