New omicron subvariant may be more likely to infect vaccinated, those who had COVID: NYC officials

Even four doses of mRNA vaccine do not produce high levels of protection against the subvariant, the WHO said.

The omicron subvariant XBB.1.5 may be more likely to infect people who are vaccinated against COVID-19 or who already had the virus, according to the New York City Department of Health and Mental Hygiene.

"Omicron subvariant XBB.1.5 now accounts for 73% of all sequenced COVID-19 cases in NYC. XBB.1.5 is the most transmissible form of COVID-19 that we know of to date and may be more likely to infect people who have been vaccinated or already had COVID-19," the local health agency tweeted Friday.

City officials still said getting vaccinated and boosted is the "best way to protect yourself from hospitalization and death from COVID-19, including from these new variants."

The World Health Organization said last week that "XBB variants are the most antibody-resistant variants to date." Even four doses of an mRNA vaccine combined with previous omicron infection does not produce high levels of protection against the subvariant, the United Nations health agency said.

"There is currently no data on real world vaccine effectiveness against severe disease or death," the WHO said about the XBB variants. The agency is still assessing the subvariants but said "XBB.1.5 does not carry any mutation known to be associated with potential change in severity."