HANOI, Vietnam — Vietnam’s airlines will resume domestic flights on Sunday, after the country suspended their operation in July to contain the spread of the coronavirus.

In the first phase of the resumption, passengers must be vaccinated with at least one shot and hold a negative virus test to board flights, according to the plan announced by the civil aviation authority Thursday. Carriers can board only half of each plane’s seat capacity.

Noi Bai airport in Hanoi, Vietnam’s major city in the northern region, will remain closed for domestic flights. The city authority said on Wednesday it was not ready to receive a large volume of travelers, who could potentially spread the virus.

The outbreak fueled by the delta variant that began in July was Vietnam’s worst, infecting over 800,000 people and killing more than 20,000. More than half of the 98 million population was under lockdown for almost three months.