1/ The Nobel laureate André Lwoff suggested part of the hypothesis in 1959, when he noted that the degree of virulence of viruses is often related to their level of thermal sensitivity
2/ In 1979, Richman and Murphy developed this further, discussing many examples of thermal sensitivity in natural and lab‐made viral strains, and noting that the near‐universal attenuation of ts strains made them good candidates for vaccines. doi.org/10.1093/clinid…
3/ The full hypothesis was proposed by Shaw Stewart and discussed at length in 2016, focusing on seasonality and the natural selection of strains with varying degrees of thermal sensitivity and pathogenicity
7/7 A lot of scientists seem to struggle with this idea - though @JuliaLBach8 and I think we are pretty much stating the obvious - well-understood by folk wisdom for generations !
My friend Brian (non-scientist) gets it
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IMO you can’t understand CoV-2 or any other virus without understanding the "virulence-transmission trade-off hypothesis"
This hypothesis was introduced in the 1950s to explain observations of myxomatosis. Basically, very mild strains became moderate, while very virulent ones also became moderate
The hypothesis says a virus must balance the amount of shedding against the time during which the shedding takes place – the time will be reduced if viral virulence is too great
The UK 10-day self-isolation period is highly disruptive to industry.
But it may also be counter-productive in combating Covid-19.
2/ 5
We know that Covid-19 incubation periods vary hugely, with some illnesses appearing 2 or 3 days after exposure, but others taking 14 days or more.
Some of this variation is likely to be related to the properties of the particular “isolate” (ie strain) involved.
3/ 5
It is also likely that strains with short incubation periods are more pathogenic. This is the basis of the “virulence-transmission trade-off hypothesis” and has been proposed for several viruses including influenza and myxomatosis.