BETHESDA, MD. — Monitoring of influenza A(H1N1) vaccine safety in studies conducted across multiple U.S. government agencies have shown no safety signals of concern so far, nationally or internationally.
The multiple data collection efforts—some preexisting and others a result of the pandemic H1N1 outbreak—represent “strengthened collaboration and communication among government agencies and internationally, with enhanced capacity for timely signal detection, strengthening, and confirmation,” Dr. Hector Izurieta told the Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee.
In addition to the FDA, other participating agencies include the Centers for Disease Control and Prevention, the Department of Defense, the Department of Veterans Affairs, the Centers for Medicare and Medicaid Services, and the Indian Health Service, Dr. Izurieta, chief of the FDA's analytic epidemiology branch, said in an interview.
For example, the CDC is currently evaluating 205 reports of serious adverse events following H1N1 vaccine in the Vaccine Adverse Events Reporting System (VAERS). Of those, 70 are among pregnant females. All but 13 were nonserious and none involved maternal death.
Eight deaths following receipt of H1N1 vaccine have been reported to VAERS, including two following live attenuated (intranasal) vaccine and six after inactivated (injected) vaccine. The three that have been evaluated so far had severe underlying conditions. There have been 29 reported cases of anaphylaxis, which is consistent with published estimates following other vaccinations, he said.
Two cases of “possible or probable” Guillain-Barré syndrome have been reported within 1 day of H1N1 vaccine receipt. The short interval “decreases but does not eliminate” the possibility that H1N1 vaccine caused the event. However, to date the rate of reported GBS cases is less than the background rate in the population, Dr. Izurieta said.
Dr. Claudia Vellozzi of the CDC's Immunization Safety Office described the Vaccine Safety Datalink (VSD), an active surveillance program of both the CDC and managed care plans that cover more than 9.5 million people, or 3.1% of the U.S. population, and is used to follow up on safety “signals” obtained from VAERS.
VSD analyses of pregnant women and of 10 GBS cases identified so far have shown no significant associations with either H1N1 or seasonal vaccine, although it's still early, she said.
Dr. Richard Platt of Harvard Pilgrim Health Care and Harvard Medical School, Boston, described a new safety analysis that his institution will conduct in collaboration with health plans covering approximately 25 million people and nine state immunization registries comprising a total population of 14 million; it is called Post-Licensure Rapid Immunization Safety Monitoring.