https://www.wired.com/story/frontrunners-emerge-in-the-race-for-a-covid-19-vaccine/

It’s been four months since researchers in China sequenced the novel coronavirus now known as SARS-CoV-2. In those four months, at least 3.8 million people around the world have been diagnosed with Covid-19, the deadly respiratory disease it causes. As of Friday morning, more than 267,000 people have died. Doctors have been trying lots of existing drugs—from malaria medications to anti-influenza pills to Ebola treatments—in an effort to save patients from the ravages of the disease, which can damage the heart, kidneys, brain, and lungs. But so far, no blockbusters have emerged. Researchers are still testing hundreds of potential candidates in search of a cure.

A vaccine, which would teach people’s immune systems to recognize and fend off the virus before an infection can take hold, would be even better. An inoculated public could get back to work, stop sheltering in place, resume normal life. Developing a safe, effective vaccine against a new pathogen typically takes years, if not decades. That’s because, unlike with experimental treatments, it’s impossible to know right away if a vaccine has worked. During testing, researchers have to wait for participants to encounter the real virus in the wild, which if people are sheltering in place or an outbreak has ended, can take a very long time.