Efficacy of live attenuated influenza vaccine in children: A meta-analysis of nine randomized clinical trials

Rhorer, Janelle; Ambrose, Christopher S.; Dickinson, Stephanie; Hamilton, Holli A.; Oleka, Napoleon; Malinoski, Frank; Wittes, Janet

doi:10.1016/j.vaccine.2008.11.093

Cited by 175 publications

(129 citation statements)

References 29 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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“…Nevertheless, vaccine efficacy was equally high for older children and younger children, and thus there was no suggestion that increasing levels of pre‐existing anti‐influenza immunity influenced LAIV efficacy. Data presented here and elsewhere 2 also suggest that LAIV efficacy does not decline in those previously vaccinated with LAIV; in fact, a trend toward increased efficacy with revaccination has been reported in a meta‐analysis of four 2‐year studies in children younger than 7 years of age 2 . Prior vaccination with TIV has also not been shown to impact LAIV efficacy relative to TIV; specifically, in study 2, the relative efficacy of LAIV compared with TIV against all strains regardless of antigenic match was similar in children aged 6–59 months who were previously vaccinated with TIV (51%) and those previously unvaccinated (57%) 20 .…”

Section: Discussionmentioning

confidence: 90%

“…Multiple prospective, randomized, controlled studies have described the efficacy of live attenuated influenza vaccine (LAIV) in children and adolescents compared with placebo and with trivalent inactivated influenza vaccine (TIV) 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 . LAIV provided levels of efficacy against influenza illness that, in the three comparative studies conducted, were significantly higher than those provided by TIV 1 , 3 , 7 .…”

Section: Introductionmentioning

confidence: 99%

Efficacy of live attenuated influenza vaccine in children 6 months to 17 years of age

Belshe

Toback²,

Yi³

et al. 2010

Influenza Resp Viruses

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Please cite this paper as: Belshe et al. (2010). Efficacy of live attenuated influenza vaccine in children 6 months to 17 years of age. Influenza and Other Respiratory Viruses 4(3), 141–145. Background It has been suggested that live attenuated influenza vaccine (LAIV) may be less effective in older individuals because of prior wild‐type influenza infections. LAIV is currently approved in the United States, South Korea and Hong Kong for individuals 2–49 years of age. Objective To examine data from previously published pediatric studies to determine the efficacy of LAIV in various age groups. Methods Four studies in which the subject age range exceeded 36 months were identified: one 2‐year study comparing LAIV with placebo and three 1‐year studies comparing LAIV with trivalent inactivated influenza vaccine (TIV). Efficacy against any strain regardless of antigenic similarity to vaccine was analyzed by age; age groups were based on the study design and sample size. A logistic regression model was used to assess whether age, as a continuous variable, was an effect modifier on LAIV efficacy. Results The efficacy of LAIV did not vary with age in children aged 15–84 months compared with placebo or in children aged 6 months to 17 years compared with TIV. Conclusions The available data from prospective, randomized studies in children does not support the concept that prior repeated exposure to influenza, either through wild‐type infection or vaccination with live, attenuated or inactivated vaccines, reduces the efficacy of LAIV compared with placebo or TIV. The decreased immunologic responses to LAIV reported in older individuals or those with pre‐existing immunity do not appear to translate into reduced protection from influenza in children.

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“…Moreover, because of intranasal administration, LAIV has the potential to stimulate greater local anti-influenza immune responses than TIV (20)(21)(22). LAIV demonstrated greater reductions in influenza than TIV in HIV-uninfected children, against strains that were well-matched with strains in the vaccine, as well as against antigenically drifted strains not included in the vaccine administered (23)(24)(25)(26)(27)(28), and several studies have shown that the LAIV protective effect can extend beyond the year of administration (27,28).…”

Section: Introductionmentioning

confidence: 99%

Shedding of live vaccine virus, comparative safety, and influenza-specific antibody responses after administration of live attenuated and inactivated trivalent influenza vaccines to HIV-infected children

Levin

Song

Fenton

et al. 2008

Vaccine

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Efficacy of live attenuated influenza vaccine in children: A meta-analysis of nine randomized clinical trials

Cited by 175 publications

References 29 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

Efficacy of live attenuated influenza vaccine in children 6 months to 17 years of age

Shedding of live vaccine virus, comparative safety, and influenza-specific antibody responses after administration of live attenuated and inactivated trivalent influenza vaccines to HIV-infected children

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