Nimbus variant spreads across the US

In January, a new COVID-19 variant NB.1.8.1 or Nimbus was first detected in China, and since then, it has been detected in 22 countries, including the United States.

On May 23, the World Health Organization (WHO) designated NB.1.8.1 as a variant under monitoring after cases grew rapidly in prevalence worldwide, going from 2.5% to 10.7% in four weeks.

In the United States, NB.1.8.1 was first detected in late March and early April among international travelers who arrived at airports in California, Washington, Virginia, and New York City. For the period ending June 7, NB.1.8.1 made up around 37% of the country's COVID-19 samples, up from 15% during the previous two-week period. NB.1.8.1 now makes up roughly the same number of cases as the LP.8.1 variant, which has been dominant in the United States over the last few months.

"Data indicates that NB.1.8.1 does not lead to more severe illness compared to previous variants, although it appears to have a growth advantage, suggesting it may spread more easily," said Subhash Verma, a professor of microbiology and immunology at the University of Nevada, Reno School of Medicine. "In other words, it is more transmissible."

According to Verma, symptoms from the NB.1.8.1 variant have been largely like earlier variants, including cough, sore throat, fever, and fatigue. Some patients have also reported experiencing "razor blade throat," where it feels like their throats are covered with razor blades.

Are COVID-19 vaccines still effective against Nimbus?

According to WHO, currently approved COVID-19 vaccines are expected to still be effective against NB.1.8.1. Health experts have also recommended that individuals who have a higher risk of severe COVID-19 get vaccinated if they haven't already.

"Those in high-risk groups should consider getting the vaccine now if they haven't been vaccinated in the last six months and consider receiving an updated vaccine for the upcoming winter season," said Albert Ko, a professor of public health, epidemiology, and medicine at the Yale School of Public Health.

However, it may be more difficult for people to access updated COVID-19 vaccines, which will target the LP.8.1 variant, when they're released in the fall. Last month, FDA announced that it would limit future access to COVID-19 vaccines to people ages 65 and older or those with a high risk of COVID-19 complications. Drug manufacturers are also required to conduct clinical trials of their COVID-19 vaccines before they can be approved.

The requirement for new studies on vaccines "that have already demonstrated reduction in symptomatic disease and are only being updated based on new strains is ill-advised. These studies are expensive and will take time," said Anna Durbin, director of the Center for Immunization Research at the Johns Hopkins Bloomberg School of Public Health. "If vaccines are updated annually, then the results will not be ready in sufficient time for people to use the vaccines."

Separately, HHS Secretary Robert F. Kennedy Jr. recently announced that CDC would no longer recommend routine COVID-19 vaccines for healthy children and pregnant women — a decision that many health organizations and experts criticized.

In an open letter, 30 healthcare organizations, including the American Medical Association, wrote that "we must continue to prioritize high levels of COVID-19 vaccine coverage in pregnant patients to protect them and their infants after birth."

Overall, "I'm concerned about accessibility," said Rajendram Rajnarayanan, from the New York Institute of Technology campus in Arkansas. He added that it's not clear if vaccines that aren't included in federal recommendation will be available to people without insurance. "These kinds of things are still murky and I really want to see clearer guidelines."