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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Influenza Vaccination Effectiveness of a Quadrivalent Inactivated Vaccine in Pregnant Women and Young Infants (Aged 6 Months and Below) During Influenza Season 2019/2020

Conditions
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Influenza in Human

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pregnant women >18 years old and <45 years old, cared at Alexandra General Hospital (Athens, Greece) between October 16 and January 27, 2020 Exclusion Criteria: <18 years old or >45 years old not in stable health already vaccinated against influenza history of Guillain-Barré syndrome history of hypersensitivity to influenza vaccines immunosuppression history of investigational drug <30 days history of immunoglobulins or blood products <3 months fever at day of interview (enrollment day)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| rates of laboratory-confirmed influenza in vaccinated and unvaccinated pregnant women | influenza vaccine effectiveness against laboratory-confirmed influenza in pregnant women | 2019-2020 influenza season | 
| rates of laboratory-confirmed influenza in young infants whose mothers were vaccinated and in infants of unvaccinated mothers | influenza vaccine effectiveness against laboratory-corfirmed influenza in young infants | 2019-2020 influenza season | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| rates of acute respiratory infection, influenza-like illness, febrile episode, use of antibiotics, use of antivirals, pneumonia, acute otitis media (for infants only), healthcare seeking and hospitalization in pregnant women and their infants | influenza vaccine effectiveness against the abovementioned secondary outcomes | 2019-2020 influenza season | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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influenza, quadrivalent influenza vaccine, influenza vaccine effectiveness, pregnancy, pregnant women, infants