Clinical trial NCT04723771: Influenza Vaccine Effectiveness of a Quadrivalent Vaccine in Pregnant Women and Young Infants, 2019-2020
Official title: Influenza Vaccination Effectiveness of a Quadrivalent Inactivated Vaccine in Pregnant Women and Young Infants (Aged 6 Months and Below) During Influenza Season 2019/2020
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Influenza in Human
Keywords: influenza
quadrivalent influenza vaccine
influenza vaccine effectiveness
pregnancy
pregnant women
infants
Lead sponsor: University of Athens
Sponsor class: OTHER
Collaborators: name: Hellenic Pasteur Institute
First posted: 2021-01-26
Enrollment: 949
Sex: FEMALE
Minimum age (years): 18
Maximum age (years): 45
Standard ages: ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Pregnant women and their infants

Brief summary: 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: 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.

Eligibility criteria: 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)

Primary outcomes:
measure: rates of laboratory-confirmed influenza in vaccinated and unvaccinated pregnant women
timeFrame: 2019-2020 influenza season
measure: rates of laboratory-confirmed influenza in young infants whose mothers were vaccinated and in infants of unvaccinated mothers
timeFrame: 2019-2020 influenza season
Secondary outcomes:
measure: 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
timeFrame: 2019-2020 influenza season
Other outcomes:
Locations:
city: Athens
country: Greece
facility: First Department of Obstetrics and Gynecology, University of Athens
state: Attica
Study officials:
affiliation: First Department of Obstetrics and Gynecology, University of Athens
name: Dimitrios Loutradis, Professor
role: PRINCIPAL_INVESTIGATOR
References:
citation: 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.