Tokyo Approaches COVID-19 'Herd-Immunity'

A new, non-peer-reviewed study published on September 23, 2020, found COVID-19 infections may have spread widely across the city of Tokyo, despite the very low fatality rate. The seropositivity rate increased from 5.8% at the beginning of the study to an unexpectedly high 46.8 % by the end of the summer of 2020.

Given the temporal correlation between the rise in seropositivity and the decrease in reported COVID-19 cases that occurred without a shut-down, herd-immunity may be implicated in Japan's capital city.