Critical illness in children with influenza A/pH1N1 2009 infection in Canada*

Abstract

During the first outbreak of influenza A/pH1N1 infection, when the population was naïve to this novel virus, severe illness was common among children with underlying chronic conditions and aboriginal children. Influenza A/pH1N1-related critical illness in children was associated with severe hypoxemic respiratory failure and prolonged mechanical ventilation. However, this higher rate and severity of respiratory illness did not result in an increased mortality when compared with seasonal influenza.

Comparison of clinical presentation of respiratory tract infections in H1N1/09-positive and H1N1/09-negative patients

“…Moreover, in our epidemiological context, respiratory tract infections from causes other than H1N1/09 appeared more severe, as shown by a greater proportion of dyspnea, and a higher hospitalization rate in H1N1/09-negative children, associated with a greater proportion of wheezing episodes. H1N1/09 was recently associated with severe clinical syndromes in children, such as hypoxemic syndrome requiring mechanical ventilation [9], organ failure pattern [14], or even neurologic complications [2,21]. However, in other reports, when compared to seasonal influenza, pandemic H1N1/09 influenza did not appear to have a more severe course [1,3,17].…”

“…In our study, the prevalence of risk factors was significantly higher in H1N1/09-positive patients than in H1N1/09-negative patients and two thirds of our hospitalized H1N1/09-positive patients had a risk factor compared to only one third among outpatients. Similarly, in case series of hospitalized patients, risk factors-lung diseases being the most prevalent-were highly prevalent [12] and associated with a greater risk of severe disease [5], including that of being admitted to PICU [9]. In an outpatient setting, Mahut et al showed that ILI and severe exacerbation are significantly and strongly associated in the H1N1 influenza pandemic in asthmatic children [15].…”

“…Differences in studied populations and in screening and treatment strategies could explain differences in reported severity. Jouvet et al described that severe illness was common among aboriginal children [9]. Farias et al found a positive effect of oseltamivir on survival when it was administered within 24 h of admission to PICU [7], and Hiba et al demonstrate that early (<48 h) administration of oseltamivir could protect hospitalized adults from H1N1/09 complications [8].…”

Impact of H1N1 on socially disadvantaged populations: summary of a systematic review

“…After screening 787 titles and abstracts and 164 full‐text articles, 48 cohort studies plus 14 companion reports met eligibility criteria and were included 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73. These studies examined H1N1 between March 1, 2009 and October 24, 2010, and the most common factor of social disadvantage reported was ethnic minority status (36/48 studies), except in 12 studies that considered H1N1‐infected patients from LIC/LMIC, which were analyzed separately for each country (one study from Guatemala,57 two from Morocco,60, 61 one from Pakistan,73 and eight from India, plus four companion reports) 60, …”

Statement on Seasonal Influenza Vaccine for 2011–2012

“…However, an increased proportion of the Aboriginal community was noted to present with severe pH1N1 illness during the period of evaluation. An observational study (152) of 57 children admitted to nine Canadian PICUs with pH1N1 infection found that 14 (24.6%) of PICU patients were Aboriginal children, although Aboriginal people comprise only 3.8% of the Canadian population (15.5% in Manitoba). However, once hospitalized, Aboriginal children in this study were not at elevated risk for ICU admission.…”