Epidemiological analysis of severe hospitalized 2009 pandemic influenza A (H1N1) cases in Catalonia, Spain

Obesity and respiratory infections: Does excess adiposity weigh down host defense?

“…Additional studies confirmed these associations indicating that obesity and morbid obesity were independent risk factors for hospitalization 26 , admission to an intensive care unit 27 , and critical illness and death 23, 28 associated with H1N1 infection in the US 29 . Similar reports from many other countries also indicate a greater severity of illness and death from pandemic H1N1 in obese patients 30-35 (Summarized in Table 1). While this information suggests that obese individuals should receive annual seasonal influenza vaccinations, obesity is associated with a greater decline in influenza vaccine antibody titers and defective influenza-specific CD8+T cell function 36 .…”

Subjects Hospitalized With the 2009 Pandemic Influenza A (H1N1) Virus in a Respiratory Infection Unit: Clinical Factors Correlating With ICU Admission

“…Our data are in accordance with previous studies showing that younger adults are more often hospitalized. [14][15][16] This could probably be attributed to the fact that older people are partially protected by the presence of pre-existing antibodies from natural exposure to the A (H1N1) strains that circulated in the year following 1918 or to vaccine- induced cross-reactivity. [17][18][19] Although several studies have shown that current and past pandemics affected mainly younger adults, 20,21 with patients younger than 50 y having a higher risk of death, 22 in a recent meta-analysis, a significant increase in the risk of hospitalization and death was found in elderly compared with non-elderly subjects, but this risk was associated with the existence of comorbidities.…”

“…23 Multivariate analyses in several studies confirmed that the presence of concomitant diseases strictly related to age and probably not independent of it might represent a greater risk factor for ICU admission and death. [14][15][16] Forty-two percent of the subjects in our sample who were hospitalized had at least one comorbidity, with the most common conditions being asthma (19 cases, 17%) and COPD (10 cases, 9%), whereas the remaining subjects had no comorbidities. This finding is in agreement with worldwide clinical data on 2009 H1N1 virus infection, which show that 25-50% of 2009 H1N1 patients who were hospitalized or died had no underlying comorbidities.…”

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

“…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].…”