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

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

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 Overview

• Status: Completed
• Conditions: Influenza in Human

Detailed Description

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.

• Study Type: Observational
• Enrollment (Actual): 949

Contacts and Locations

Study Locations

• Greece
  • Attica
    • Athens, Attica, Greece
      • First Department of Obstetrics and Gynecology, University of Athens

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 45 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

• Sampling Method: Non-Probability Sample

Study Population

Pregnant women and their infants

Description

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)

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: University of Athens
• Collaborators: Hellenic Pasteur Institute
• Investigators: Principal Investigator: Dimitrios Loutradis, Professor, First Department of Obstetrics and Gynecology, University of Athens

Publications and helpful links

General Publications

• Maltezou HC, Stavros S, Asimakopoulos G, Pergialiotis V, Raftopoulos V, Talias MA, Pavli A, Daskalakis G, Sindos M, Koutroumanis P, Theodora M, Antsaklis P, Kostis E, Stratiki E, Kossyvakis A, Theodoridou M, Mentis A, Drakakis P, Loutradis D, Rodolakis A. Effectiveness of maternal vaccination with quadrivalent inactivated influenza vaccine in pregnant women and their infants in 2019-2020. Expert Rev Vaccines. 2022 Jul;21(7):983-992. doi: 10.1080/14760584.2022.2013820. Epub 2022 Jan 24.

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2019
• Primary Completion (Actual): April 30, 2020
• Study Completion (Actual): August 31, 2020

Study Registration Dates

• First Submitted: September 22, 2020
• First Submitted That Met QC Criteria: January 20, 2021
• First Posted (Actual): January 26, 2021

Study Record Updates

• Last Update Posted (Actual): May 11, 2021
• Last Update Submitted That Met QC Criteria: May 6, 2021
• Last Verified: May 1, 2021

More Information

Terms related to this study

• Keywords: influenza; quadrivalent influenza vaccine; influenza vaccine effectiveness; pregnancy; pregnant women; infants
• Additional Relevant MeSH Terms: RNA Virus Infections; Virus Diseases; Infections; Respiratory Tract Infections; Respiratory Tract Diseases; Orthomyxoviridae Infections; Influenza, Human
• Other Study ID Numbers: 16708

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided
• IPD Plan Description: In order to share IPD we should request permission from the Ethics Committee of the hospital.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No