A booster vaccination for parents of new babies and other household members can significantly protect infants against the fatal form of whooping cough, say doctors.

Citing examples of two fatal cases of invasive pertussis in unvaccinated young infants, paediatricians Royal Hospital for Sick Children in Edinburgh explained the how infectious adults within a family can be the source of infection for unimmunised infants, reports the British Medical Journal.

In the first case, a one-month old boy was suffering from cough, runny nose and difficulty feeding for the past five days. Both parents and an elder sibling also reported persistent coughing with vomiting in the previous two weeks.

While the elder sibling was fully vaccinated, there was no record of the parents’ childhood vaccination status, but the mother received a pertussis booster in 1986.

Despite maximum therapy, the 1-month-old infant died within 24 hours.

In another case of a six-week old girl, who also suffered from history of cough and breathlessness, the doctors found that her mother had a persistent cough for more than two weeks.

While the mother had received all her childhood immunisations including pertussis, there was no record of the father’s pertussis immunisation.

Despite maximum therapy, the infant died within 30 hours.

The doctors suggested that most infants catch the disease from affected household members, with parents accounting for more than half of the cases.

The author suggests that the introduction of an adult booster or more targeted vaccination of household contacts of young infants should be considered.