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Contagious period for pandemic (H1N1) 2009
Gaston De Serres1, Isabelle Rouleau, Marie Eve Hamelin
1Institut National de Sante Publique du Quebec, Quebec City, Quebec, Canada.
Emerging Infectious Diseases
|April 23, 2010
Summary
Most people with pandemic H1N1 (swine flu) shed infectious virus for longer than previously thought. Current self-isolation guidelines may not be sufficient to prevent transmission of this flu virus.
Area of Science:
- Virology
- Infectious Diseases
- Epidemiology
Background:
- Pandemic (H1N1) 2009 virus, commonly known as swine flu, caused a global outbreak.
- Understanding viral shedding duration is crucial for effective public health interventions.
Purpose of the Study:
- To determine the proportion of individuals shedding infectious pandemic (H1N1) 2009 virus at diagnosis and on day 8 of illness.
- To assess the effectiveness of current self-isolation recommendations.
Main Methods:
- Nasopharyngeal swabs were collected from household members with confirmed pandemic (H1N1) 2009 cases.
- Samples were tested using Polymerase Chain Reaction (PCR) and virus culture.
- Viral shedding was assessed at diagnosis and on day 8 of illness.
Main Results:
- At diagnosis, 92% of febrile and 63% of afebrile individuals shed infectious virus.
- On day 8, 74% remained PCR positive, and 19% were still culture positive for infectious virus.
- A minimum of 8% of presumed cases shed replicating virus on day 8.
Conclusions:
- Self-isolation solely until fever subsides is insufficient to prevent pandemic (H1N1) 2009 transmission.
- A longer isolation period, such as one week, may be more effective, though some individuals may still shed infectious virus.
- Revised public health guidance on isolation duration is warranted.
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