Influenza epidemiology, vaccine coverage and vaccine effectiveness in children admitted to sentinel Australian hospitals in 2014: the Influenza Complications Alert Network (FluCAN)

Abstract

The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance programme operating in all states and territories in Australia. We summarise the epidemiology of children hospitalised with laboratory-confirmed influenza in 2014 and reports on the effectiveness of inactivated trivalent inactivated vaccine (TIV) in children. In this observational study, cases were defined as children admitted with acute respiratory illness (ARI) with influenza confirmed by PCR. Controls were hospitalised children with ARI testing negative for influenza. Vaccine effectiveness (VE) was estimated as 1 minus the odds ratio of vaccination in influenza positive cases compared with test-negative controls using conditional logistic regression models. From April until October 2014, 402 children were admitted with PCR-confirmed influenza. Of these, 28% were aged < 1 year, 16% were Indigenous, and 39% had underlying conditions predisposing to severe influenza. Influenza A was detected in 90% of cases of influenza; influenza A(H1N1)pdm09 was the most frequent subtype (109/141 of subtyped cases) followed by A(H3N2) (32/141). Only 15% of children with influenza received antiviral therapy. The adjusted VE of one or more doses of TIV for preventing hospitalised influenza was estimated at 55.5% (95% confidence intervals (CI): 11.6-77.6%). Effectiveness against influenza A(H1N1)pdm09 was high (91.6% , 95% CI: 36.0-98.9%) yet appeared poor against H3N2. In summary, the 2014 southern hemisphere TIV was moderately effective against severe influenza in children. Significant VE was observed against influenza A(H1N1)pdm09.

Vaccine‐preventable child deaths in New South Wales from 2005 to 2014: How much is preventable?

“…However, our conclusions are limited by the efficacy of the vaccines available for each disease. The estimated effectiveness of influenza vaccine in prevention of hospitalised influenza was 55.5% in a recent Australian study . Vaccine effectiveness against death was 65% (95% CI 54–74%) among children aged 6 months to 17 years in a recent US study, and 51% (95% CI 31–67%) in a subgroup of children with high‐risk conditions .…”

“…Previously healthy young children with influenza have been shown to have high hospital admission rates and may be more likely to die before hospital admission or within 3 days of symptom onset, compared to those with underlying medical conditions . While influenza vaccination is recommended in Australia for all children between 6 months and 5 years of age, it is only funded under the NIP for those at higher risk and coverage is very low . Coverage recorded in ACIR was less than 2.5% in children aged 6 months to less than 5 years of age between 2005 and 2014 (excluding Western Australia, where a funded seasonal influenza immunisation programme for children commenced in 2008) .…”

Prevalence of influenza A infection in the Middle‐East: A systematic review and meta‐analysis

“…In an investigation, Kuster et al reported incidence rates of influenza in vaccinated and unvaccinated HCWs were 6.5% and 18.7%, respectively . Children have the highest rate of influenza infection which led to hospitalization . The prevalence of influenza in children was reported 9.7%–29.0% based on the region by US influenza Surveillance Report .…”

“…Prevalence of influenza among Australian hospitals reported by Blyth et al They detected influenza A in 90% of 402 patients. Among the positive samples, H1N1, pdm09 and H3N2 were confirmed as a most frequent subtype . Epidemiological studies can be used for several purposes such as identify the dominant types of the virus to vaccination strategies for population and subgroups, identify high‐risk groups and identification of the epidemiological pattern of the disease.…”

“…94 Children have the highest rate of influenza infection which led to hospitalization. 95 The prevalence of influenza in children was reported 9.7%-29.0% based on the region by US influenza Surveillance Report. 96 Also, in our study prevalence of influenzas in children was, 29.4% and 24.6%.…”