Influenza Vaccine (Split Virion), Inactivated, Quadrivalent in Pregnant Women

This is a randomized, double-blind, positive controlled phase Ⅲ clinical trial to assess the immunogenicity and safety of Sinovac QIV in pregnant women. A total of 150 healthy pregnant women aged 18\~39 years at 20 to 32 weeks of pregnancy will be enrolled. All participants will be randomized to test group and control group in a ratio of 2:1 and receive one dose of vaccine (0.5 mL) of Sinovac QIV or Vaxigrip QIV, respectively. Blood samples will be collected from participants prior to vaccination and 28 days after vaccination. Moreover, to evaluate trans-placental antibodies, blood samples at the end of the gestation period (delivery) and the cord blood sample will be collected, if applicable. For safety assessment, any immediate adverse events within 30 minutes, solicited local and systemic adverse events within 7 days and unsolicited adverse events within 28 days will be collected. Serious adverse events will be collected within 8 weeks after delivery. Pregnancy and birth outcomes will be collected as well.