THIMPHU: Random samples of the pentavalent vaccine, which has been suspended following the deaths of eight infants, are being collected from across the country to be sent for quality tests to independent laboratories that are yet to be identified. It is part of the investigation process that began on October 29 with the arrival of an expert team from the World Health Organization (WHO). The expert team, in their preliminary findings, categorised eight of the deaths as coincidental and linked only one to the vaccine. The health ministry suspended the use of pentavalent vaccine on October 23, after four deaths were reported. “Drug regulatory officials will collect these vaccines and send it for testing,” said the public health director, Dr Ugen Dophu. “Just now even the experts cannot say that the vaccine is not at fault. But certain conclusions can be drawn,” he said. “If the problem is with the vaccine, then all districts should have reported similar cases but there has been none from the east. The number of cases would have also been more and if it was reported from only one place, then we can say that there was a program error,” said Dr Ugen Dophu.

He said that deaths related to the vaccine were not at all expected. “We were expecting other side effects like hypotonic-hypo responsive episodes (HHE), fever and vomiting, not deaths,” he said. Such side effects are also expected with the conventional tetravalent vaccine, which is now being given in place of the pentavalent vaccine.

Although Bhutan’s immunisation programme began in 1979, the ministry started documenting Adverse Effects Following Immunisation (AEFI) only from 2006. Last year, there were seven AEFI cases of tetravalent vaccine like mild fever, crying, swelling and redness at the site of injection. Of these, one was due to program error, meaning an error in handling or injecting the vaccine. This year, the health ministry recorded three cases.

The recent nine suspected cases have not been filed under this category.

Bhutan had been processing for the pentavalent vaccine with global alliance for vaccine initiative (GAVI) since 2006 said health officials.

“A disease burden study of haemophilus influenza type B was done in the country and the health ministry decided to introduce the vaccine,” said Dr Ugen Dophu. Haemophilus influenza type B germ is the most common cause of pneumonia and meningitis in babies in Bhutan.

The pentavalent vaccine contains antigens against diphtheria, pertusis, tetanus, hepatitis B and haemophilus influenza B. “The virus of all these diseases are killed but not the antigen, a substance on the surface of a virus, that stimulates the body to produce antibodies,” said Dr Ugen Dophu.