Lisa Schnirring
CIDRAP
06/02/2010
The risk for the paralytic condition called Guillain-Barre syndrome (GBS) in people who received pandemic H1N1 influenza vaccine was about the same as the risk among those who receive seasonal flu shots, according to preliminary findings released today by the US Centers for Disease Control and Prevention (CDC).
GBS is a rare side effect of illness or vaccination and was linked to the 1976 swine flu vaccine. Today’s preliminary analysis from the CDC’s Emerging Infections Program (EIP) suggests there were 0.8 excess cases of GBS per 1 million vaccinations, whereas surveillance for the 1976 pandemic vaccine showed about 10 excess cases per 1 million vaccinations. The CDC published the findings in an early-release edition of Morbidity and Mortality Weekly Report (MMWR).
The CDC’s EIP, a collaboration between state health departments and academic centers, conducts disease surveillance in 10 states. Today’s analysis covers patients who were hospitalized with GBS after September 30, 2009, just as the vaccine launched. Researchers interviewed patients who met the GBS classification definition by phone to gather more information about their medical and vaccination history.
The group calculated GBS incidence for vaccinated and unvaccinated populations by using data from the CDC’s Behavioral Risk Factor Surveillance System and its national 2009 H1N1 flu telephone survey.
The EIP identified 326 GBS cases that met the case criteria, of which 27 patients had received the pandemic vaccine within 42 days before illness onset and 274 had not received the vaccine. Status was unknown or pending for 25 of the cases. Sixteen (59%) of the 27 who had received the pandemic vaccine also reported other illness symptoms in the 42 days before GBS onset. Meanwhile, 78% of unvaccinated patients reported other illness symptoms before GBS onset.
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