Whooping cough protection wanes, even after five doses

Children's protection against whooping cough wanes within five years of vaccination, even when they are given five doses, a US study has shown.

Whooping cough vaccine protection was studied in US children (photo:SPL)
Whooping cough vaccine protection was studied in US children (photo:SPL)

Dr Nicola Klein and colleagues compared Californian children’s risk of developing pertussis with the time since their last dose of diphtheria, tetanus and acellular pertussis (DTaP) vaccine.

In the US, children receive five doses of DTaP vaccine before the age of seven. In the UK, children are vaccinated against pertussis at two, three and four months of age, and again before starting school at about three years and four months of age.

The researchers examined the time since vaccination for 277 children aged 4 to 12 years who had pertussis confirmed by a polymerase-chain reaction (PCR) assay. They compared these results with 3,318 children whose pertussis was negative on a PCR assay and 6,086 matched controls.

The researchers found that, after the fifth dose of DTaP, the odds of acquiring pertussis increased by 42% each year.

In the UK, whooping cough cases are continuing to rise with 1,047 cases being confirmed in July 2012, almost as many as in the whole of 2011. There were 3,523 confirmed cases of pertussis in the first seven months of 2012, more than three times more than in 2011, when 1,118 cases were reported.

DH advisors at the Joint Committee on Vaccination and Immunisation (JCVI) are reviewing a number of possible changes to the vaccination schedule. These include the introduction of a booster dose in teenagers and offering vaccination to pregnant women.

Surrey GP Dr Saul Galloway had two pertussis cases in his practice last month, both confirmed by serology and both in fully vaccinated individuals.

‘Pertussis in vaccinated individuals used to be unheard of, and serious questions should be asked about what’s going on here,’ he told GP.

'Certainly my practice is now alerted to enquiring about paroxysmal cough, coughing until vomits, and inspiratory "whoop" regardless of vaccination status.’

Dr Galloway said the research by Dr Klein ‘suggests that simply more of the same won't cut it’.

‘Given that the current vaccine is failing, though the reason for that is not entirely clear, the decision to simply add in more boosters with the same DTaP vaccine is surely only a short-term holding measure, if it even does that,' he said.

In July, a group of US public health researchers warned that whooping cough would continue to kill young infants unless more effective and longer-lasting vaccines are developed.

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