More than 30 countries have reported cases of the highly transmissible “U.K. variant” of the novel coronavirus, raising fears of increased global spread of the virus, even as countries begin to unroll vaccination programs in the new year.

Vietnam on Saturday was the latest nation to report a case, which authorities detected in a woman quarantined after recent travel from Britain. Vietnam has banned nearly all international travel, but it is providing repatriation flights for citizens stranded in Britain.

Turkey reported Friday its first 15 cases of the U.K. variant, found in recent travelers from Britain, leading Turkish authorities to issue a temporary ban on entries from there. Turkey, along with many other countries, suspended flights linked with Britain in late December.