Last week I reported here a Stanford University study which found that infection with SARS-CoV-2 — the virus which causes COVID-19 — could be over 50 times as widespread in one Californian county than official figures suggested.

Now comes yet another piece of evidence suggesting similarly huge under-reporting of cases. Researchers from Massachusetts General Hospital performed antibody tests on 200 random members of the public they found on the streets of Chelsea, near Boston.