9. April 2020, aktualisiert am 20. April 2020 – Rapid systematic review

The role of asymptomatic SARS-CoV-2 infections: rapid living systematic review and meta-analysis

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  1. What is the proportion of people that becomes infected with SARS-CoV-2 infection who do not experience symptoms at all during their infection?
  2. Amongst people who become infected with SARS-CoV-2, what proportion has no symptoms at the time of testing, but develops symptoms later?
  3. What proportion of SARS-CoV-2 infections is accounted for by people who are either asymptomatic throughout infection, or pre-symptomatic?


  1. We estimate, from empirical data, that up to 40% of people who become infected with SARS-CoV-2 will have an asymptomatic infection and will not develop symptoms during the course of their infection.
  2. Based on empirical studies, the proportion of people detected to have asymptomatic SARS-CoV-2 that goes on to develop symptoms is uncertain.
  3. Mathematical modelling studies predict that 50-60% of all SARS-CoV-2 tranmsission is the result of transmission from either asymptomatic or pre-symptomatic individuals.

Date of request: 30/3/2020
Date of response: 9/4/2020 amd 20/4/2020

In response to request from: NCS-TF Advisory Board

Comment on planned updates: This is a living systematic review. The search was updated on 20.04.2020.

Expert groups and individuals involved: Public Health

Contact persons: Prof. Nicola Low, Institute of Social and Preventive Medicine, University of Bern, Switzerland, e-mail nicola.low@ispm.unibe.ch

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