Actual infections 5x the number of cases detected through testing in rich, developed countries with relatively widespread tests seems pretty plausible, I think

Actual infections 5x the number of cases detected through testing in rich, developed countries with relatively widespread tests seems pretty plausible, I think there's some evidence the UK was close to that despite testing pretty heavily compared to the rest of the world e.g. https://www.news-medical.net/news/20210215/Only-2525-of-SARS-CoV-2-infections-are-detected-in-the-UK-Study.aspx https://www.news-medical.net/news/20210215/Only-2525-of-SARS... (I seem to recall the BBC reported on this at the time, but finding their old Covid-19 coverage again is basically impossible.) Remember, fully asymptomatic infections aren't the only problem, there are also infections that technically have symptoms but they're too vague, commonplace and non-specific to lead to people getting tested.