[flutters]

At this point lets just hope you can only get this once and not 2 to 3 times a year like a cold.

Now that is a scary thought. Has anyone caught it twice?

[I. M. Trenchant]

In the case of the devastating Spanish Flu epidemic at the end of WWI, the first wave of disease in the Spring of the year had a relatively low mortality rate, but what is believed to have been the same virus seems to have mutated, and by the autumn of the year, initiated a second wave of infection that led to the massive loss of life. So, I guess the stats are lacking, but I'd suppose that many who survived the less virulent wave in the Spring may have had limited, but improved resistance to the second infection in the autumn -- and indeed, this may have been why the mortality of the second epidemic wasn't even worse than it was.