%0 Journal Article
%T Incidence of laboratory-confirmed influenza disease among infants under 6 months of age: a systematic review
%A Becky Skidmore
%A Deshayne B Fell
%A Jeanene Johnson
%A Justin R Ortiz
%A Kathleen M Neuzil
%A Mark A Katz
%A Niranjan Bhat
%A Zohar Mor
%J -
%D 2017
%R 10.1136/bmjopen-2017-016526
%X Objectives The aim of this systematic review was to assess incidence rates of laboratory-confirmed influenza (LCI) outcomes among infants under 6£¿months of age.

Design Systematic literature search and review of indexed studies in PubMed, EMBASE, the Cochrane Library and CINAHL Plus from inception to 19 April 2017.

Setting Population-based estimates from community or hospital settings.

Participants Infants under 6£¿months of age.

Primary and secondary outcome measures LCI illness in ambulatory care settings, LCI hospitalisation, LCI intensive care unit admission and LCI death. Only studies with population-based incidence data were included.

Results We identified 27 primary studies, 11 of which were from the USA, four were from other non-US high-income settings and the remaining were from lower-middle-income or upper-middle-income countries. Most studies (n=23) assessed incidence of LCI hospitalisation, but meta-analysis to pool study-specific rates was not possible due to high statistical and methodological heterogeneity. Among US studies, the reported incidence of LCI hospitalisation ranged from 9.3 to 91.2 per 10£¿000 infants under 6£¿months for seasonal influenza, while the only US-based estimate for pandemic H1N1 influenza was 20.2 per 10£¿000 infants. Reported rates for LCI hospitalisation for seasonal influenza from other countries ranged from 6.2 to 73.0 per 10£¿000 infants under 6£¿months, with the exception of one study with an estimated rate of 250 per 10£¿000 infants. No events were reported in five of the nine studies that evaluated LCI death among infants under 6£¿months.

Conclusion Our review of published studies found limited data on LCI outcomes for infants under 6£¿months, particularly from non-US settings. Globally representative and reliable incidence data are necessary to fully evaluate influenza disease burden and the potential impact of maternal influenza immunisation programme on morbidity and mortality in young infants
%U https://bmjopen.bmj.com/content/7/9/e016526