Passengers on two flights from Da Nang to Ho Chi Minh City last week are asked to immediately contact local health authorities as one passenger on each flight is now COVID-19 positive.
The Ho Chi Minh City Center for Disease Control (HCDC) announced on Friday evening it was looking for passengers on the flights QH159 and BL671 from Da Nang, which arrived in Ho Chi Minh City on July 24 and July 25, respectively.
A passenger on each of the flights has tested positive for the novel coronavirus, it said.
The two passengers were among the three latest local infections reported in the southern metropolis on Friday evening.
All passengers on these two flights are asked to immediately contact the health authority where they live to receive health examination and instructions on disease prevention.
Passengers residing in Ho Chi Minh City can reach the hotline numbers of district-level health centers or the HCDC available below for further instructions.
All flights to and from Da Nang have been suspended from Tuesday as the coastal tourist city entered 15 days of enhanced social distancing to curb the spread of COVID-19.
Da Nang reported a community-based case of COVID-19 on Saturday last week, breaking Vietnam's streak of 99 days without a local infection.
Since then, 116 locally transmitted cases have been confirmed nationwide, all linked to the outbreak epicenter in the central city where at least 87 cases have been reported.
Vietnam's COVID-19 tally sits at 558, with 373 recoveries and three deaths as of Saturday morning.
A dozen patients are in critical condition, mostly due to severe underlying conditions.