COVID-19

If a new BBC Persian report is accurate, the death toll from coronavirus in Iran is far higher than the official numbers.
"When the facts change, I change my mind. What do you do, sir?"
As the Wuhan coronavirus (COVID-19) epidemic continues to spread -- and, at this point, it doesn't look to be stopping anytime soon -- pharmaceutical companies and governments are working together to make vaccines against it.
Before modern study of microbiology, how diseases spread was essentially unknown.