Background. The relationship between influenza virus infectivity and virus shedding, based on different diagnostic methods, has not been defined.
Methods. Three donor ferrets infected with 2009 pandemic influenza A(H1N1) underwent daily quantitative culture, antigen-detection testing, and real-time reverse transcription–polymerase chain reaction (RT-PCR). Eight contacts were sequentially cohoused with each of the donors for 24 hours during days 3–10 after inoculation.
Results. Transmission was observed until day 5 after inoculation, corresponding to high culture titers and positive results of antigen-detection tests. Real-time RT-PCR showed no relation to the cessation of transmission.
Conclusions. Antigen-detection testing and virus culture but not real-time RT-PCR identified the end of the infectious period.