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Correspondence |

First Influenza Season Outbreak After 2009 Pandemic Influenza A(H1N1) in SpainAn(H1N1) Virus, Viral Pneumonia FREE TO VIEW

Alejandro Rodríguez, MD,PhD; Francisco Pozo, MD,PhD; Cristóbal León, MD
Author and Funding Information

From the Critical Care Department (Dr Rodríguez), Hospital Universitario Joan XXIII, IISPV (Institut d’Investigaciò Sanitaria Pere Virgili)/URV (Universitat Rovira i Virgili)/CIBER (Centros de Investigación Biomédica en Red) Enfermedades Respiratorias; the Pulmonology Department (Dr Pozo), Hospital Universitario 12 de Octubre/CIBER Enfermedades Respiratorias; and the Critical Care Department (Dr León), Hospital Universitario de Valme/CIBER Enfermedades Respiratorias.

Correspondence to: Alejandro Rodríguez, MD, PhD, Joan XXIII University Hospital, Critical Care Department, Av. Paisos Catalans 15B 1-1, Tarragona, Spain 43007; e-mail: ahr1161@yahoo.es


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).


© 2011 American College of Chest Physicians


Chest. 2011;140(4):1102-1103. doi:10.1378/chest.11-1167
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To the Editor:

Several reports have been written about the pandemic 2009 influenza A(H1N1) (A[H1N1]). However, little information is available on the emergence of the later strain, new virus A(H1N1) (An[H1N1]) in the winter of 2010 to 2011.1 Unexpectedly, during the European winter of that period the usual seasonal viruses were replaced by the An(H1N1) virus, and in Spain, 447 patients with severe infection were admitted to the ICU. Although the presenting features of An(H1N1) influenza were quite similar to those described for patients in the ICU with A(H1N1),2-4 some differences should be pointed out. The patients with An(H1N1) were somewhat older (49.7 ± 14.3 years vs 44.7 ± 14.9 years); similarly, the frequency of increased disease severity (APACHE [Acute Physiology and Chronic Health Evaluation] II score 16.4 ± 7.4 vs 13.9 ± 7.2) and multiorgan dysfunction (Sequential Organ Failure Assessment score 6.3 ± 3.8 vs 5.5 ± 3.5) were higher (P < .001) in patients with An(H1N1) than those observed previously in patients with A(H1N1).5 The frequency of comorbidities was similar in both periods, but there was an increase in the number of patients with hematologic disease (11.1% vs 5.3%, P < .001) and HIV infection (4.1% vs 2.1%, P = .03).1,4 Viral pneumonia was the leading cause of hospitalization in both periods. However, a small but significant increase in the need for invasive mechanical ventilation in patients during the seasonal outbreak (69% vs 61.5%, P < .01) was observed.5 The implementation of early (< 2 days) antiviral therapy was associated with a better survival rate.5 Although all patients received antiviral treatment, in the seasonal outbreak, a 1-day delay (5 days instead of 4 days) in the antiviral administration was observed. This apparent treatment delay could be associated with a corresponding difference in the time from symptoms onset to hospital (4.9 days vs 4.3 days, P < .01) or ICU admission (2.3 days vs 1.8 days, P < .01).5 All of these variables must be considered to explain the higher mortality rate observed in patients undergoing invasive mechanical ventilation during the seasonal outbreak of An(H1N1) (42.6%) compared with patients with A(H1N1) (34.2%, P < .001).5 APACHE II score (OR = 1.1; 95% CI, 1.06-1.12), invasive mechanical ventilation (OR = 8.3; 95% CI, 4.32-15.91), hematologic disease (OR = 3.0; 95% CI, 1.66-5.49), HIV infection (OR = 3.9; 95% CI, 1.38-11.51), and antiviral therapy (OR = 0.45; 95% CI, 0.28-0.73) were variables independently associated with mortality. Finally, only 6.2% of patients admitted to the ICU during the seasonal outbreak were vaccinated, and they seemed to have a more favorable outcome with shorter ICU stay (3 days) and fewer days under invasive mechanical ventilation (3 days).

Seasonal flu during the winter of 2010 to 2011 was dominated by the An(H1N1) virus and survival of intubated patients was < 60%. Delay in diagnosis, a low rate of vaccination, and suboptimal antiviral therapy indicate the need to improve educational measures and public information management for the coming years.

Rodriguez A, Martín-Loeches I, Bonastre J, et al. First influenza season after the 2009 pandemic influenza: report of the first 300 ICU admissions in Spain. Med Intensiva. 2011;35:208-216 [CrossRef] [PubMed]
 
Martin-Loeches I, Rodriguez A, Bonastre J, et al; H1N1 SEMICYUC Working Group H1N1 SEMICYUC Working Group Severe pandemic (H1N1)v influenza A infection: report on the first deaths in Spain. Respirology. 2011;161:78-85 [CrossRef] [PubMed]
 
Martín-Loeches I, Sánchez-Corral A, Díaz E, et al. H1N1 SEMICYUC Working Group. Community-acquired respiratory co-infection (CARC) in critically ill patients infected with pandemic 2009 influenza A(H1N1) virus infection. Chest. 2011;1393:555-562 [CrossRef] [PubMed]
 
Díaz E, Rodríguez A, Martin-Loeches I, et al; H1N1 SEMICYUC Working Group H1N1 SEMICYUC Working Group Impact of obesity in patients infected with 2009 influenza A(H1N1). Chest. 2011;1392:382-386 [CrossRef] [PubMed]
 
Rodríguez A, Díaz E, Martín-Loeches I, et al. Impact of early oseltamivir treatment on outcome in critically ill patients with 2009 pandemic influenza A. J Antimicrob Chemother. 2011;665:1140-1149 [CrossRef] [PubMed]
 

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Rodriguez A, Martín-Loeches I, Bonastre J, et al. First influenza season after the 2009 pandemic influenza: report of the first 300 ICU admissions in Spain. Med Intensiva. 2011;35:208-216 [CrossRef] [PubMed]
 
Martin-Loeches I, Rodriguez A, Bonastre J, et al; H1N1 SEMICYUC Working Group H1N1 SEMICYUC Working Group Severe pandemic (H1N1)v influenza A infection: report on the first deaths in Spain. Respirology. 2011;161:78-85 [CrossRef] [PubMed]
 
Martín-Loeches I, Sánchez-Corral A, Díaz E, et al. H1N1 SEMICYUC Working Group. Community-acquired respiratory co-infection (CARC) in critically ill patients infected with pandemic 2009 influenza A(H1N1) virus infection. Chest. 2011;1393:555-562 [CrossRef] [PubMed]
 
Díaz E, Rodríguez A, Martin-Loeches I, et al; H1N1 SEMICYUC Working Group H1N1 SEMICYUC Working Group Impact of obesity in patients infected with 2009 influenza A(H1N1). Chest. 2011;1392:382-386 [CrossRef] [PubMed]
 
Rodríguez A, Díaz E, Martín-Loeches I, et al. Impact of early oseltamivir treatment on outcome in critically ill patients with 2009 pandemic influenza A. J Antimicrob Chemother. 2011;665:1140-1149 [CrossRef] [PubMed]
 
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