Initial case was retrieved from the scientific literature on 30 January 2012. Verbatim from the report: "BACKGROUND: The emergence of pandemic H1N1 influenza virus in early 2009 prompted the rapid licensure and use of H1N1 and live, attenuated (LAMV) vaccines separate from seasonal trivalent inactivated (TIV) and live, attenuated (LAIV) influenza vaccines. A robust influenza immunization program requires ongoing monitoring of potential adverse events associated with vaccination. PURPOSE: To prospectively conduct safety monitoring of H1N1 and seasonal influenza vaccines during the 2009-2010 season. METHODS: The Vaccine Safety Datalink (VSD) Project monitors ~9.2 million members in eight medical care organizations. Electronic data on vaccines and pre-specified adverse events were updated and analyzed weekly for signal detection from November 2009 to April 2010 using either a self-controlled design or a current versus historical comparison. Statistical signals were further evaluated using alternative approaches to identify temporal clusters and to control for time-varying confounders. RESULTS: As of May 1, 2010, a total of 1,345,663 MIV, 267,715 LAMV, 2,741,150 TIV, and 157,838 LAIV doses were administered in VSD. No significant associations were noted during sequential analyses for Guillain-Barre syndrome, most other neurologic outcomes, and allergic and cardiac events. For MIV, a statistical signal was observed for Bell's palsy for adults aged greater than or equal to 25 years on March 31, 2010, using the self-controlled approach. Subsequent analyses revealed no significant temporal cluster. Case-centered logistic regression adjusting for seasonality demonstrated an OR for Bell's palsy of 1.26 (95% CI-0.97, 1.63). CONCLUSIONS: No major safety problems following H1N1 or seasonal influenza vaccines were detected in the 2009-2010 season in weekly sequential analyses. Seasonality likely contributed to the Bell's palsy signal following MIV. Prospective safety monitoring followed by rigorous signal refinement is critical to inform decision-making by regulatory and public health agencies." According to the authors, "prospective weekly surveillance was conducted from November 2009 to April 2010 on pre-specified potential adverse events selected for being clinically well defined, serious, and potentially associated with influenza vaccines. Potential adverse events identified by ICD-9 code data and occurring in pre-specified risk intervals after each patient's first dose of H1N1 or seasonal influenza vaccine monitored in the 2009-2010 season included GBS, demyelinating disease of the central nervous system, disorders of the peripheral nervous system and neuropathy, seizures, encephalomyelitis, Bell's palsy, other cranial nerve disorders, ataxia, anaphylaxis, and allergic reaction other than anaphylaxis (including angioneurotic edema and urticaria). Myocarditis/pericarditis was also monitored after live, attenuated vaccines. Risk-interval durations were based on published studies as well as biologic plausibility. To optimize specificity, adverse events were included only if they were the first event in either a 6-month or 1-year period." All cases were adjudicated by at least two neurologists with expertise in demyelinating disease using the GBS and Fisher syndrome definitions. Among 11 potential neurologic, allergic, and cardiac adverse events being monitored in different age groups in weekly sequential analyses during the 2009-2010 season, there was only one with a statistical signal. For MIV, there was a signal for Bell's palsy for adults aged greater than or equal to 25 years on March 31, 2010, with 141 observed cases compared to 88 expected, for a relative risk of 1.60. By May 1, 2010, there were 157 cases of Bell's palsy identified by ICD-9 code 351.0 in the risk interval and 94 in the comparison interval among MIV vaccinees, for a relative risk of 1.67. No statistical signals were observed for LAMV, TIV, or LAIV vaccination. The temporal scan statistic did not find any significant clusters. A case-centered analysis was then conducted and adjusted for case date, age group, gender, and site. There was no significant association between Bell's palsy and being vaccinated in versus out of the risk interval with MIV. No association between Bell's palsy and TIV was observed using the case-centered approach. Documents held by sender: none.