It was not any one of the several flus going around. Cases are being extensively tracked, and negatives from tests in at least some states are more than ten to one as compared to positives. No great percentage of the population has been exposed.
A small sample space but interesting. I honestly wonder if it extrapolates to larger populations.
Clearly, it has been around long enough to achieve this kind of stat.
Wonder if Washington State and California exposure rates and people with antibodies will be higher.