Mortality risk greater for children hospitalized with influenza B vs. influenza A
Although morbidity rates for children hospitalized with influenza A and B infections were similar, those with influenza B had twice the risk for influenza-attributed death and should be targeted for vaccination, according to results of a Canadian study.
“To date, influenza B has been less researched than influenza A, partly because influenza A is capable of causing pandemics, and partly because influenza B is considered less virulent,” Dat Tran, MD, MSc, assistant professor of pediatrics at the University of Toronto, and colleagues wrote. “However, there is increasing recognition of the substantial impact of influenza B and the need to characterize differences in outcomes between influenza A and B.”
To examine these differences, Tran and colleagues analyzed patient data from the Canadian Immunization Monitoring Program Active at 12 pediatric Canadian hospitals. More than eight nonpandemic influenza seasons occurred during the 10-year observational period, resulting in 1,510 patients hospitalized with influenza B (mean age, 3.9 years) and 2,645 patients with influenza A (mean age, 2 years). The researchers compared clinical traits and outcomes of patients, aged no older than 16 years, admitted with laboratory-confirmed infections to ICUs.
When adjusted for health status and age, patients admitted for influenza B were more likely to have a vaccine-indicated condition (OR = 1.3; 95% CI, 1.14-1.47) vs. those admitted for influenza A. Patients with influenza B also were at greater risk for headache, abdominal pain and myalgia (P < .0001 for all). Further, those aged at least 10 years with influenza B, but otherwise healthy, exhibited the greatest odds for ICU admission (OR = 5.79; 95% CI, 1.91-17.57).
Deaths attributed to influenza B occurred in 1.1% of the cohort, compared with 0.4% of admitted patients with influenza A (adjusted OR = 2.65; 95% CI, 1.18-5.94).
“Among hospitalized children [with influenza A and B infections] … mortality was greater for influenza B disease,” the researchers concluded. “Among healthy children hospitalized with influenza B, those aged 10 to 16 years were most likely to require ICU admission.
“These children should be considered at high risk for complicated influenza B infection and be specifically targeted by immunization programs to receive influenza vaccination, and in particular, a [quadrivalent influenza vaccine].” – by Kate Sherrer
Disclosure: The researchers report no relevant financial disclosures.