Secondary Infections Were a Major Cause of Death During 1918 Flu Pandemic, Research Finds

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ScienceDaily (Nov. 2, 2010) ? Secondary infections with bacteria such as Streptococcus pneumoniae, which causes pneumonia, were a major cause of death during the 1918 flu pandemic and may be important in modern pandemics as well, according to a new article in the Journal of Infectious Diseases co-authored by David M. Morens, M.D., senior advisor to the director of the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.

The researchers examined 13 studies published between 1918 and 1920. During this time, many scientists erroneously believed that influenza was caused by bacteria, not a virus. As a result, researchers began performing and publishing results from clinical trials testing bacterial vaccines designed to prevent the flu.

In their new study, Dr. Morens and his colleagues used modern statistical and evaluation methods to re-analyze the vaccine effectiveness data from these old studies in an attempt to correct for any statistical biases in the original analysis.

In addition to confirming the importance of bacterial infections associated with the 1918 influenza pandemic, the new analysis suggests that the use of bacterial vaccines containing S. pneumoniae could reduce pneumonia rates and deaths in modern influenza pandemics as well. During the 2009-2010 H1N1 influenza pandemic, the authors write, autopsy results implicated bacterial infections in 29 to 55 percent of deaths.

In light of this study, the authors recommend more research into the use of bacterial vaccines to prevent illness and death associated with influenza.

http://www.sciencedaily.com/release...encedaily (ScienceDaily: Latest Science News)

 

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Re: Secondary Infections Were a Major Cause of Death During 1918 Flu Pandemic, Research Finds

The Journal of Infectious Diseases 2010;202:1639?1648
? 2010 by the Infectious Diseases Society of America. All rights reserved.
0022-1899/2010/20211-0005$15.00
DOI: 10.1086/657144
MAJOR ARTICLE
Efficacy of Whole‐Cell Killed Bacterial Vaccines in Preventing Pneumonia and Death during the 1918 Influenza Pandemic

Yu‐Wen Chien,1

Keith P. Klugman,1 and

David M. Morens2

1Rollins School of Public Health, Emory University, Atlanta, Georgia; 2National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland

Background.Most deaths in the 1918 influenza pandemic were caused by secondary bacterial pneumonia.

Methods.We performed a systematic review and reanalysis of studies of bacterial vaccine efficacy (VE) in preventing pneumonia and mortality among patients with influenza during the 1918 pandemic.

Results.A meta‐analysis of 6 civilian studies of mixed killed bacterial vaccines containing pneumococci identified significant heterogeneity among studies and estimated VE at 34% (95% confidence interval [CI], 19%?47%) in preventing pneumonia and 42% (95% CI, 18%?59%) in reducing case fatality rates among patients with influenza, using random‐effects models. Using fixed‐effect models, the pooled VE from 3 military studies was 59% (95% CI, 43%?70%) for pneumonia and 70% (95% CI, 50%?82%) for case fatality. Military studies showed less heterogeneity and may provide more accurate results than civilian studies, given the potential biases in the included studies. Findings of 1 military study using hemolytic streptococci also suggested that there was significant protection.

Conclusions.Despite significant methodological problems, the systematic biases in these studies do not exclude the possibilities that whole‐cell inactivated pneumococcal vaccines may confer cross‐protection to multiple pneumococcal serotypes and that bacterial vaccines may play a role in preventing influenza‐associated pneumonia.

http://www.journals.uchicago.edu/doi/abs/10.1086/657144