Epidemiological and clinical characteristics of childhood pandemic 2009 H1N1 virus infection: an observational cohort study

Abstract

BackgroundThere was a pandemic influenza around the world in 2009 including South Korea since last pandemic occurred four decades ago. We aimed to evaluate the epidemiological and clinical characteristics of this infection in childhood.MethodsWe evaluated the epidemiologic characteristics of all the subjects infected with the 2009 H1N1 influenza A virus (2,971 patients, ≤ 15 years of age), and the clinical and laboratory findings of the inpatients (217 patients, 80 had pneumonia) between 1 September 2009 and 31 January 2010 in a single hospital throughout the epidemic.ResultsThe age distribution of all the subjects was relatively even. Over 90% of cases occurred during a two-month period. Two hundred and five patients (94.5%) received oseltamivir within 48 h of fever onset, and 97% of inpatients defervesced within 48 h of medication. The group with pneumonia included more males than females, and had higher leukocytes counts with lower lymphocyte differentials than the group without pneumonia. The white blood cell count and lymphocyte differential were associated with the severity of pneumonia. Corticosteroid treatment for severe pneumonia patients was highly effective in preventing disease progression.ConclusionChildren of all ages affected with even rates of infection, but males were predominant in pneumonia patients. Pneumonia patients showed lymphopenia and its severity was associated with the severity of illness. Our results suggest that the mechanism of lung injury in 2009 H1N1 virus infection may be associated with the host immune response.

Genetic variation in chromosome Y regulates susceptibility to influenza A virus infection

“…For example, a 2010 report from the World Health Organization concluded that the outcomes of pandemic IAV, as well as of avian H5N1, are generally worse in females (3). However, in epidemiological studies in which age and sex were included as covariates, the data indicate that incidence and severity change as a function of age, with more males affected from birth through age 15 y and more females affected across all postpubertal age ranges (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Importantly, these data suggest that nonendocrine cell-intrinsic (genetic) sex-specific factors may contribute to disease susceptibility in males.…”

The value of radiographic findings for the progression of pandemic 2009 influenza A/H1N1 virus infection

“…This discrepancy may be explained by the fact that age distribution of A/H1N1 infection in children in Japan was toward school-aged children compared to infants and younger children [30]. Similar trends were observed in other Asian countries [31], suggesting that the influence of host genetic factors or the existence of maternal cross-reacting antibodies protected infants and younger children. Additionally, the use of NIs may contribute to the difference.…”

Cocoon Strategy of Vaccinations: Benefits and Limitations

“…The number of hospitalizations for inluenza in children at the age of up to 5 years amounts to 5/10,000 children and in adolescents, 1/10,000 persons [37]. A study by Rhim et al [38] demonstrated that 7.3% of children who reported to admission rooms in pediatric hospitals due to inluenza-like symptoms required hospitalization, whereas a study by Irving et al [39] showed that 5% of outpatients diagnosed with inluenza required hospitalizations.…”