Vietnam’s largest metropolis, Ho Chi Minh City, began a strict lockdown in an attempt to curb its worst coronavirus outbreak, a day before US Vice President Kamala Harris arrives in the country on a state visit.

People in high-risk districts are not allowed to leave home under the tight restrictions, which will remain in effect for at least two weeks.

The city said it has mobilised police and army troops to monitor the lockdown and to deliver food as other necessities to each household.

Officials hope to flatten the surge and ease the pressure on the overloaded health care system by asking people to “stay put” and “stay in”.

Since the wave of infections began at the end of April, Vietnam has reported 344,000 cases, with Ho Chi Minh City and neighbouring Binh Duong accounting for most of them.

Ho Chi Minh City and Vietnam’s entire southern region have already been in lockdown since July, when the delta variant started to spread quickly.

Public gatherings are banned, non-essential business are closed and people are asked to only leave home to buy food or for urgent matters.

Since June, Ho Chi Minh City, a metropolis of 10 million people, has set up more than a dozen temporary hospitals to treat Covid-19 patients, but the high number of cases means thousands of patients are not able to be admitted to hospital.

According to the ministry of health, about 19,000 Covid-19 patients with mild symptoms have been asked to stay at home with medical assistance from teams of mobile doctors in their communities.

On Sunday, the health ministry reported 737 deaths, the highest number Vietnam has confirmed in a day, increasing the total death toll to 8,277, mostly in the southern region.

On Tuesday, Ms Harris is to land in Hanoi, which is also under a lockdown, for a two-day visit to boost bilateral relations.

The US has been Vietnam’s largest vaccine donor, providing five million doses of Moderna to help the country’s vaccination programme.