Surveillance of Hospitalisations for 2009 Pandemic Influenza A(H1N1) in the Netherlands, 5 June – 31 December 2009

Abstract

We analysed and reported on a weekly basis clinical and epidemiological characteristics of patients hospitalised in the Netherlands for the 2009 pandemic influenza A(H1N1) using information from the national mandatory notification system. The notification criteria changed on 15 August 2009 from all possible, probable and confirmed cases to only laboratory-confirmed pandemic influenza hospitalisations and deaths. In the period of comprehensive case-based surveillance (until 15 August), 2% (35/1,622) of the patients with pandemic influenza were hospitalised. From 5 June to 31 December 2009, a total of 2,181 patients were hospitalised. Of these, 10% (219/2,181) were admitted to an intensive care unit (ICU) and 53 died. Among non-ICU hospitalised patients, 56% (961/1,722) had an underlying medical condition compared with 70% (147/211) of the patients in ICU and 46 of the 51 fatal cases for whom this information was reported. Most common complications were dehydration among non-ICU hospitalised patients and acute respiratory distress syndrome among patients in ICU and patients who died. Children under the age of five years had the highest age-specific hospitalisation rate (62.7/100,000), but relatively few were admitted to an ICU (1.7/100,000). Characteristics and admission rates of hospitalised patients were comparable with reports from other countries and previous influenza seasons. The national notification system was well suited to provide weekly updates of relevant monitoring information on the severity of the pandemic for professionals, decision makers, the media and the public, and could be rapidly adapted to changing information requirements.

Pandemic influenza hospitalization in Spain (2009): Incidence, in-hospital mortality, comorbidities and costs

“…Regarding the incidence of hospitalization, our data are consistent with other published results, showing that people under 15 had the highest incidence [12][13][14] in contrast to seasonal influenza, were the highest the authors used data from the MBDS database recorded between July 1 and December 31, 2009. Demographic data analyzed included age and sex.…”

“…[11][12][13] Across the MBDS, patients with a chronic liver disease presented the highest IHM rate, followed by patients with a neurological disease and neoplasm.…”

“…3,4,7 These kind of registries were usually followed during the first months of the pandemic, however, data entry sometimes lapsed thereafter. That is the reason why available data on hospital admissions is focused in local or regional settings, [7][8][9] and few studies show aggregate data from a national perspective [10][11][12][13] or the pooling of data from several countries. 14 However, taking as the source of data administrative registries which are routinely fulfilled in the majority of hospitals to characterize the pandemic has been done by only a few authors.…”

Incidence of hospital admissions and severe outcomes during the first and second waves of pandemic (H1N1) 2009

“…The epidemiologic features of the hospital admissions and deaths reported in Canada are similar to those reported in many other countries in terms of demographic characteristics [8][9][10][11] and most at-risk populations, particularly with regard to underlying conditions, [8][9][10][11][12][13][14][15] pregnant women 9,16,17 and indigenous populations. 12,[17][18][19][20] The proportion of patients admitted to hospital who had severe outcomes is consistent with proportions reported in other countries (ranging from 12% to 20%).…”

Persistence of Immunogenicity of a Monovalent Influenza Virus A/H1N1 2009 Vaccine in Healthy Volunteers

“…In addition, morbid obesity elevated the possibility for comorbidities in patients hospitalized for influenza virus A H1N1 infection (4,10,18,26). Interestingly, our study showed that obese people (BMI Ն 30 kg/m 2 ) had a lower seroprotection rate than the normal weight group at week 24, although without significant difference (odds ratio: 0.61; 95% CI ϭ 0.16 to 2.32), as shown in Table 3.…”