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The impact of sex, gender and pregnancy on 2009 H1N1 disease

Sabra L Klein12*, Catherine Passaretti3, Martha Anker4, Peju Olukoya5 and Andrew Pekosz1

Author Affiliations

1 W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA

2 Department of Biochemistry and Molecular Biology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA

3 Department of Medicine, Infectious Diseases Division, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA

4 Division of Biostatistics and Epidemiology, University of Massachusetts School of Public Health and Health Sciences, Amherst, Massachusetts, USA

5 Department of Gender, Women & Health, World Health Organization, Geneva, Switzerland

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Biology of Sex Differences 2010, 1:5  doi:10.1186/2042-6410-1-5

Published: 4 November 2010


Children and young adults of reproductive age have emerged as groups that are highly vulnerable to the current 2009 H1N1 pandemic. The sex of an individual is a fundamental factor that can influence exposure, susceptibility and immune responses to influenza. Worldwide, the incidence, disease burden, morbidity and mortality rates following exposure to the 2009 H1N1 influenza virus differ between males and females and are often age-dependent. Pregnancy and differences in the presentation of various risk factors contribute to the worse outcome of infection in women. Vaccination and antiviral treatment efficacy also vary in a sex-dependent manner. Finally, sex-specific genetic and hormonal differences may contribute to the severity of influenza and the clearance of viral infection. The contribution of sex and gender to influenza can only be determined by a greater consideration of these factors in clinical and epidemiological studies and increased research into the biological basis underlying these differences.