I mean, anything is possible. Death rays from mars could strike me down tomorrow at 10 am. But it is certainly unlikely that a given antiviral would be effect

I mean, anything is possible. Death rays from mars could strike me down tomorrow at 10 am. But it is certainly unlikely that a given antiviral would be effective for long. Tamiflu is very much widely available, but it is not really deployed (administered) at scale. At peak, and now down >50%, tamiflu sales were about 1B. Even if tamiflu were $1 a dose (it's not), we are talking about a very very small portion of the global influenza patients having taken it. So yes I think that, if tamiflu were a strong protection against severe flu (it's not) and it were deployed at scale (never has never was), its usefulness would not last long.