I came across an interesing mareh makom. See Tiferes Yisroel to Avos 3:14
http://hebrewbooks.org/pdfpager.aspx?req=37946&st=&pgnum=347
where he says That Jenner (the father of modern vaccines) is one of the chasidei umos Haolam, and recieving olam haba for saving ens of thousands from death and disease