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

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

doi:10.1016/s1473-3099(11)70295-x

Cited by 1,549 publications

(1,220 citation statements)

References 58 publications

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“…The protection in children (range 20–77%) and in healthy adults (range 50–59%) seen in the tropics and subtropics was comparable with that seen in developed countries 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74. Vaccine protection studies from the tropics and subtropics faced certain limitations.…”

Section: Discussionsupporting

confidence: 57%

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics – a systematic literature review

Hirve

Lambach

Paget

et al. 2016

Influenza Resp Viruses

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AimThe evidence needed for tropical countries to take informed decisions on influenza vaccination is scarce. This article reviews policy, availability, use and effectiveness of seasonal influenza vaccine in tropical and subtropical countries.MethodGlobal health databases were searched in three thematic areas – policy, availability and protective benefits in the context of human seasonal influenza vaccine in the tropics and subtropics. We excluded studies on monovalent pandemic influenza vaccine, vaccine safety, immunogenicity and uptake, and disease burden.ResultsSeventy‐four countries in the tropics and subtropics representing 60% of the world's population did not have a national vaccination policy against seasonal influenza. Thirty‐eight countries used the Northern Hemisphere and 21 countries the Southern Hemisphere formulation. Forty‐six countries targeted children and 57 targeted the elderly; though, the age cut‐offs varied. Influenza vaccine supply increased twofold in recent years. However, coverage remained lower than five per 1000 population. Vaccine protection against laboratory‐confirmed influenza in the tropics ranged from 0% to 42% in the elderly, 20–77% in children and 50–59% in healthy adults. Vaccinating pregnant women against seasonal influenza prevented laboratory‐confirmed influenza in both mothers (50%) and their infants <6 months (49–63%).ConclusionGuidelines on vaccine composition, priority risk groups and vaccine availability varied widely. The evidence on vaccine protection was scarce. Countries in the tropics and subtropics need to strengthen and expand their evidence‐base required for making informed decisions on influenza vaccine introduction and expansion, and how much benefit to expect.

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Section: Discussionsupporting

confidence: 57%

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics – a systematic literature review

Hirve

Lambach

Paget

et al. 2016

Influenza Resp Viruses

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“…For children younger than 3 years, there is inconsistent evidence on the efficacy and effectiveness of seasonal inactivated vaccines 24, 25. Efficacy in this age group cannot be assumed for existing vaccines and cannot therefore be deduced from comparative immunogenicity studies.…”

Section: How To Establish Clinical Efficacy In the Post‐chmp Criteriamentioning

confidence: 99%

“…Hence, the proposed guideline requires applicants to conduct randomized controlled trials with clinical endpoints in order to conclude efficacy for children aged 6 months to 3 years. For children between the ages of 3–6 years, there is some evidence to support efficacy of inactivated influenza vaccines, albeit being moderate 24, 25, 26. Yet the proposed guideline states that as the proportion of children up to the age of approximately 9 years who are immunologically primed is thought to be variable, efficacy can be deduced from demonstrating a non‐inferior immune response to the youngest children for whom efficacy against clinical endpoints should have been demonstrated.…”

Section: How To Establish Clinical Efficacy In the Post‐chmp Criteriamentioning

confidence: 99%

A review of the changes to the licensing of influenza vaccines in Europe

Wijnans

Voordouw

2015

Influenza Resp Viruses

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In 2014, the European Committee for Medicinal Products for Human Use (CHMP) published a draft regulatory guideline for the evaluation of influenza vaccines. Following a public consultation round, the final guidance will be published in the near future. Here, we highlight the main changes in the clinical section in this guideline and discuss the background to these changes and whether the new consolidated guidance document can be expected to achieve a better understanding of the performance of seasonal, zoonotic and pandemic influenza vaccines during the regulatory licensing process. The new influenza guideline reflects a changed approach to the regulatory assessment of influenza vaccines, resulting in the abolition of serological criteria, known as the CHMP criteria, which have been the mainstay for evaluating the influenza vaccine immunogenicity for several decades. The new guideline adopts a more diversified approach to the measurement and reporting of the immune response to influenza vaccines and sets a requirement to conduct clinical outcome trials in young children. Importantly, more emphasis is placed on the post‐licensure monitoring of the benefit risk of influenza vaccines, including a request for continuous monitoring of efficacy and enhanced safety surveillance. Despite the improvements these new requirements will expectedly bring to the regulatory assessment of influenza vaccines, major challenges remain which cannot be overcome by new guidance alone. Ongoing initiatives in which academia, manufacturers, public health institutes and regulators work together to address these challenges are central to the development of robust tools to evaluate and monitor performance of influenza vaccines in the future.

