Whooping cough threat to unvaccinated

By Jane Collingwood

Tough measures to prevent infection may be the only effective way to protect unimmunised infants from catching whooping cough, experts warned today, revealing details of two tragic deaths.

Vaccination of infants has dramatically cut rates of whooping cough, or pertussis, but rates are rising among older children and adults, putting unimmunised infants at risk.

Infected adults are the main source of infection for unimmunised infants, state Dr Ulf Theilen and colleagues from the Royal Hospital for Sick Children, Edinburgh, UK, on the website of the British Medical Journal.

They report on two fatal cases of whooping cough in unvaccinated infants. In both cases death from whooping cough occurred after family members, some vaccinated, reported coughing for more than two weeks.

The authors say the antibodies transferred during pregnancy are insufficient to prevent infection. Infants below two months are at particular risk.

"Most infants catch the disease from affected household members – in more than half of the cases the parents," the authors write. This is highlighted during outbreaks in neonatal units, thought to be perpetuated by infected adult carers.

The experts suggest that immunity only appears to last for about four to 12 years after vaccination. Several countries have introduced booster doses for adolescents, and some for adults, but the authors warn that a high coverage rate of adults (more than 85 per cent) would be necessary.

They suggest that GPs test for whooping cough in cases of persistent cough, especially at night and with vomiting, in households with young infants.

"Introducing an adolescent pertussis booster, or more targeted vaccination of household contacts of this most vulnerable group, should be carefully considered," they conclude.

Theilen, U., Johnston, E. D. and Robinson, P. A. the British Medical Journal, 2008;337:a343.