As COVID-19 metrics pick up steam in the U.S, experts are keeping an eye on the growth of a new variant and how it may affect transmission levels in the coming weeks.
Late last month, the World Health Organization elevated BA.2.86 from a variant under monitoring to a variant of interest, clarifying that the overall public health risk posed by the variant and its offshoot, JN.1, remain low.
"It has a growth advantage but this is what we expect from variants that are classified as variants of interest," Maria Van Kerkhove, PhD, the WHO's technical lead for COVID-19, said during a news conference Nov. 29. "In terms of severity, we don't see a change in the disease profile of people infected with BA.2.86 and its sublineages, including JN.1, but it is one, of course, one to watch."
BA.2.86 originally caught experts' attention over the summer because of its large number of mutations in the spike protein. Since then, there's been a "slow but steady increase in the proportion of BA.2.86" reported globally, the WHO said in a risk analysis from late November. Relative to its parent, JN.1 has a single additional change in its spike protein, the L455S mutation, which experts say has some immune-evasion properties worth keeping a close eye on.
Three more notes on JN.1:
- It was first detected in the U.S. in September and has since been identified in 11 other countries. Its parent, BA.2.86, accounted for less than 9% of U.S. cases for the week ending Nov. 25, according to the CDC's variant proportion estimates. JN.1 does not yet appear on the CDC's tracker because it accounts for less than 0.1% of U.S. cases.
- JN.1 appears to be growing relatively quickly in some European countries. Based on its growth there, the U.S. may see dominance "around Christmastime, which means that it would really jump-start a new wave around New Year's," Katelyn Jetelina, PhD, a scientific adviser to the CDC who was involved in developing the agency's wastewater surveillance site, told The Wall Street Journal.
- The CDC said initial data indicates the new COVID-19 shots, which were made to target XBB variants, offer protection against BA.2.86, so experts anticipate similar protection levels against JN.1.