tetano
Editor, Senior Moderator
Clin Infect Dis. 2017 May 5. doi: 10.1093/cid/cix420. [Epub ahead of print]
[h=1]Systematic review and meta-analysis of indirect protection afforded by vaccinating children against seasonal influenza: implications for policy.[/h] Yin JK[SUP]1,[/SUP][SUP]2,[/SUP][SUP]3[/SUP], Heywood AE[SUP]4[/SUP], Georgousakis M[SUP]1,[/SUP][SUP]2,[/SUP][SUP]3[/SUP], King C[SUP]1,[/SUP][SUP]2,[/SUP][SUP]5[/SUP], Chiu C[SUP]1,[/SUP][SUP]2,[/SUP][SUP]5[/SUP], Isaacs D[SUP]2,[/SUP][SUP]5[/SUP], Macartney KK[SUP]1,[/SUP][SUP]2,[/SUP][SUP]5[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] Universal childhood vaccination is a potential solution to reduce seasonal influenza burden.
[h=4]METHODS:[/h] We reviewed systematically the literature on 'herd'/indirect protection from vaccinating children aged 0?5-<18 years against influenza.
[h=4]RESULTS:[/h] Of 30 studies included, 14 (including one cluster-randomized-controlled trial [cRCT]) used live-attenuated-influenza-vaccine, 11 (seven cRCTs) used inactivated-influenza-vaccine, and five (one cRCT) compared both vaccine types. Twenty of 30 studies reported statistically significant indirect protection effectiveness (IPE) with point estimates ranging from 4-66%. Meta-regression suggests studies with high quality and/or sufficiently large sample size are more likely to report significant IPE. In meta-analyses of six cRCTs with full randomization (rated as moderate quality overall), significant IPE was found in one cRCT in closely connected communities where school-age children were vaccinated: 60% (95% confidence interval [CI] 41-72%; I2=0%; sample size=2,326) against laboratory-confirmed influenza, and three household cRCTs in which pre-school children were vaccinated: 22% (95% CI 1-38%; I2=0%; sample size=1,903) against acute respiratory infections or influenza-like illness. Significant IPE was also reported in a large-scaled cRCT (N=8,510) that was not fully randomized, and three ecological studies (sample size>10,000) of moderate quality including 36% reduction in influenza-related mortality among the elderly in the Japanese school-based program. Data on IPE in other settings are heterogeneous and lacked power to draw a firm conclusion.
[h=4]CONCLUSIONS:[/h] The available evidence suggests that influenza vaccination of children confers indirect protection in some but not all settings. Robust, large-scaled studies are required to quantify better the indirect protection from vaccinating children for different settings/endpoints.
[h=4]KEYWORDS:[/h] Seasonal influenza; children; immunization policy; indirect protection; influenza vaccine
PMID: 28475770 DOI: 10.1093/cid/cix420
[h=1]Systematic review and meta-analysis of indirect protection afforded by vaccinating children against seasonal influenza: implications for policy.[/h] Yin JK[SUP]1,[/SUP][SUP]2,[/SUP][SUP]3[/SUP], Heywood AE[SUP]4[/SUP], Georgousakis M[SUP]1,[/SUP][SUP]2,[/SUP][SUP]3[/SUP], King C[SUP]1,[/SUP][SUP]2,[/SUP][SUP]5[/SUP], Chiu C[SUP]1,[/SUP][SUP]2,[/SUP][SUP]5[/SUP], Isaacs D[SUP]2,[/SUP][SUP]5[/SUP], Macartney KK[SUP]1,[/SUP][SUP]2,[/SUP][SUP]5[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] Universal childhood vaccination is a potential solution to reduce seasonal influenza burden.
[h=4]METHODS:[/h] We reviewed systematically the literature on 'herd'/indirect protection from vaccinating children aged 0?5-<18 years against influenza.
[h=4]RESULTS:[/h] Of 30 studies included, 14 (including one cluster-randomized-controlled trial [cRCT]) used live-attenuated-influenza-vaccine, 11 (seven cRCTs) used inactivated-influenza-vaccine, and five (one cRCT) compared both vaccine types. Twenty of 30 studies reported statistically significant indirect protection effectiveness (IPE) with point estimates ranging from 4-66%. Meta-regression suggests studies with high quality and/or sufficiently large sample size are more likely to report significant IPE. In meta-analyses of six cRCTs with full randomization (rated as moderate quality overall), significant IPE was found in one cRCT in closely connected communities where school-age children were vaccinated: 60% (95% confidence interval [CI] 41-72%; I2=0%; sample size=2,326) against laboratory-confirmed influenza, and three household cRCTs in which pre-school children were vaccinated: 22% (95% CI 1-38%; I2=0%; sample size=1,903) against acute respiratory infections or influenza-like illness. Significant IPE was also reported in a large-scaled cRCT (N=8,510) that was not fully randomized, and three ecological studies (sample size>10,000) of moderate quality including 36% reduction in influenza-related mortality among the elderly in the Japanese school-based program. Data on IPE in other settings are heterogeneous and lacked power to draw a firm conclusion.
[h=4]CONCLUSIONS:[/h] The available evidence suggests that influenza vaccination of children confers indirect protection in some but not all settings. Robust, large-scaled studies are required to quantify better the indirect protection from vaccinating children for different settings/endpoints.
[h=4]KEYWORDS:[/h] Seasonal influenza; children; immunization policy; indirect protection; influenza vaccine
PMID: 28475770 DOI: 10.1093/cid/cix420