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“…However, effectiveness rates vary, averaging around 50-60%. 4,5 More recently, live attenuated influenza vaccine (LAIV) was demonstrated to have greater efficacy than IIV in children, with absolute efficacy rates of 75-80%. [6][7][8] Internal genes of LAIV viruses are derived from a cold-adapted, attenuated strain of virus, either Ann Arbor/1960 (from the US) or Leningrad/1957 (from Russia).…”

Section: Introductionmentioning

confidence: 99%

Urgent challenges in implementing live attenuated influenza vaccine

Singanayagam

Zambon

Lalvani

et al. 2018

The Lancet Infectious Diseases

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SummaryConflicting reports have emerged about the effectiveness of the live attenuated influenza vaccine (LAIV). LAIV appears to be protecting particularly poorly against currently circulating H1N1 viruses that are derived from the 2009 pandemic H1N1 (pH1N1) viruses. During the 2015/16 influenza season, when pH1N1 was the predominant virus, studies from the United States (US) reported a complete lack of effectiveness of LAIV in children. This led to a critical decision in the US to recommend that LAIV not be used in 2016/17 and to switch to the inactivated influenza vaccine. Other countries, including the UK, Canada and Finland, have continued to recommend use of LAIV. This policy divergence and uncertainty has far reaching implications for the entire global community, given the importance of LAIV production capability for pandemic preparedness. In this Personal View, we discuss possible explanations for the observed reduced effectiveness of LAIV and highlight underpinning scientific questions. Further research to understand the reasons for these observations is essential to enable informed public health policy and commercial decisions about vaccine production and development in coming years. 3 IntroductionInfluenza vaccination remains the main strategy to control the burden of seasonal influenza disease that affects 5-10% of adults and 20-30% of children, resulting in 250,000-500,000 deaths worldwide each year. 1,2 In the US, 140 million doses of vaccine are distributed each year and vaccination is estimated to prevent nearly a quarter of predicted influenza-associated deaths. 3 Vaccination is also the primary public health response to a global influenza pandemic.Influenza vaccines contain a mixture of three or four components designed to protect against the different viruses that circulate contemporaneously as seasonal influenza viruses. Currently, these are two influenza A viruses (H1N1 and H3N2 subtypes) and two influenza B viruses (Victoria and Yamagata lineages). Vaccine components are reviewed and updated regularly by the WHO in line with observed antigenic drift of influenza viruses.The traditional inactivated influenza vaccine (IIV) was introduced in the 1940s. IIV is administered by intramuscular/intradermal injection, is licensed for use in all ages and has a good safety record. However, effectiveness rates vary, averaging around 50-60%. 4,5 More recently, live attenuated influenza vaccine (LAIV) was demonstrated to have greater efficacy than IIV in children, with absolute efficacy rates of 75-80%. [6][7][8] Internal genes of LAIV viruses are derived from a cold-adapted, attenuated strain of virus, either Ann Arbor/1960 (from the US) or Leningrad/1957 (from Russia). Haemagglutinin (HA) and neuraminidase (NA) surface antigens are engineered to be representative of currently circulating strains. LAIV is nasally administered and vaccine viruses replicate only in the air-cooled environment of the human upper respiratory tract. This results in a mild and self-limiting infection; virus cannot replicate at t...

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

Cited by 1,549 publications

References 58 publications

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics – a systematic literature review

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics – a systematic literature review

A review of the changes to the licensing of influenza vaccines in Europe

Urgent challenges in implementing live attenuated influenza vaccine

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