Hanoi's Preventive Medicine Center said on April 21 that the cause of death of a four-month-old baby in Hanoi soon after getting a vaccine is unclear.

Initial investigations reveal that the child from the capital’s Thanh Xuan District was taken to the Thanh Xuan Bac Ward medical center on April 18 for a routine vaccine -- known as Infanrix hexa --against diphtheria, tetanus, whooping cough, hepatitis B, and polio, and diseases caused by Haemophilus influenzae type B (HiB).

After the shot he was monitored at the health center for 30 minutes and he showed no symptoms of shock.

But at 7PM he was physically exhausted and was rushed to the Construction Hospital immediately, but died on the way.

According to the victim’s family, he was healthy before getting the inoculation.

The investigation also found medical workers administering and storing the vaccine in a proper way.

It was also given to eight other babies on the same day but they are all healthy.