The present invention relates inter alia to the treatment or prevention of influenza virus infection (including subtypes influenza A virus, influenza B virus, avian strain H5N1, A/H1N1, H3N2 and/or pandemic influenza) using compounds which inhibit the activity of p59-HCK and to a method of screening for a candidate drug substance intended to prevent or treat influenza virus infection in a subject, said method comprising identifying a test substance capable of inhibiting p59-HCK activity.