Influenza Vaccine Effectiveness of a Quadrivalent Vaccine in Pregnant Women and Young Infants, 2019-2020

Overview

Influenza is associated with an increased risk for serious illness, hospitalization and death in pregnant women and young infants. The investigators estimated the effectiveness of a quadrivalent inactivated influenza vaccine (QIV) in pregnant women and their infants in 2019-2020 influenza season. Women were activelly followed during the influenza season on a weekly basis through telephone call in order to collect data about the onset of fever and/or respiratory symptoms by them or their young infants. Polymerase chain reaction testing in pharyngeal samples was offered to pregnant women and infants with influenza-like illness (ILI). A total of 636 pregnant women and 474 infants were studied. A Bayesian beta-binomial model was used.

Study period: Influenza 2019-2020 season The investigators followed actively the pregnant women and their infants in order to collect prospectively data on a weekly basis through phone calls during the entire influenza season. Definitions: * ILI was defined as the sudden onset of symptoms and fever, malaise, myalgia or headache, and cough, sore throat or shortness of breath. * ARI was defined as the presence of at least one respiratory symptom, regardless of fever. * Febrile episode was defined as the presence of fever only. * Fever was defined as a temperature of 38.0 C in at least two measurements within 24h. * The diagnoses of pneumonia and AOM were accepted as reported by the physicians who provided care to the women or their infants. The 2019-2020 QIV Vaxigrip-Tetra was used to vaccinate pregnant women.

Conditions

Eligibility