2009 H1N1 Webinar FAQ
Q: Was there really an increased risk of Guillain-Barré syndrome (GBS) following the 1976 H1N1 vaccination season?
A: In 1976 during the H1N1 vaccination, the attributable risk (in other words, the number of cases of GBS attributed to the vaccine) of GBS following the vaccination was a little less than 1 excess case of GBS per 100,000 vaccinees, among the 46 million persons vaccinated for H1N1. Subsequent assessments of the risk of GBS following seasonal influenza vaccines since 1976 have failed to consistently demonstrate any similar increase in risk. The current H1N1 vaccine is manufactured in the same way as current seasonal influenza vaccines. Although there have been advances in vaccine development since 1976, we still don't know why there appeared to be an increased risk of GBS in 1976, and so that is one reason we are proceeding with an abundance of caution this year.
Q: In those participants who have been in the pre-clinical trials for the H1N1 vaccine, have you seen any cases of GBS related to the vaccine?
A: To our knowledge, there have been no cases of GBS in the pre-clinical phase of testing the H1N1 vaccine.
Q: Is there serological testing available to confirm whether or not someone had H1N1 and thus wouldn't need the vaccine?
A: A diagnosis of H1N1 influenza infection is made by the performance of various rapid tests of respiratory or nasopharyngeal secretions, looking for H1N1 influenza antigen or nucleic acid, not serology. Most health departments are recommending definitive H1N1 testing for high-risk patients with influenza-like illness. However, if someone had suffered an influenza-like illness during last spring, it's fairly likely that it was the H1N1 virus and that they were infected with the same serologic type of H1N1 influenza virus. This season, both H1N1 and seasonal influenza virus strains are co-circulating, and in the absence of testing, it would be prudent to get the H1N1 and the seasonal influenza vaccines and not presume that there had been antecedent immunological protection from a previous infection.
Q: I was contacted by my state's EIP to report cases of GBS in the setting of the vaccine. Can we expect that all of the neurologists in a group practice will be contacted or is it just one person per practice group?
A: The point of contact person can be one person; for instance, if you work in a large group practice or academic setting, one contact for the entire group or department would be good. For instance, if you are in a group with other colleagues, please identify the most efficient way that the various members of the group can coordinate and relay information about possible cases of GBS to the EIP surveillance officer who is in contact with your group.
Q: Is the H1N1 vaccine a live, attenuated virus or a killed virus?or parts of a dead virus?
A: The flu mist is a nasal spray that is a live, attenuated virus vaccine. The injectable vaccine is an inactivated particle vaccine. People who have underlying immune compromise or are otherwise immunosuppressed are recommended to get the injection and not the flu mist.
Q: Do patients who either had the flu in '76 or had the vaccine in '76 need to be reimmunized?
A: Yes.
Q: What was the length of time between the administration of the vaccine and the onset of GBS in the 1976 cases?
A: In 1976, about three-quarters of patients developed GBS within four weeks of receiving the vaccine, with the majority occurring during the second and third week post-vaccination. The elevated risk of GBS lasted out to six weeks.
