A 4-year-old suffered a slashed forehead, a 6-year-old a grazed finger, while an 11-year-old was heavily wounded on the cheeks, temples and lower jaw, said doctors at the Children's Hospital No.1.

All three have since been screened for HIV, prescribed antiretroviral drugs and taken home for further surveillance.

The children were playing near their homes when attacked by a male stranger, their families confirmed.

Antiretroviral drugs must be taken within 72 hours following exposure to HIV, and continued for four weeks, the Ministry of Health recommends.

Vietnam has some 250,000 registered addicts and around 10 percent of them are in HCMC.