The central city, caught in a fresh Covid-19 outbreak that has hospitalized two residents in critical condition, has also closed "non-essential" services like amusement parks, beauty parlors, karaoke and massage parlors and bars.

While Da Nang has stopped welcoming tourists for 14 days starting 1 p.m. Sunday, tour agencies and travel companies can continue serving their customers under signed contracts while applying Covid-19 preventive measures.

The Da Nang People's Committee said its orders are effective until further notice.

Residents have been asked to maintain a minimum distance of one meter between people at work places, schools and hospitals.

Festive activities, religious ceremonies, sports tournaments and crowded events in public places, stadiums and big venues are banned.

Other protective measures it has undertaken include reducing the numbers of students in classrooms and encouraging people to wear face masks outdoors.

The moves come after Da Nang recorded two infections over the past few days, the first of which ended Vietnam's 99-day streak with no community transmission of the novel coronavirus.

"Patient 416", a 57-year-old man resident of the city, had tested positive for the virus five times as of Saturday morning. He remains in critical condition and faces a risk of death, doctors have said. "Patient 418", 61, also a Da Nang resident, is in severe condition, requiring ventilator support.

Authorities have yet to confirm the source of transmission for the two cases.

The Da Nang General Hospital, where the two are being treated, has been placed under a lockdown with more than 6,000 people, including 2,200 medical staff, 1,900 patients and 2,000 family members and caregivers

Both "Patient 416" and "Patient 418" had called on their family members at the hospital before they were diagnosed with Covid-19.

The National Steering Committee for Covid-19 Prevention and Fighting proposed to the Prime Minister Sunday that he deploys a 15-day social distancing campaign in the city under Directive 16, starting from 12 a.m, Monday. Directive 16 on social distancing, released in March, bans the gathering of more than two people in public places.

The committee also said that means of public transport to and from Da Nang must be restricted, and only one or two flights from domestic airports to the city allowed.

The Civil Aviation Administration of Vietnam (CAAV) has asked airlines to maximize the number of flights for tourists to leave Da Nang.

Truong Huu Khanh, head of the infection and neurology department at the Children's Hospital No.1 in Ho Chi Minh City, said a second wave of Covid-19 infections could break out in the country if people are neglectful and do not take preventive measures.

Khanh predicted the outbreak could potentially hit its peak in September since students will begin a new school year and people return to work after the summer break.

Vietnam had recorded 418 novel coronavirus cases as of Sunday morning with 365 recoveries. Of the 53 active cases, six have tested negative once or twice.