As the holiday season ends and Covid cases rise, a variant called JN.1 has become the most common strain of the virus being transmitted in the United States.
First detected in the country in September last year, JN.1 (which emerged from the BA.2.86 variant) was responsible for 44% of Covid cases in mid-December, well above the approximately 7% recorded at the end of November, according to the CDC (Centers for Disease Control and Prevention), a US government agency.
To some extent, this jump was expected. “Variants take some time to appear,” says Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center. “Then they accelerate, they spread widely, and just when they do that, after a few months, a new variant emerges.”
JN.1’s momentum suggests the variant may be more transmissible or better at evading our immune systems than other circulating strains, according to a CDC report published in December. The agency says that Covid is still “a serious threat to public health”, especially to the population most vulnerable to severe forms of the disease, such as the elderly, children, people with compromised immune systems or chronic medical conditions, as well as pregnant women.
According to experts, JN.1 does not appear to cause severe forms of the disease in most people, although even mild cases can leave a patient “pretty sick for three or four days,” Schaffner said. The symptoms are similar to those caused by previous Covid variants, including cough, fever, body aches and fatigue.
To protect against infection and serious forms of the disease, experts maintain the recommendation to use masks, and advise the population to ventilate closed environments whenever possible, stay at home when sick and take the most recent vaccine against Covid.
A preliminary investigation shows that the updated vaccines, launched in September, produce effective antibodies against JN.1 – the new variant maintains relative similarity to the XBB.1.5 strain, for which the vaccines were developed. Although it does not stimulate the creation of as many antibodies to JN.1, the levels still reduce the risk of the disease.
“For those who are recently infected or boosted, cross-protection against JN.1 should be reasonable, our laboratory studies have shown,” said David Ho, a virologist at Columbia University who led research into the new variant and JN.1 vaccines. Covid, launched in early December. Rapid tests also continue to be a valuable tool, and according to the CDC, products already on the market work well to detect JN.1.
There are signs that Covid cases are rising again. In December, from one week to the next, hospitalizations for the disease increased by 10%, going from 23 thousand to 26 thousand. Even so, the volume of hospitalizations remains well below that recorded during the peak of the first wave of the omicron variant, in January 2022. Compared to the period in which simultaneous cases of Covid, flu and RSV (respiratory syncytial virus) were recorded. , last winter in the northern hemisphere, the volume of infections due to the new variant approached half.
It is still too early to say whether JN.1 is responsible for the increase in hospitalizations or whether this is a reflection of year-end travel and Thanksgiving and winter vacation gatherings.
“When people are gathered close to each other, partying or traveling, they are more prone to transmission. These are situations that favor the circulation of respiratory viruses, including JN.1,” said Schaffner.
The doctor adds seasonality as a common characteristic of Covid. Countries in the northern hemisphere tend to see a lull in cases during the fall, followed by a rise in infections and hospitalizations in the winter.
According to Schaffner, JN.1 will likely remain the dominant version of the coronavirus throughout the spring.
He and other experts noticed that although vaccines offer protection against different variants of the virus, adherence remains low, with only 18% of adults receiving the last doses. Doctors recommend that the entire population should consider getting the vaccine, especially those over 65, immunosuppressed, people with other risk factors related to health conditions and those traveling to meet loved ones who may be vulnerable.
“Give yourself a New Year’s gift by getting this vaccine if you haven’t already,” adds Schaffner.