Efficacy and effectiveness of influenza vaccines: A systematic review and meta-analysis

Michael T Osterholm, Nicholas S. Kelley, Alfred Sommer, Edward A. Belongia

Research output: Contribution to journalArticle

  • 899 Citations

Abstract

Background: No published meta-analyses have assessed efficacy and effectiveness of licensed influenza vaccines in the USA with sensitive and highly specific diagnostic tests to confirm influenza. Methods: We searched Medline for randomised controlled trials assessing a relative reduction in influenza risk of all circulating influenza viruses during individual seasons after vaccination (efficacy) and observational studies meeting inclusion criteria (effectiveness). Eligible articles were published between Jan 1, 1967, and Feb 15, 2011, and used RT-PCR or culture for confirmation of influenza. We excluded some studies on the basis of study design and vaccine characteristics. We estimated random-effects pooled efficacy for trivalent inactivated vaccine (TIV) and live attenuated influenza vaccine (LAIV) when data were available for statistical analysis (eg, at least three studies that assessed comparable age groups). Findings: We screened 5707 articles and identified 31 eligible studies (17 randomised controlled trials and 14 observational studies). Efficacy of TIV was shown in eight (67%) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 59% [95% CI 51-67] in adults aged 18-65 years). No such trials met inclusion criteria for children aged 2-17 years or adults aged 65 years or older. Efficacy of LAIV was shown in nine (75%) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 83% [69-91]) in children aged 6 months to 7 years. No such trials met inclusion criteria for children aged 8-17 years. Vaccine effectiveness was variable for seasonal influenza: six (35%) of 17 analyses in nine studies showed significant protection against medically attended influenza in the outpatient or inpatient setting. Median monovalent pandemic H1N1 vaccine effectiveness in five observational studies was 69% (range 60-93). Interpretation: Influenza vaccines can provide moderate protection against virologically confirmed influenza, but such protection is greatly reduced or absent in some seasons. Evidence for protection in adults aged 65 years or older is lacking. LAIVs consistently show highest efficacy in young children (aged 6 months to 7 years). New vaccines with improved clinical efficacy and effectiveness are needed to further reduce influenza-related morbidity and mortality. Funding: Alfred P Sloan Foundation.

LanguageEnglish (US)
Pages36-44
Number of pages9
JournalThe Lancet Infectious Diseases
Volume12
Issue number1
DOIs
StatePublished - Jan 1 2012

Fingerprint

Influenza Vaccines
Human Influenza
Meta-Analysis
Attenuated Vaccines
Vaccines
Randomized Controlled Trials
Observational Studies
Inactivated Vaccines
Pandemics
Orthomyxoviridae
Routine Diagnostic Tests
Inpatients
Vaccination
Outpatients
Age Groups
Morbidity
Polymerase Chain Reaction
Mortality

Cite this

Efficacy and effectiveness of influenza vaccines : A systematic review and meta-analysis. / Osterholm, Michael T; Kelley, Nicholas S.; Sommer, Alfred; Belongia, Edward A.

In: The Lancet Infectious Diseases, Vol. 12, No. 1, 01.01.2012, p. 36-44.

Research output: Contribution to journalArticle

Osterholm, Michael T ; Kelley, Nicholas S. ; Sommer, Alfred ; Belongia, Edward A. / Efficacy and effectiveness of influenza vaccines : A systematic review and meta-analysis. In: The Lancet Infectious Diseases. 2012 ; Vol. 12, No. 1. pp. 36-44.
@article{872cd3e5583e4af589a7bc7a3b383fc3,
title = "Efficacy and effectiveness of influenza vaccines: A systematic review and meta-analysis",
abstract = "Background: No published meta-analyses have assessed efficacy and effectiveness of licensed influenza vaccines in the USA with sensitive and highly specific diagnostic tests to confirm influenza. Methods: We searched Medline for randomised controlled trials assessing a relative reduction in influenza risk of all circulating influenza viruses during individual seasons after vaccination (efficacy) and observational studies meeting inclusion criteria (effectiveness). Eligible articles were published between Jan 1, 1967, and Feb 15, 2011, and used RT-PCR or culture for confirmation of influenza. We excluded some studies on the basis of study design and vaccine characteristics. We estimated random-effects pooled efficacy for trivalent inactivated vaccine (TIV) and live attenuated influenza vaccine (LAIV) when data were available for statistical analysis (eg, at least three studies that assessed comparable age groups). Findings: We screened 5707 articles and identified 31 eligible studies (17 randomised controlled trials and 14 observational studies). Efficacy of TIV was shown in eight (67{\%}) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 59{\%} [95{\%} CI 51-67] in adults aged 18-65 years). No such trials met inclusion criteria for children aged 2-17 years or adults aged 65 years or older. Efficacy of LAIV was shown in nine (75{\%}) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 83{\%} [69-91]) in children aged 6 months to 7 years. No such trials met inclusion criteria for children aged 8-17 years. Vaccine effectiveness was variable for seasonal influenza: six (35{\%}) of 17 analyses in nine studies showed significant protection against medically attended influenza in the outpatient or inpatient setting. Median monovalent pandemic H1N1 vaccine effectiveness in five observational studies was 69{\%} (range 60-93). Interpretation: Influenza vaccines can provide moderate protection against virologically confirmed influenza, but such protection is greatly reduced or absent in some seasons. Evidence for protection in adults aged 65 years or older is lacking. LAIVs consistently show highest efficacy in young children (aged 6 months to 7 years). New vaccines with improved clinical efficacy and effectiveness are needed to further reduce influenza-related morbidity and mortality. Funding: Alfred P Sloan Foundation.",
author = "Osterholm, {Michael T} and Kelley, {Nicholas S.} and Alfred Sommer and Belongia, {Edward A.}",
year = "2012",
month = "1",
day = "1",
doi = "10.1016/S1473-3099(11)70295-X",
language = "English (US)",
volume = "12",
pages = "36--44",
journal = "The Lancet Infectious Diseases",
issn = "1473-3099",
publisher = "Lancet Publishing Group",
number = "1",

