A 3-month-old boy died in the Central Highlands on Thursday soon after he was given Quinvaxem, the controversial 5-in-1 vaccine that Vietnam suspended for five months in 2013 following several infant deaths.

News website Zing quoted family members as saying that they had the boy vaccinated at a public clinic in Dak Nong Province in the morning.

He became very weak and turned pale a few hours later. He died soon after they brought him to a local hospital.

Forensic tests have not come up with a conclusion.

A local health official said around 20 other babies received Quinvaxem shots from the same batch that morning and they are all fine.

Quinvaxem is given to infants in Vietnam for free as part of a national immunization program to protect children against diphtheria, tetanus, whooping cough, hepatitis B and Haemophilus influenza type B infections.

It is a WHO prequalified drug and is much cheaper than alternatives.

Berna Biotech Korea Corp. has distributed it in Vietnam since 2010.

The health ministry suspended the vaccine on May 4, 2013 after nine infants died between November 2012 and March 2013.

After the ministry’s investigation found that the deaths were not related to the use of the vaccine, it was reintroduced in October the same year.

Six infant deaths since Quinvaxem was brought back have not been linked to the vaccine either.