Illustration of an influenza (flu) B virus neuraminidase complexed with the antiviral drug oseltamivir. The presence of neuraminidase on the virus surface enables the virus to be released from the host cell. Oseltamivir (marketed as Tamiflu) binds to neuraminidase, inhibiting it and so preventing the virus from being able to infect other cells. It can be taken to prevent infection, or to reduce the symptoms and the duration of the infection.