Tran Dac Phu, an official with the General Department of Preventive Medicine under the Health Ministry, confirmed Wednesday that the girl, H'si Yan, was taken to a local hospital last Thursday with symptoms linked to diphtheria, including fatigue and difficulty in breathing.

She died the next day. Her parents and a neighboring child later tested positive for diphtheria and 31 others are suspected of being infected with the extremely contagious disease, prompting local health authorities to quarantine them for examination.

Around 7,000 residents aged between seven and 45, who are at a high risk of infection, have been listed to receive anti-diptheria vaccinations. As of Wednesday morning, 1,000 had been vaccinated.

Local authorities are also taking other urgent measures to stop the disease from spreading, including testing for the bacteria and spraying disinfectant.

Every person who is successfully vaccinated helps slow the spread of the infection, reducing risks to unvaccinated people, said Nguyen Trung Cap, deputy head of the emergency department at the Central Hospital for Tropical Diseases.

He explained further that the more the people vaccinated the higher the chance of "herd immunity," which refers to a community’s resistance to disease if sufficient numbers of people acquire immunity, especially through vaccination.

Those who are not immunized are much more highly likely to become infected in case of an outbreak in a community where the vaccination rate is low.

Diphtheria, a bacterial infection, can result in high fever, sore throat, swollen glands in the neck, and loss of appetite. In severe cases, it can cause life-threatening complications like difficulty in breathing, pneumonia, nerve damage, paralysis and damage to the heart muscle.

Last year, Vietnam reported two deaths linked to diphtheria in the Central Highlands province of Kon Tum. In 2017, four people died of diphtheria in the central province of Quang Nam.

The country has managed to contain the disease for years through the national vaccination and immunization program.