Delicately and cautiously, health authorities in the United States and other countries are beginning to open up a difficult topic: Whether the extraordinary ongoing epidemic of whooping cough, the worst in more than 50 years, may be due in part to unexpected poor performance by the vaccine meant to prevent the disease.
That possibility, captured in several recent pieces of research — one published last night — is being raised so carefully because it might lead vaccine opponents to claim incorrectly that pertussis vaccination does not work. That fear contains a deep irony: The current vaccine, in use for about 20 years, replaced an older and more effective one that went out of use because vaccine critics charged it had too high a rate of side effects.