Twenty-six patients in a University of Costa Rica clinical trial are due to receive an experimental serum of coronavirus antibodies derived from horses, Reuters reports. The researchers injected the virus that causes COVID-19 into six horses, then collected antibodies from their blood and plasma a few weeks later to create a treatment that, if it works, would be relatively inexpensive to produce on a larger scale. The method is similar to the process Costa Rican scientists use to create anti-venom for snakebites, which is where researchers got the idea. In the U.S., some coronavirus patients are given antibody-rich plasma from humans who have contracted and recovered from COVID-19.