Effectiveness of acellular pertussis vax only 50–60%

The case-controlled study compared 668 PCR-positive cases with 10,000 PCR negative controls, and 21,000 matched controls from a Californian database.

The estimate of vaccine effectiveness was 53% when the PCR-positive cases were compared with the PCR negative controls, and 64% effective when compared with the matched controls.

The effectiveness of DTP vaccine was broadly the same in those given whole cell and acellular vaccines in childhood, but only around 25% effective in those not