Last significant outbreak in US showed durable immunity in people vaccinated 50 years prior.
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Not to be nitpicky, but this has me a little confused. The last smallpox outbreak in the U.S. was in 1949. 8 people in the Rio Grande Valley became ill, and 1 of them died (according to an LA Times article).
Was there someone around them who didn't become ill, and who also had been vaccinated by 1899?
I'm pinging goldbux, as the question involves numbers.