Vietnam reintroduced social distancing measures in the central city of Danang on Sunday after a second locally transmitted novel coronavirus case was detected there, more than three months after any cases were reported in the country.
The Southeast Asian country was back on high alert after the government on Saturday confirmed its first community infection since April, and another case early on Sunday, both in Danang, a tourist hot spot.
Authorities gave no more details about how the two infections were contracted and did not say if they were believed to be linked.
The city's social distancing measures would come into force until further notice, the government said in a statement on its website.
Danang would stop receiving inbound tourists for 14 days, while all religious, sports and cultural events would be suspended.
Wearing masks in public places in the city is now compulsory and gatherings of more than 30 people at public places were banned, the government said.
The detection of the two new cases, which come as Vietnam is seeking to revive its economy and resume international commercial flights, has prompted authorities to step up a crackdown on illegal immigrants.
State media said dozens of migrants from China had been detected in Danang over recent days.
Thanks to strict quarantine measures and an aggressive and widespread testing programme, Vietnam has kept its virus total to an impressively low 418 cases, with no deaths.