Scientists are studying a phenomenon called "disease tolerance." Understanding it in humans, if it exists, could revolutionize medicine. According to various estimates between 20 and 45 percent of people who get Covid-19, and possibly more – sail through the infection without realizing they had it.
South Korea's response to Covid-19 has been widely praised. The reason for their success is contact tracing. They have been able to quickly identify people exposed to the virus and the citizens comply with a 2 week quarantine to stop the spread.