It was informative still- I was surprised that the average lifespan was only 45. It does make some sense I suppose: penicillin was still thirty years away and there wasn't a single vaccine yet.
The vaccine had been invented more than 100 years prior to 1900. I'm not sure how wide-spread they were at that point, but the vaccine was invented some time in the 18th century. Antibiotics -- you're right, not discovered yet in 1900.
I stand corrected. Wikipedia lists some interesting proto-vaccines in the 1800s and earlier (including one for smallpox). There was a major increase in the availability and breadth of vaccines in the 1900s, but a lot of groundwork was already laid before that. Thanks for the correction.