Covid-2019 - 2022-05-27

Interesting lesson in epidemiology from China's experience. Until the last several months, it had the highest case-fatality ratio in the world, between 4% and 5%. That's because the first wave of the virus in early 2020 was especially lethal before we knew how to treat it. Then there was more than a year with almost no new cases (at least not reported), so the ratio remained in place. Then China's 2022 case-wave came, associated with very few deaths (at least as reported). So China's case-fatality ratio has fallen from worst in the world to best, at 0.43%. A dropping ratio is typical in epidemiology -- but no place shows it more starkly and suddenly than China.