The Civil Aviation Authority of Vietnam (CAAV) has ordered airlines to maximize the number of flights from Da Nang as "80,000 people are stuck in the city", where three people have been diagnosed with the disease in the past few days, the country's first cases after 99 days without community transmission.
On Sunday it granted permission to Vietjet Air, Pacific Airlines and Bamboo Airways to operate more flights.
It is awaiting approval from the Transport Ministry to allow flights to the city for at least the next four days.
Dinh Viet Thang, head of the CAAV, said passengers stuck in Da Nang could run out of money, lack accommodation and face other difficulties since authorities have imposed social distancing measures.
On Sunday more than 40 check-in counters at Da Nang International Airport were chock-full of passengers, all wearing face masks.
Tran Van Trung of Ho Chi Minh City had gone there for a five-day vacation with a friend on Friday, but, following the outbreak, changed plans and flew back on Sunday night.
"I was not worried while in Da Nang because I believe the government and health authorities will stem the Covid-19 outbreak," he said. "But I feared being quarantined (at home) for 14 days when I return home that would affect my work."
Thi Quoc Duy, deputy general director of BenThanh Tourist’s Da Nang office, said 300 customers from across the country have contacted his office to cancel tours to Da Nang.
Nguyen Nguyet Van Khanh, deputy director of marketing at Vietravel, another leading travel company, said initial estimates show that in July alone her firm would have to cancel 110 group tours for 4,500 individuals.
One of the most popular tourist attractions in Vietnam, Da Nang has been receiving a large number of visitors after the government relaxed social distancing measures in April and sought to bolster domestic travel.
But with the news of community transmissions, people are leaving the city en masse.
The airport is temporarily closed to international flights that occasionally bring foreign experts and Vietnamese citizens from abroad.
The government Monday morning ordered social distancing in the city under Directive 19, effective for at least 14 days from Tuesday. Directive 19 on social distancing requires people to maintain a distance of at least one meter from each other and prohibits gatherings of more than 20 people in public, except in offices, schools and hospitals.
Da Nang has stopped receiving tourists for 14 days starting on Sunday afternoon. Tour agencies and travel companies can continue serving their customers under signed contracts while applying Covid-19 preventive measures.
Besides the three people in Da Nang, one more person has been diagnosed with Covid-19 in nearby Quang Ngai Province. Health authorities have yet to confirm what are the infection sources for the cases.
Of Vietnam’s 420 Covid-19 cases to date, 55 are active infections as 365 have recovered after treatment.