An immunisation programme in India that included the DTP jab and three oral doses of the poliomyelitis vaccine has left thousands of children paralysed.
Experts believe the DTP jab caused provocation poliomyelitis, a phenomenon that can occur when an injection triggers a "silent" poliovirus infection already present.
The problem was compounded by the inadequate protection offered by just three doses of the oral vaccine, according to Dr Thekkekara Jacob John, president elect of the Indian Academy of Pediatrics.
The incidence of recorded poliomyelitis in India dropped from 38,000 cases in 1981 to 8000 cases in 1995, but it has been reckoned that only one third of all cases are ever reported.
The immunisation programme was based on a World Health Organisation recommendation, but Dr John commented: "The large scale introduction of DTP vaccine in a country hyperendemic for polio viruses without appropriate steps to protect children from polioviruses was unscientific and cruel."
Although poliomyelitis is on the decline, a variant known as Japanese encephalitis virus (JEV) has been detected. Children with JEV suffer acute flaccid paralysis, similar to poliomyelitis (Lancet, 1998; 351: 1094-97).