You're most welcome. It was a case of "killer flu" in 1983 during which I could keep no foods or liquids down, that drained me of strength, like you say, for a month or more. It convinced me to get the flu shot each year when it is available. I haven't had a severe case of flu since.
We lived in a small Texas town near the coast from '63 to '79. In the winter the entire town had the flu and we had it every year. Some years maybe one person (in our family) would escape it but some years one person might have several strains. That is when I became very well acquainted with the flu. In '79 we moved to Houston and we haven't had the flu since, and also we started getting yearly flu shots some time after we moved.