The boy is a neighbor of the first victim, a nine-year-old girl who died on June 20.
Doctor Nguyen Van Vinh Chau, Director of the HCMC Hospital of Tropical Diseases, said the boy, Giang A Phu, suffered complications from diphtheria that triggered a heart failure.
Phu, a resident of Dak Glong District, Dak Nong Province, was diagnosed with diphtheria after developing a fever and having swollen glands in the neck.
He was first treated at the Central Highlands General Hospital. On June 26, he was transferred to HCMC Hospital of Tropical Diseases in critical condition. His heartbeat had become irregular and he had trouble breathing. After seven days of treatment, the boy succumbed to the disease.
Phu’s neighbor, the nine-year-old girl also died of diphtheria complications at the same hospital. Both were members of the H’Mong ethnic community.
Dak Nong has recorded 15 cases of diphtheria in the latest outbreak, the country's highest number. Kom Tum Province in the Central Highlands also has three patients being treated at local hospitals. Hundreds in the infected areas have been quarantined and are being vaccinated against the disease.
One patient in HCMC has recovered and been discharged.
Last year, two diphtheria-related deaths were recorded in Kon Tum. In 2017, four people died of the infection in the central province of Quang Nam.
Vietnam has managed to contain the disease for years through the national vaccination and immunization program.