A three-month-old boy from the northern province of Quang Ninh died at home on Friday morning, one day after given a shot of the controversial 5-in-1 vaccine Quinvaxem.
The boy received the shot and a dose of the oral polio vaccine Thursday morning at a local medical center.
A family member said he showed no abnormal signs before death. His mother breastfed him one hour before that and put him to sleep. He did not wake up.
Quang Ninh's health department has ordered local officials to seal the vaccine batch and review the administration process to investigate the cause of death.
A source from the department said 89 other babies receiving the vaccine on the same day are all fine.
Quinvaxem is a WHO prequalified drug and has been distributed in Vietnam by Berna Biotech Korea Corp since 2010 under a national immunization program sponsored by the global vaccine alliance GAVI. It protects children aged two months upward against diphtheria, tetanus, whooping cough, hepatitis B, and Haemophilus influenza type B.
Babies are given the vaccine for free, but it has lost much of the public trust following the post-vaccination deaths of at least 21 since late 2012.
Supplies of alternatives such as the French-made Pentaxim, which costs around US$30 a shot, are limited and almost impossible to secure.
Quinvaxem uses whole-cell preparations in its whooping cough component while costly alternatives use purified antigens, which are considered safer.
Vietnam provides around 5.5 million Quinvaxem shots every year and up to 200,000 of the alternatives, according to official data.