To the Editor:

Our study group for infectious diseases would like to congratulate the authors of the article entitled "Pandemic influenza A (H1N1) 2009: risk factors for hospitalization"(1) for their findings.

A retrospective study was carried out at our facility between July and August of 2009, a period in which the incidence of 2009 pandemic influenza A (H1N1) virus infection was highest in the Serra Gaúcha region, located in northeastern Rio Grande do Sul, Brazil. The study consisted of a review of the cases of patients admitted to a university hospital and diagnosed with 2009 pandemic influenza A (H1N1) virus infection, as confirmed by PCR.

In that study, 64 patients with a confirmed diagnosis of influenza A (H1N1) virus infection required hospitalization. Of the 64 hospitalized patients, 90.6% were over 50 years of age; however, hospitalization was more frequently recommended for individuals under 2 years of age (34%), a finding that is inconsistent with those of the article cited above, in which most of the hospitalized patients were in the 20-29 year age bracket.(1) In addition, 6 pregnant women (9.4%), all of whom were in the third trimester of gestation, were hospitalized for influenza A (H1N1) virus infection.

The hospitalization of pregnant women with a confirmed diagnosis of influenza A (H1N1) virus infection is a topic that interests us, and, therefore, we would like to know whether there is any explanation for the fact that pregnancy was not considered a risk factor for hospitalization and whether any preventive measures were taken, given that pregnant women have been reported to constitute an at-risk population.(2,3)


Lessandra Michelim Rodriguez Nunes Vieira
Adjunct Professor of Infectious Diseases and Coordinator of the
Department of Infectious Diseases and Infection Control,
Caxias do Sul General Hospital, University of Caxias do Sul,
Caxias do Sul, Brazil

Juliano Fracasso
Infectious Disease Specialist,
Caxias do Sul General Hospital, University of Caxias do Sul,
Caxias do Sul, Brazil

Viviane Raquel Buffon
Infectious Disease Specialist,
Caxias do Sul General Hospital, University of Caxias do Sul,
Caxias do Sul, Brazil

Mariana Menegotto
Medical Student,
University of Caxias do Sul,
Caxias do Sul, Brazil

Thaiana Pezzi
Medical Student,
University of Caxias do Sul,
Caxias do Sul, Brazil

References

1. Lenzi L, Mello AM, Silva LR, Grochocki MH, Pontarolo R. Pandemic influenza A (H1N1) 2009: risk factors for hospitalization. J Bras Pneumol. 2012;38(1):57-65. PMid:22407041. http://dx.doi.org/10.1590/S1806-37132012000100009

2. Lapinsky SE. H1N1 novel influenza A in pregnant and immunocompromised patients. Crit Care Med. 2010;38(4 Suppl):e52-7. PMid:19935415. http://dx.doi.org/10.1097/CCM.0b013e3181c85d5f

3. Dodds L, McNeil SA, Fell DB, Allen VM, Coombs A, Scott J, et al. Impact of influenza exposure on rates of hospital admissions and physician visits because of respiratory illness among pregnant women. CMAJ. 2007;176(4):463-8. PMid:17296958 PMCid:1800555. http://dx.doi.org/10.1503/cmaj.061435