Some people question why the current coronavirus has brought the world to standstill while a previous deadly coronavirus, SARS, did not.
Others have questioned why a vaccine is so urgently needed now to stop the spread of the current coronavirus when a vaccine was never developed for SARS.
I study viruses and am so fascinated by their complexity that I have written a book about them. The tale of SARS and its new cousin that causes COVID-19, SARS-CoV-2, shows just how unpredictable viruses can be, particularly when they jump from animals to humans. Understanding emerging, infectious diseases needs to be a priority. SARS, which killed about one in 10 infected people, turned out to be highly lethal but ultimately, and somewhat mysteriously, disappeared.