}

TY - JOUR

T1 - Efficacy and effectiveness of influenza vaccines

T2 - The Lancet Infectious Diseases

AU - Osterholm, Michael T

AU - Kelley, Nicholas S.

AU - Sommer, Alfred

AU - Belongia, Edward A.

PY - 2012/1/1

Y1 - 2012/1/1

N2 - Background: No published meta-analyses have assessed efficacy and effectiveness of licensed influenza vaccines in the USA with sensitive and highly specific diagnostic tests to confirm influenza. Methods: We searched Medline for randomised controlled trials assessing a relative reduction in influenza risk of all circulating influenza viruses during individual seasons after vaccination (efficacy) and observational studies meeting inclusion criteria (effectiveness). Eligible articles were published between Jan 1, 1967, and Feb 15, 2011, and used RT-PCR or culture for confirmation of influenza. We excluded some studies on the basis of study design and vaccine characteristics. We estimated random-effects pooled efficacy for trivalent inactivated vaccine (TIV) and live attenuated influenza vaccine (LAIV) when data were available for statistical analysis (eg, at least three studies that assessed comparable age groups). Findings: We screened 5707 articles and identified 31 eligible studies (17 randomised controlled trials and 14 observational studies). Efficacy of TIV was shown in eight (67%) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 59% [95% CI 51-67] in adults aged 18-65 years). No such trials met inclusion criteria for children aged 2-17 years or adults aged 65 years or older. Efficacy of LAIV was shown in nine (75%) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 83% [69-91]) in children aged 6 months to 7 years. No such trials met inclusion criteria for children aged 8-17 years. Vaccine effectiveness was variable for seasonal influenza: six (35%) of 17 analyses in nine studies showed significant protection against medically attended influenza in the outpatient or inpatient setting. Median monovalent pandemic H1N1 vaccine effectiveness in five observational studies was 69% (range 60-93). Interpretation: Influenza vaccines can provide moderate protection against virologically confirmed influenza, but such protection is greatly reduced or absent in some seasons. Evidence for protection in adults aged 65 years or older is lacking. LAIVs consistently show highest efficacy in young children (aged 6 months to 7 years). New vaccines with improved clinical efficacy and effectiveness are needed to further reduce influenza-related morbidity and mortality. Funding: Alfred P Sloan Foundation.

AB - Background: No published meta-analyses have assessed efficacy and effectiveness of licensed influenza vaccines in the USA with sensitive and highly specific diagnostic tests to confirm influenza. Methods: We searched Medline for randomised controlled trials assessing a relative reduction in influenza risk of all circulating influenza viruses during individual seasons after vaccination (efficacy) and observational studies meeting inclusion criteria (effectiveness). Eligible articles were published between Jan 1, 1967, and Feb 15, 2011, and used RT-PCR or culture for confirmation of influenza. We excluded some studies on the basis of study design and vaccine characteristics. We estimated random-effects pooled efficacy for trivalent inactivated vaccine (TIV) and live attenuated influenza vaccine (LAIV) when data were available for statistical analysis (eg, at least three studies that assessed comparable age groups). Findings: We screened 5707 articles and identified 31 eligible studies (17 randomised controlled trials and 14 observational studies). Efficacy of TIV was shown in eight (67%) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 59% [95% CI 51-67] in adults aged 18-65 years). No such trials met inclusion criteria for children aged 2-17 years or adults aged 65 years or older. Efficacy of LAIV was shown in nine (75%) of the 12 seasons analysed in ten randomised controlled trials (pooled efficacy 83% [69-91]) in children aged 6 months to 7 years. No such trials met inclusion criteria for children aged 8-17 years. Vaccine effectiveness was variable for seasonal influenza: six (35%) of 17 analyses in nine studies showed significant protection against medically attended influenza in the outpatient or inpatient setting. Median monovalent pandemic H1N1 vaccine effectiveness in five observational studies was 69% (range 60-93). Interpretation: Influenza vaccines can provide moderate protection against virologically confirmed influenza, but such protection is greatly reduced or absent in some seasons. Evidence for protection in adults aged 65 years or older is lacking. LAIVs consistently show highest efficacy in young children (aged 6 months to 7 years). New vaccines with improved clinical efficacy and effectiveness are needed to further reduce influenza-related morbidity and mortality. Funding: Alfred P Sloan Foundation.

UR - http://www.scopus.com/inward/record.url?scp=84155162558&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84155162558&partnerID=8YFLogxK

U2 - 10.1016/S1473-3099(11)70295-X

DO - 10.1016/S1473-3099(11)70295-X

M3 - Article

VL - 12

SP - 36

EP - 44

JO - The Lancet Infectious Diseases

JF - The Lancet Infectious Diseases

SN - 1473-3099

IS - 1

ER -