Prevalence of infection with the drug sensitive virus (solid lines in black), the drug resistant one (dashed lines) and the sum of both (dotted lines). All cases who seek medical help ('outpatients') receive antiviral treatment. The grey curves indicate the fractions of resistant infections among all infections. In all 3 graphs, resistance develops de novo in 4.1% of children and 0.32% of adults who receive treatment. (a) Drug-sensitive infections are imported on day 0 and 21; (b) Drug sensitive infection is imported on day 0, followed by a drug-resistant one on day 21; (c) Drug resistant infection is imported on day 0, followed by a drug-sensitive one on day 21. Further assumptions: (1) Swiss population of 100,000 individuals. (2) R0 = 2.5 for the drug sensitive and the drug resistant virus. Both strains are assumed to have the same transmissibility. (3) One third of all infected individuals become severely sick and seek medical help. Antiviral treatment reduces their contagiousness by 80% and their duration of sickness by 25% if they are infected with the drug sensitive virus. (4) General social distancing reduces the number of contacts by 10% for all individuals; isolation additionally prevents 10%, 20% and 30% of contacts of moderately sick cases, severely sick cases at home, and hospitalized cases, respectively. For references about assumptions and parameter values see text.