Principales características de la pandemia por el nuevo virus influenza A (H1N1)

An estimate of the incidence of influenza-like illness during the influenza pandemic of 2009

INTRODUCTION

The influenza pandemic of 2009 had a great social impact. Many health resources were devoted to the care, prevention and surveillance of this disease. Epidemiological surveillance is based on the reporting of cases of influenza-like illness (ILI) and confirmed influenza cases. The objective was to estimate the true incidence of ILI during the influenza pandemic of 2009.

METHODS

The capture-recapture method was applied during the month of highest influenza incidence in Castellón. Two notification systems were used: (i)electronic reporting of Notifiable Diseases (ND), and (ii)laboratory-based (LAB) data collection. Estimates were made by stratifying by age group and week. Independence coefficients were calculated for those strata.

RESULTS

No dependence was found between stratification variables and the reporting system. A total of 7,181 ND cases and 524 LAB cases were identified, of which 211 were recorded in both systems. The estimated total of cases was 17,785 in a single month. In the study period, almost 4% of people in the area suffered flu symptoms (cumulative incidence), with 1% being affected each day (daily prevalence). The sensitivity of the ND system was 40%, i.e., the percentage of patients seeking primary care.

CONCLUSIONS

To obtain an estimate of the actual incidence of influenza-like illness in the population during a pandemic period, the number of medical consultations should be multiplied by a factor of 2.5. This factor is lower than that estimated for periods without pandemic alert.

Relação entre morbidade hospitalar e cobertura vacinal contra Influenza A

OBJETIVO: Analisar o perfil dos indivíduos acometidos pelo vírus Influenza A (H1N1), e o impacto vacinal nos grupos prioritários à vacinação. MÉTODOS: Estudo ecológico, observacional, de caráter retrospectivo, com população de indivíduos residentes na cidade de Maringá-PR e submetidos à internação por Influenza A entre 2009 e 2010. RESULTADOS: No ano de 2009, ocorreram 614 internações decorrentes de infecção pelo vírus Influenza A em Maringá-PR. A disponibilização da vacina fez com que o número de acometidos diminuísse para 169 em 2010, ocorrendo impacto vacinal nos seguintes grupos populacionais: gestantes, portadores de doenças crônicas e adultos de 20 a 39 anos. CONCLUSÃO: Identificou-se a necessidade de estender a faixa etária de vacinação para crianças de 2 a 4 anos e preenchimento dos impressos de vacinação dos indivíduos e grupos vacinados com maior rigor.

[Patient characteristics and health care burden during the influenza A (H1N1) 2009 pandemic in the university Hospital Vall d'Hebron of Barcelona]

BACKGROUND AND OBJECTIVE

The influenza A (H1N1) 2009 pandemic initially had a mild impact in Catalonian hospitals, but in the autumn there was an important pandemic wave. We describe the main characteristics of patients seen in the Vall d'Hebron University Hospital in Barcelona (HUVH) during this pandemic, the risk factors associated with hospitalization and the health-care burden generated.

MATERIAL AND METHOD

We included all cases of influenza A (H1N1) 2009 with laboratory confirmation seen in the HUVH from July 2, 2009 to January 22, 2010. We performed a descriptive analysis of the cases and a multivariate analysis to identify variables associated with the risk of hospitalization.

RESULTS

The diagnosis was confirmed in 741 patients; 56.8% were under 16 years, while only 2.8% were 65 and over. Thirty three per cent of children had no risk factor for complications, whereas in adults it was 45%. One hundred and ninety cases were hospitalized, 26 of them in the intensive care unit (ICU) with 5 deaths. The factors associated with risk of hospitalization were, age less than one year, immunodeficiency, and neuromuscular disease in children; and chronic lung disease in adults. The diagnosis of pneumonia in the emergency department was an important predictor of hospitalization in both children and adults. The maximum caseload was recorded on November 19, with 43 hospital admissions, 6 of them in the ICU.

CONCLUSIONS

Between July and September 2009 the pandemic had a low impact on hospital resources, but in autumn there was a marked increase in emergency department visits and hospitalizations. Children had higher rates of confirmed cases, while adults had higher rates of hospitalizations. The risk of hospitalization was higher in patients with certain conditions especially in those with pneumonia. The pandemic wave was a moderate work load for HUVH, since it did not involve any modification of the usual health care programs.