The Ministry of Health issued an urgent warning about a potential diptheria outbreak in central Vietnam, on Wednesday.
Earlier this month, two teenagers from Tay Giang District died of the bacterial infection in the central province of Quang Nam, prompting the warning, according to VietnamPlus.
In the past, the disease could be found in many parts of the country, but an immunization campaign has eradicated the illness in all but the most remote communities.
Tay Giang is a mountainous district mainly populated by ethnic minority people.
The ministry asked local people to strictly implement preventive measures to try to keep the disease from spreading, including best hygiene practices and close monitoring of patients at hospitals.
The outbreak occurred at the Tay Giang District High School, which has nearly 800 students and around 70 teachers and staff members. Of the five cases under treatment, two students have died.
Health officials are monitoring 24 other suspected cases, including people who came into contact with the patients.
Symptoms of the disease include fever and chills, difficulty breathing and swollen glands in the neck.
Medical experts from Nha Trang Pasteur Institute say disease is spread through respirtory droplets created in coughing and sneezing. The bacterium that causes the disease can be spread through third objects, like toys or blankets.
The highly contagious disease killed three patients in another mountainous area of Quang Nam Province, two years ago.