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Covid-19: four fifths of cases are asymptomatic, China figures indicate

BMJ 2020; 369 doi: https://doi.org/10.1136/bmj.m1375 (Published 02 April 2020) Cite this as: BMJ 2020;369:m1375

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  1. Michael Day
  1. London

New evidence has emerged from China indicating that the large majority of coronavirus infections do not result in symptoms.

Chinese authorities began publishing daily figures on 1 April on the number of new coronavirus cases that are asymptomatic, with the first day’s figures suggesting that around four in five coronavirus infections caused no illness. Many experts believe that unnoticed, asymptomatic cases of coronavirus infection could be an important source of contagion.

A total of 130 of 166 new infections (78%) identified in the 24 hours to the afternoon of Wednesday 1 April were asymptomatic, said China’s National Health Commission. And most of the 36 cases in which patients showed symptoms involved arrivals from overseas, down from 48 the previous day, the commission said.

China is rigorously testing arrivals from overseas for fear of importing a …

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