Thursday, January 23, 2020

Modelling China's new coronavirus

From the BBC.
"Lockdown measures are increasing across China's Hubei province to try to control the spread of a new virus that has left 17 people dead. Wuhan, Hubei's capital of 11 million people where the virus first emerged, has no trains or planes in or out. At least four other provincial cities are seeing clampdowns on transport.

"There are more than 500 confirmed cases of the virus, which has spread abroad, with Singapore, Saudi Arabia and Vietnam the latest affected."
Imagine a two-by-two matrix: one dimension is R0, the basic reproduction number; the other dimension is the survival function showing lethality. Only the square with R0 >> 1 and high lethality is a source of real concern. In that case the epidemic spreads fast and kills most of the victims.

One day we'll be able to model viruses and their mutation trees to determine whether there is an adjacent genotype to the day-zero virus which is much more dangerous. Today we have no idea - projections are just a matter of luck.

The current outbreak is rather benign so far.
"Most of the 17 victims were elderly and suffered from other chronic diseases including Parkinson's disease and diabetes."
However, there is clearly a selective advantage to any viral-mutation which more aggressively hijacks the host's body to make more virus copies - provided it doesn't kill the host too quickly. This virus currently has a long asymptomatic period, so it seems there is space for it to transition to a more lethal variant while maintaining transmission potency. We shall see.

Wash your hands - the face-masks are far from a panacea!

3 comments:

  1. I got the impression on Radio 4 at lunchtime that the value of R_0 might currently (as it mutates) be 1.5 < R_0 < 2.5 which is low by some disease standards.

    I am not sure whether to wash your hands plays much role, but if so then it should be "medically wash your hands". The main advice at the moment is: don't take Taxis in Wuhan, or public transport, or cinemas and don't partake of the Chinese New Year!

    ReplyDelete
    Replies
    1. You'll need to review this comment in two or three weeks!

      Delete
    2. Yes our knowledge might change by then. All the same this "low" R_0 value is the same as Ebola was, so it could indeed be a bumpy late winter.

      Delete

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