Sir, We were moved to respond to the recent letter on the nature of airborne spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) [ 1 ]. There is currently intense debate over how much transmission occurs through the production of aerosols <5 μm, which have the capacity to remain airborne for hours and are thus at the mercy of prevailing draughts or ventilation currents [2]. If SARS-CoV-2 is emitted in aerosol in this manner, then susceptible persons may inhale the virus outside the statutory 1–2 m distance imposed by infection prevention bodies and the World Health Organization ( It is important to better ascertain the risk of aerosol spread before ruling it out completely. Should the main mode of transmission be due to droplets (>5 μm) and direct contact, as currently advocated, then advice on preventive measures would be adequate. But evidence is beginning to accumulate that implies a more important role for aerosol spread and this demands an urgent reassessment of respiratory precautions [2].


Eneas De Troya from Mexico City, México [CC BY 2.0 (], via Wikimedia Commons

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