It’s been a steep learning curve. SARS-CoV-2, the virus that causes COVID-19, is a monster. It’s not like influenza. It’s not like the other common-cold coronaviruses. Figuring out how it infects and how it kills has been an enormous challenge. We’ve learned a lot, but there’s a long way yet to go.
At the beginning of the pandemic, health officials assumed the virus spread by droplets and close contact. An infected person…