, said Yang Pan, PhD, of the Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, and associates.
School-based trivalent inactivated influenza vaccination programs generally occurred Oct. 15-Nov. 30 each year since 2007, with greater than 50% vaccination coverage. In an 11-year retrospective study of school outbreaks of influenza in elementary, middle, and high schools in the Beijing area during Sept. 1, 2006-March 31, 2017, there were 286 febrile outbreaks in schools, involving 6,863 children.
A total of 81% were caused by influenza A/B virus (231 outbreaks), including influenza A(H1N1)pdm09 (58 outbreaks), A(H3N2) (123 outbreaks), B(Victoria) (46 outbreaks), and B(Yamagata) (4 outbreaks). A total of 17 outbreaks were negative for flu testing, and 38 failed in testing because samples were unavailable.During the 11 years, a mismatch between circulating strains and vaccine strains was identified in two influenza seasons, such as “the A(H3N2) 3C.1 (vaccine strain)-A(H3N2) 3C.3a (circulating strains) mismatch in 2014-2015, the B(Yamagata) Clade 2 (vaccine strain)-B(Yamagata) Clade 3 (circulating strain) mismatch in the 2014-2015 influenza season, and B(Yamagata) (vaccine strain)-B(Victoria) (circulating strains) mismatch in 2015-2016,” they reported.
A combination of high flu vaccine coverage because of school-based vaccinations and a good vaccine match reduced influenza outbreaks in schools by 89% (odds ratio, 0.111), Dr. Pan and associates concluded.
“The school-based influenza vaccination program has been in operation for nearly 10 years in the Beijing area, is unique in China, and is one of the few school-based influenza programs in the world,” the researchers explained. “These data can inform and improve vaccination policy locally and nationally.”
Read more in Vaccine (2017 Nov 8. doi: 10.1016/j.vaccine.2017.10.096).