China will monitor travelers entering the country at some border crossings for signs of infection from a new COVID-19 variant, and will allow local governments to reimpose movement curbs on residents to prevent outbreaks after the country reopens its borders Sunday.

A selected group of cities and harbors have been asked to send test samples of infected travelers for genome sequencing at the National Institute for Viral Disease Control and Prevention, according to an updated COVID-19 control plan released Saturday.

China, which is going through a major wave of infections after dismantling its stringent "zero-COVID" policy in recent weeks, has yet to report any domestic cases of XBB.1.5, a descendant of the omicron XBB subvariant that has now become the dominant strain in the U.S. But health agencies across the world, including the World Health Organization, have raised concern that China isn’t providing enough genome-sequencing information to come to any definitive conclusions.