The JN.1 COVID-19 variant is now the most prevalent strain both globally and in the U.S., where it accounts for an estimated 62% of cases.
Its growth has been rapid, with CDC estimates indicating JN.1 made up about 21% of U.S. cases a month ago.
Officials with the World Health Organization said that globally, nearly 10,000 COVID-19 deaths were reported in December. Compared to November, there was a 42% increase in hospitalizations and a 62% increase in ICU admissions. In the U.S., there was a 20% jump in new admissions for the week ending Dec. 30, when nearly 35,000 people were hospitalized.
"Although COVID-19 is no longer a global health emergency, the virus is still circulating, still changing, and still killing," Tedros Adhanom Ghebreyesus, PhD, WHO director general, said during a Jan. 10 news conference.
Two more updates on the dominant strain:
Disease severity: New findings from a study led by researchers at the Ohio State University indicate BA.2.86 and its close relative, JN.1, may be linked to an increase in disease severity. The research focused on mutations in the spike protein of BA.2.86 and found it can infect human cells that line the lower lung, which is a feature linked to severe symptoms. Researchers emphasized additional research is needed to confirm the findings, since the study used pseudoviruses.
"But from our past experience, we know that infectivity in human epithelial cell lines provides very important information," Shan-Lu Liu, MD, PhD, senior study author and virology professor at OSU, said in a news release. "The concern is whether or not this variant, as well as its descendants including JN.1, will have an increased tendency to infect human lung epithelial cells similar to the parental virus that launched the pandemic in 2020."
In late December, the WHO classified JN.1 as a "variant of interest" due to its rapid spread. At the time, the agency said the overall risk to public health posed by the strain remains low, since updated vaccines continue to offer protection against severe illness. The CDC published its latest update on JN.1 Jan. 5, stating "At this time, there is no evidence JN.1 causes more severe disease."
COVID-19 test results: While at-home tests can detect newer strains including JN.1, more virus samples in the nose may be needed to trigger a positive result, which means accurate results may be delayed, according to experts. If initial results are negative despite symptoms, experts recommend continued testing every day or every other day for up to a week.