As the holiday season winds down and Covid-19 cases begin to rise, a variant known as JN.1 has emerged as the predominant strain spreading across the United States.
JN.1 originated from the variant BA.2.86 and was first identified in the US in September.
By mid-December, it accounted for 44 percent of Covid cases nationwide, up sharply from about 7 percent in late November, according to data from the Centers for Disease Control and Prevention.
Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center, explained, “Variants take some time to gain momentum.
Then they accelerate, spread widely, and just as they do, after several months, a new variant emerges.”
The current surge in JN.1 indicates that it may be more transmissible or better at evading immune responses compared to other circulating variants.
A C.D.C. report published on December 22 noted that Covid-19 remains “a serious public health threat,” especially for vulnerable populations such as older adults, infants, immunocompromised individuals, and those with chronic medical conditions or who are pregnant.
While JN.1 doesn’t appear to cause severe illness in most cases, even mild infections can lead to significant discomfort for several days, including symptoms like cough, fever, body aches, and fatigue, similar to previous Covid variants.
To protect against infection and severe disease, experts continue to recommend measures such as wearing masks, improving indoor ventilation, staying home when sick, and receiving the latest Covid vaccines.
Research indicates that the updated Covid vaccines released in September generate antibodies effective against JN.1, which is distantly related to the XBB.1.5 variant they were originally designed to target.
Although antibody levels may not be as high against JN.1 as against XBB.1.5, they still reduce the risk of infection.
Dr. David Ho, a virologist at Columbia University, who led research on JN.1 and Covid vaccines, emphasized, “For those recently infected or boosted, there should be decent cross-protection against JN.1 based on our lab studies.”
Rapid tests remain crucial, and according to the C.D.C., existing tests on the market are effective in detecting JN.1.
While Covid cases are showing signs of resurgence, with a 10 percent increase in hospitalizations in mid-December compared to the previous week, hospitalizations remain significantly lower than during previous peaks.
It’s too early to attribute this rise to JN.1 specifically or to increased travel and gatherings during Thanksgiving and the winter holidays.
Dr. Schaffner noted, “When people gather indoors, have parties, and travel, these are circumstances where all respiratory viruses, including JN.1, can spread.”
JN.1 is expected to remain the dominant Covid variant through spring. Experts emphasize the importance of vaccination, particularly for adults over 65, immunocompromised individuals, those with underlying health conditions, and anyone planning to visit vulnerable loved ones.
“Give yourself a New Year’s gift by getting vaccinated if you haven’t already,” urged Dr. Schaffner.
