Sunday, 10 May 2020

What are the main methods of coronavirus transmission?

LETTER TO SCMP:
I was shaken to see a senior official at a WHO press briefing unable to answer a simple question: what is the main method of the novel coronavirus transmission? 
Dr Maria Van Kerkhove couldn’t say (18’) which of the three main methods is primary: (1) large respiratory droplets (2) tiny aerosols (3) contaminated surfaces (fomites).
In effect, she said “We don’t have the data”.
But why not? The key mission of the WHO is prevention and control  of infectious diseases. Knowing the specific method of virus transmission has huge implications for how it is spread and how to control it. 
We are all concerned these days with the coronavirus “R” number and the need to keep it below one. “R” is an average and it appears that the spread of coronavirus is subject to the 80/20 principle: 80% of the spread is by 20% of people. They have a disproportionate effect on R. 
This occurs in Super Spreader Events (SSE). A recent analysis of public data in 28 countries by Jonathan Kay suggests the main transmission method is by Large Respiratory Droplets (aka “ Fl├╝gge droplets”). 
If confirmed, this has important implications for how to control the virus as we emerge from lockdowns. It means, for example, that cinemas, theatres and opera houses will generally be safe places to go, and importantly flying will generally be safe, whereas public gatherings such as football matches are less so, and will require masking. (The reasons are explained in the Kay article).
I have a suggestion. If the WHO can’t be bothered doing this basic research, how about our own government? Follow up and expand on the preliminary analysis done by Mr Kay — which he readily admits is less than comprehensive. Have it peer-reviewed and make the results public. 
A clearer understanding of specific spreading methods in SSEs would be a major contribution to world health and economic revival. And a fitting epitaph to the success Hong Kong has had in controlling the coronavirus, a success largely unrecognised to date.

Pf, etc…