A coronavirus vaccine may not arrive for at least a year—so what are the chances of finding a useful therapy that could stave off the worst effects of the virus in the meantime?

Earlier coronavirus outbreaks like SARS and MERS raised warning flags for public health officials. Fortunately, they also alerted the biological research community that this large family of viruses was worth studying in more detail. Recent research has built on a large body of knowledge about coronaviruses that have long caused significant diseases in livestock, and so SARS-CoV-2 does not arrive as a total unknown. Indeed, we are actually in a decent position to understand what might make a good potential therapy.

While some of the therapies being tested may seem random—we’re trying chloroquine, an antimalarial drug?—there’s serious biology behind what’s being done.