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. 2018 Apr 11;217(9):1365-1371.
doi: 10.1093/infdis/jiy027.

Influenza Vaccine Effectiveness Against Influenza A(H3N2) Hospitalizations in Children in Hong Kong in a Prolonged Season, 2016/2017

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Influenza Vaccine Effectiveness Against Influenza A(H3N2) Hospitalizations in Children in Hong Kong in a Prolonged Season, 2016/2017

Susan S Chiu et al. J Infect Dis. .

Abstract

Background: Influenza A(H3N2) viruses circulated for 12 consecutive months in Hong Kong in 2016-2017, peaking in late June and July 2017. The objective of our study was to estimate the effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong.

Methods: We conducted a test-negative study between 1 September 2016 and 31 August 2017, enrolling children 6 months to 17 years of age hospitalized for an acute respiratory infection. Influenza was diagnosed by PCR on nasopharyngeal aspirates.

Results: We enrolled 5514 children, including 3608 children 6 months to 2 years, 1600 children 3-5 years, and 1206 children 6-17 years of age. Influenza-associated hospitalizations occurred throughout the study year but time of vaccination of these children was also wide spread, from September 2016 to May 2017. Influenza vaccine effectiveness (VE) was 39.7% (95% confidence interval [CI], 14.7%-57.3%) against laboratory-confirmed influenza A(H3N2). In analyses stratified by time since vaccination, the VE against influenza A(H3N2) was 52.8% (95% CI, 17.1%-73.2%) within 3 months of vaccination, and 31.2% (95% CI, -6.6% to 55.6%) 4-6 months after vaccination.

Conclusions: Influenza vaccination was effective in preventing hospitalizations in children in Hong Kong.

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Figures

Figure 1.
Figure 1.
Timeline of recruitment of cases testing positive or negative for influenza virus by type/subtype in Hong Kong, September 2016 to August 2017.
Figure 2.
Figure 2.
Estimated influenza vaccine effectiveness against influenza A or B among children in Hong Kong by age group, September 2016 to August 2017. Abbreviation: Vax, vaccinated.
Figure 3.
Figure 3.
Estimated influenza vaccine effectiveness against influenza A(H3N2) among children in Hong Kong by age group and phase of hospitalization, September 2016 to August 2017. A, Two-phase analysis: early phase was defined as 1 September 2016 to 28 February 2017; and late phase, 1 March to 31 August 2017. B, Three-phase analysis: phase I was defined as 1 September to 31 December 2016; phase II, 1 January to 30 April 2017; and phase III, 1 May to 31 August 2017. Results for confidence intervals wider than 500% are not shown.
Figure 4.
Figure 4.
Estimated influenza vaccine effectiveness against influenza A or B among children in Hong Kong by age group and phase of hospitalization, September 2016 to August 2017. A, Two-phase analysis: early phase was defined as 1 September 2016 to 28 February 2017; and late phase, 1 March to 31 August 2017. B, Three-phase analysis: phase I was defined as 1 September to 31 December 2016; phase II, 1 January to 30 April 2017; and phase III, 1 May to 31 August 2017. Results for confidence intervals wider than 500% were not shown.
Figure 5.
Figure 5.
Estimated influenza vaccine effectiveness against influenza A(H3N2) among children in Hong Kong by age group and interval since vaccination (Vac; vaccinated from 14 days to 3 months versus 4 to 6 months), September 2016 to August 2017.

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References

    1. Chiu SS, Feng S, Chan KH et al. . Hospital-based vaccine effectiveness against influenza B lineages, Hong Kong, 2009-14. Vaccine 2016; 34:2164–9. - PubMed
    1. Chiu SS, Chan KH, Chen H et al. . Virologically confirmed population-based burden of hospitalization caused by influenza A and B among children in Hong Kong. Clin Infect Dis 2009; 49:1016–21. - PubMed
    1. Chiu SS, Lau YL, Chan KH, Wong WH, Peiris JS. Influenza-related hospitalizations among children in Hong Kong. N Engl J Med 2002; 347:2097–103. - PubMed
    1. Cowling BJ, Chan KH, Feng S et al. . The effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong, 2009-2013. Vaccine 2014; 32:5278–84. - PMC - PubMed
    1. Uyeki TM. Preventing and controlling influenza with available interventions. N Engl J Med 2014; 370:789–91. - PMC - PubMed

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