Pertussis vax only good for a year: study

The booster vaccine Tdap (dTpa) wanes rapidly and provides only limited, short-term protection against pertussis when administered to teenagers.

This is the surprise finding from a US study of more than 270,000 children who were followed from infancy to adolescence.

The results, based on 1207 pertussis cases, suggest dTpa may be more effective if administered