All four children who died after being administered the measles vaccine in Tamil Nadu on April 23 suffered severe brain hemorrhage resulting from an anaphylactic shock, an inquiry has found.
This will be pointed out by the five-member expert team sent by the health ministry to investigate the deaths, when they submit their initial report to health minister A Ramadoss on Monday. Experts in the team said an anaphylactic shock – a severe, potentially lethal systemic allergic reaction – following a measles vaccination is highly rare and occurs in 1 out of every 10 lakh cases.Experts in the team said that anaphylactic shock killing all four children – within half-an-hour of being administered the vaccine around the same area – pointed to two likely reasons of why the deaths occurred – a human error resulting in mixing the freeze-dried vaccine with a different chemical in place of saline water or a contaminated vaccine containing a foreign protein like a bacteria because of being kept in the open for more than three hours after being reconstituted.
A central team member who returned from Chennai on Friday after investigations, however, confirmed that the public health centre’s cold chain system, which was used to store the vaccines, was not at fault.
Putting to rest allegations that the nurses may have used the same syringe to vaccinate the three children after dipping it in chemicals like adrenalin or muscle relaxants, the team found that individual syringes were used.
The expert told TOI, “There was no conflict between what the nurses, anganwadi workers and family members of children who died told us. The cold chain system was fine. Police reports also showed that individual syringes were used. However, the government hospital which carried out the post-mortem found all died of haemorrhage, which is strange.”
The Central Drug Laboratory, meanwhile, started testing 20 samples of the vaccine from the same batch that killed the children – 10 each collected from the fatal site in Tiruvallur and those lying with Human Biologicals Institute in Hyderabad.
Worried about HBI’s good manufacturing standards, the health ministry is now dispatching a three-member team to HBI on Tuesday to check the PSU’s measles vaccine production unit.
“HBI is a pre-qualified WHO unit. However, we need to be sure that it is following good manufacturing standards set by WHO and the government of India. The team will inspect the vaccine production area, check raw materials being used and inspect its quality control measures,” a health ministry official said.
He added, “This case is really intriguing. A single child can be sensitive to the vaccine and suffer from an anaphylactic shock. But how can it occur on three children, one after another, after being administered the vaccine from a single vial. On the other hand, records show that 230 doses of the same vaccine batch were used in the same PHC that day but no other deaths were recorded.”
The fatal vaccine batch was manufactured in February 2008 with expiry date of January 2010. Out of about 2.5 lakh doses of vaccine manufactured, 1.45 lakh doses were supplied to Tamil Nadu. The rest were sent to nine other states.
“Around 20,000 doses of the vaccine from the same batch were used between April 4-23 without a single death. Over 230 children were vaccinated across seven villages on April 23 but no serious adverse reaction was detected,” an official said.