NIH study reveals information on influenza virus exposure and illness
The NIH study divided 46 volunteers into five groups. Each group was exposed to various levels of the 2009 H1N1 influenza virus under extremely controlled conditions.
The virus was lab-created under Good Manufacturing Practices to replicate the 2009 H1N1 pandemic influenza. Each participant was kept in isolation at the NIH Clinical Center in Bethesda, Md., for eight days or more following exposure to the virus.
Researchers monitored the health of the participants closely throughout the study and for two months following the study. The study's objective was to find the minimum amount of exposure needed to produce nasal secretions containing the live virus in 60 percent or more of volunteers.
The researchers found that a dose of 107 TCID50 to produce a 69 percent rate of nasal secretions containing the live virus among participants; any dosage lower than this resulted in low to moderate rates of infection.
The study also gave researchers an idea of the time elapses between exposure and viral shedding, autoimmune response, onset of symptoms and duration of symptoms. Researchers hope the study can help with the development of influenza candidate vaccines for both pandemic and season influenza strains.