A Systematic Review of Studies of the Effect of Influenza Vaccine Against Mismatched Strains

Study Overview
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Brief Summary
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The purpose of this study is to consolidate the cross-protection offered by influenza vaccines against circulating influenza A or B viruses that are not antigenically well-matched to vaccine strains and to determine the degree of cross-protection separately for influenza A and influenza B, through a systematic review of the literature.

Detailed Description
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The research question of this project is: what is the cross-protection afforded by vaccination (using an LAIV, TIV, or other type of vaccine) against influenza A or B and their subtypes and lineages? The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Statement will be used to guide the reporting of this review. Studies reporting cross-protection data after vaccination with approved formulations of influenza vaccines with influenza A or B will be included. Inclusion will not be limited by publication status, or year of dissemination but will be limited to randomized clinical trials (RCTs) and quasi-RCTs comparing influenza vaccine(s) with placebo. Only RCTs written in English will be included. A meta-analysis will be conducted if there is sufficient data.

Official Title
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Effect of Influenza Vaccine Against Mismatched Strains: Systematic Review

Conditions
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Influenza

Intervention / Treatment
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* Biological: Vaccines


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy children, adults or the elderly will be included that participated in randomized clinical trials (RCTs) and quasi-RCTs comparing influenza vaccine(s) with placebo. Placebo-controlled randomized clinical trials (RCTs) reporting laboratory-confirmed influenza among healthy participants vaccinated with antigens of influenza strains that differed from those circulating. All influenza vaccines will be included, and will be categorized as TIV, LAIV, and others (that is, non-TIV or non-LAIV). Only RCTs written in English will be included. Exclusion Criteria: RCTs which are not providing any data will be excluded. Studies using rapid influenza diagnostic tests will not be included, as their sensitivity is low (especially during flu season) and false positives are common during low activity seasons. Laboratory-confirmed influenza through antibody assay as part of the primary outcome will not be included, as this is a less sensitive test than PCR and viral culture.
Sexes Eligible for Study
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All

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cross-Protection Studies<br> | Biological: Vaccines<br>* Unadjuvanted, monovalent, and trivalent vaccines, and vaccines delivered intramuscularly, intradermally, or intranasally, depending on what is found in the included studies.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of laboratory-confirmed influenza [Polymerase Chain Reaction (PCR) or viral culture]. |  |  | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of laboratory-confirmed influenza through antibody assay (a less sensitive test than PCR or viral culture), alone or combined with PCR, and/or viral culture. |  |  | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Influenza, Systematic review, Meta-analysis, Mismatched strains, Cross-protection