New York health officials are warning residents that the infectious micron subvariant XBB.1.5 may be more likely to infect people who have already been vaccinated or infected with COVID-19.
“Omicron subvariant XBB.1.5 now accounts for 73% of all COVID-19 cases in New York,” the New York City Department of Health and Mental Hygiene tweeted on Friday. “XBB.1.5 is the most contagious form of COVID-19 that we know of to date and may be more likely to infect people who have been vaccinated against or have previously had COVID-19.”
The department added that vaccination against the virus, including receiving an updated booster vaccine, remains the best way to protect against hospitalization and death, including new variants.
According to data from the Centers for Disease Control and Prevention, XBB.1.5 accounts for 43% of cases in the US.
In the first week of January, the subvariable accounted for about 30% of cases.
XBB.1.5, a fork of XBB, was first spotted in October.
The World Health Organization warned earlier this week that it could lead to an increased number of cases based on genetic characteristics and early estimates of growth rate.
Scientists have warned that the virus will certainly continue to evolve.
“Our concern is how contagious it is,” said Maria Van Kerkhove, WHO’s technical lead for COVID-19.
“The longer this virus circulates, the more likely it is to change,” he noted.
Van Kerkhove said there is no data yet to show that XBB.1.5 causes more severe disease, but that the agency is working on a new risk assessment for the variant that is expected to be released soon.