Coronaviruses aren't new. For more than 20 years, German virologist Rolf Hilgenfeld has been looking for ways to slow or stop the virus. What does it take to find a treatment for coronaviruses, and what might that mean for the future of COVID-19? For more information on this episode, visit nationalgeographic.com/overheard Want more? Rolf Hilgenfeld is one of the many people who are trying to test and develop medicine for COVID-19. Nat Geo reporter Michael Greshko has put together an article explaining the other approaches out there. On our Coronavirus Coverage page you can find National Geographic's most up-to-date articles on the pandemic, including news and explanations of the science. On that page, other articles provide new perspectives, such as how astronauts handle social isolation, and what people used to do before toilet paper was invented. And if you've had too much news about the pandemic, Nat Geo has put together a new newsletter called Escape, full of awe-inspiring pictures, compelling stories, and no COVID-19 updates whatsoever. Also explore: If you'd like to dive deeper into the antiviral compound Rolf Hilgenfeld has been developing, check out the research paper. The CDC website is the best source for new information about COVID-19 and how you can stay safe and keep others around you safe. If you like what you hear and want to support more content like this, please consider a National Geographic subscription. Go to natgeo.com/exploremore to subscribe today.  Learn more about your ad choices. Visit podcastchoices.com/adchoices