Surveillance of influenza A H1N1 2009 among school children during 2009 and 2010 in São Paulo, Brazil

Abstract

Introduction: Influenza A H1N1 2009 is associated with a high morbidity rate among children around the world, including Brazil. This survey was conducted on samples of symptomatic children (≤ 12 years) to investigate the influenza virus as the etiological agent of respiratory infections in a day care school in a health facility during the first and second pandemic wave of H1N1 (2009)(2010) in São Paulo, Brazil. Methods: Influenza infections were determined by real-time PCR in 34% (47/137) of children with a median age of 5 years (8 months -12 years), from June to October 2009 and in 16% (14/85) of those with median age of 6 years (1-12 years), from March to November 2010. Results: In general, most positive cases (64%) occurred in children aged 5-12 years, this age group was significantly the most affected (39.8%, p = 0.001, OR = 8.3, CI 95% 1.9-36.9). Wheezing was reported by 31% (19/61) and dyspnea by 23% (14/61) of the studied patients. An outbreak of influenza H1N1 with an attack rate of 35.7% among children (median age 6 years) was documented in April 2010, before the vaccination campaign against the pandemic virus was extended for children up to 5 years in Brazil. Conclusions: Therefore, the study reinforces the recommendation to immunize school children to reduce the incidence of the disease.

A Descriptive Study of Pandemic Influenza A(h1n1)pdm09 in Brazil, 2009 - 2010

“…As a result of our study, among the total of reported cases, the highest frequency occurred in females, children and young adults who are white, with an educational level of completed high school and residents in urban areas were the most frequently notified, as well as confirmed cases of influenza A(H1N1)pdm09 were found. Such findings are supported by results of other authors 20,21,[23][24][25][26][27][28] .…”

Analysis of respiratory virus prevalence in assisted children in a university hospital of southern of minas gerais

“…Of the 159 hospital patients, the infection with influenza A (H1N1) was confirmed in 31 (19.5%). 11 Guatura et al 14 also observed the influenza A (H1N1) as the most prevalent in their study. The symptoms simulating a flu syndrome mild to severe pneumonia and death, and the first wave of the outbreak of A (H1N1) led to a large number of hospitalizations for suspected infection also that year.…”

Comparative study of lymphocytes from individuals that were vaccinated and unvaccinated against the pandemic 2009-2011 H1N1 influenza virus in Southern Brazil

“…Indeed, in a study of Brazilian school children, frequent exposure to seasonal infl uenza virus strains was not a relevant factor for preventing infection by swH1N1 in 2010 (14) . These fi ndings demonstrate that the relationship between previous exposures to closely related strains of the infl uenza virus and protection during an epidemic is not applicable to all situations.…”