In the evaluation of pH1N1 influenza vaccinations administered to pregnant women, researchers found no meaningful evidence of increased risk for specific congenital malformations following pH1N1 influenza vaccinations in the 2009–2010 and 2010–2011 seasons, according to study results presented in 2 companion papers published online in the journal, Vaccine.
The results come from a national study by the Vaccines and Medications in Pregnancy Surveillance System (VAMPSS), a collaboration between the American Academy of Allergy, Asthma and Immunology (AAAAI) and investigative teams at University of California, San Diego and Boston University.
Among women exposed to the pH1N1 vaccine, there was a decreased risk for preterm delivery (PTD) during the 2010–2011 season, with an increased risk in 2009–2010, particularly following exposure in the first trimester, though the decrease in gestational length was less than 2 days.
“The overall results of the study were quite reassuring about the safety of the flu vaccine formulations that contained the pandemic H1N1 strain given in these three seasons,” said Christina Chambers, PhD, lead investigator of UC San Diego’s team. “We believe our study’s results can help women and their doctors become better informed about the benefits and risks of vaccination during pregnancy.”