The new SARS-CoV-2 strain, JN.1, quickly became dominant in the United States, making up nearly half of new COVID-19 infections.
The JN.1 variant now accounts for 44.2% of new infections, according to the Centers for Disease Control and Prevention (CDC) data released on Friday.
The surge in JN.1 cases suggests that the strain is either more transmissible or better at evading the immune system, the CDC said.
However, there is no evidence that the JN.1 variant presents an increased risk to public health than other currently circulating variants.
The CDC expects updated COVID-19 vaccines, tests, and treatments to be as effective against JN.1 as against other currently circulating COVID-19 variants.
A recent study that has not been peer-reviewed found that the updated COVID-19 vaccines offer protection against JN.1, although they may be less effective against the novel variant compared to XBB.1.5.
The World Health Organization (WHO) has recently classified JN.1 as a variant of interest but said the additional public health risks posed by it are low globally.
Fortunately, JN.1 is an Omicron derivative, as most people have been exposed to its variants through vaccination or infection, Marc Johnson, a professor of molecular microbiology and immunology at the University of Missouri School of Medicine, wrote on social network X.
It is fortunate for us that JN.1 is ultimately an Omicron derivative. Our immunity to it is not perfect, but most of us have been exposed to an Omicron lineage previously through vaccination or infection.undefined Marc Johnson (@SolidEvidence) December 23, 2023
A little immunity can be enough to keep you out of the hospital.
"A little immunity can be enough to keep you out of the hospital," he added.
Eric Topol, an executive vice president at Scripps Research Translational Institute, wrote that the surge in JN.1 cases may not result in a spike in hospitalizations, but it adds a significant burden of infections and subsequent risk of long COVID.
The JN.1 variant has taken over in the US. It may not result in a spike of hospitalizations, but it's definitely adding a significant burden of infections and subsequent risk of #LongCovid. Luckily, the XBB.1.5 booster helps protect against JN.1https://t.co/jjl2AnOYb5 pic.twitter.com/ktftJehTeQundefined Eric Topol (@EricTopol) December 22, 2023
What is the JN.1 variant?
JN.1 was first detected in the U.S. in September 2023 and made up less than 0.1% of all SARS-CoV-2 infections by the end of October.
It is closely related to the variant BA.2.86, which the CDC has been tracking since August. The only difference between these two variants is that JN.1 has the additional L455S mutation in the spike protein.
The CDC says symptoms of JN.1 are similar to those of other strains:
- Fever or chills
- Shortness of breath or difficulty breathing
- Muscle or body aches
- New loss of taste or smell
- Sore throat
- Congestion or runny nose
- Nausea or vomiting
Although the JN.1 variant may not increase deaths or hospitalizations, it may drive infection rates and increase the risk of long COVID.