a b s t r a c tIn preparation for pandemic vaccine safety monitoring, we assessed adverse events reported to the Vaccine Adverse Event Reporting System following receipt of trivalent inactivated influenza vaccines among adults from 1990 through 2005. We calculated reporting rates for nonserious, serious, and neurological adverse events. We reviewed reports of recurrent events and deaths, as well as reports identified through advanced signal detection. The most frequently reported events were local reactions and systemic symptoms. Guillain-Barré syndrome was the most frequently reported serious event (0.70 reports per million vaccinations). Adverse event reporting rates have been reasonably constant over time. No new safety concerns emerged after our review of 15 years of post-licensure surveillance data. These findings provide useful information if pandemic vaccine is rapidly distributed and pre-licensure data are limited.Published by Elsevier Ltd.
BackgroundInfluenza vaccines are the primary method for the control of influenza and its complications and the most widely used type of vaccine for adults in the United States (US). The US and much of the world is preparing for the use of pandemic influenza vaccines [1]. However, even with extensive planning, limited safety data will be available for these vaccines prior to use. Safety profile highlights of the seasonal trivalent inactivated influenza vaccines (TIV) can provide a background for interpretation of adverse events that can be anticipated if pandemic influenza vaccines must be employed in the future. In addition, special importance for TIV safety monitoring stems from the 1976-1977 influenza season, when a mass vaccination effort in the US against swine influenza was halted after the vaccines appeared to be associated with an elevated risk of Guillain-Barré syndrome (GBS) [2].Placebo-controlled trials among older and healthy young adults have demonstrated that TIV administration is not associated with an increased risk of systemic symptoms (e.g., fever, malaise, myalgia); the most frequent adverse effect following vaccination is pain at the injection site [3] including anaphylaxis can occur [3], but the latter is rare [4]. A pre-licensure study of the recently licensed H5N1 vaccine identified headache, malaise, and myalgia as the most frequent systemic symptoms but also identified these at similar rates among placebo recipients [5]. Clinical trials are generally not large enough to detect rare adverse events. Post-licensure safety data provide examples of adverse event experiences among a larger and more diverse population, and reporting of adverse events following receipt of seasonal TIV to the US Vaccine Adverse Event Reporting System (VAERS) is an important source of this information. We examined 15 years of VAERS data among adults aged ≥18 years to describe patterns of adverse events after seasonal vaccines and to identify possible safety concerns that might merit intensified monitoring or evaluation. Although pandemic influenza vaccines will differ fr...