18 October 2020

Face-masks not only prevent Covid infections but reduce severity in those who contract virus. New UCSF analysis.

An impressive paper from Dr Monica Gandhi and colleagues* has brought together several strands of evidence showing that as well as reducing Covid-19 infections, the wearing of masks substantially reduces the severity of infections. 

Along with a persuasive hamster experiment from Hong Kong, they quote the Diamond Princess in Japan and the Greg Mortimer cruise ship in South America where symptomatic infections were 80% and 20% respectively.  This radical difference is alleged to be largely due to universal wearing of masks on the latter ship, including N95 masks for all crew members.  Several examples are quoted of large Covid clusters in factories which supplied masks with up to 95% of infections being asymptomatic.  The authors use other historical, geographical and basic science evidence to support the conclusion that the quantity of virus exposure (‘inoculum’) is related to infection severity. 

One can understand how climate change denial has a political slant but the politicisation of mask wearing seems beyond explanation.  Older readers may remember a minority who refused to use seat belts when they were introduced.  They were soon silenced by statistics showing reduced injuries and saved lives.  Masks were widely used in the 1918 influenza epidemic – and made compulsory in many jurisdictions.  Yet there were ‘conscientious objectors’ then as now. 

We should all wear masks when in buses, trains, elevators, taxis, shops, etc, as currently advised by many health authorities. 

Written by Andrew Byrne, Redfern Addictions Physician.  Usual email ajbyrne@ozemail.com.au


* Gandhi M, Beyrer C, Goosby E. Masks Do More Than Protect Others During COVID-19: Reducing the Inoculum of SARS-CoV-2 to Protect the Wearer. 2020 Journal of General Internal Medicine.   


One More Reason to Wear a Mask: You’ll Get Less Sick From COVID-19. News Summary from UCSF.                    



Chronology of COVID-19 Cases on the Diamond Princess Cruise Ship and Ethical Considerations: A Report From Japan.


COVID-19: in the footsteps of Ernest Shackleton.


Surgical Mask Partition Reduces the Risk of Noncontact Transmission in a Golden Syrian Hamster Model for Coronavirus Disease 2019 (COVID-19)