The history of three infectious diseases, smallpox, polio, and measles, – before and after a vaccine was available.
— Max Roser (@MaxCRoser) December 16, 2020
[from my @OurWorldInData post https://t.co/t2fEYgnfjg] pic.twitter.com/POQKHAsgb4
via Twitter https://twitter.com/MaxCRoser
December 16, 2020 at 02:26PM
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