Simplified thread on how public messaging has effectively utilized the ambiguity of the basic reproduction number (R0) to claim that #COVID is currently in an endemic status.
Q 1 :What is R0?
Q2: How is it related to an infectious disease being classified in endemic status?
Q2: How is it related to an infectious disease being classified in endemic status?
Deriving this epidemiological metirc hinges on an advanced modern mathematical framework, but I will bypass the deep theory in an effort to make it more digestible.
To guide this discussion, it is pertinent to refer to the original epidemic model proposed by W. O. Kermack and A. G. McKendrick in 1927. See the figure below. 
This figure is a schematic diagram of a SIR model consisted of three compartments, namely: susceptible (S), infected (I) and recovered (R). Humans progress through each compartment subject to the rates described above. The corresponding dynamical system is listed below.
The basic reproduction number is the average number of sec- ondary infections generated by a single infection in a completely susceptible population. It is proportional to the product of infection/contact (a), contact/time (b) and time/infection (c).
The quantity a is the infection probability between susceptible and infectious individuals, b is the mean contact rate between susceptible and infectious individuals and c is the mean duration of the infectious period.
The case of an increasing infected sub-population corresponds to the occurrence of an epidemic. This happens provided that
Under the assumption that in the beginning of an epidemic, virtually the total population is, that is
As a result, we arrive at the following equivalent condition
The parameter β in the Figure is equal to ab and ω is equal to c^−1. This combination of parameters stands to reason as it is a ratio of the effective contact rate β and the mean infectious period ω^−1.
The main issue: This quantity is often not the actual average amount of secondary infections (which would be utilized to determine endemic status).
It's a mathematical threshold which quantifies the local asymptotic stability of the underlying dynamical system. See the diagram.
It's a mathematical threshold which quantifies the local asymptotic stability of the underlying dynamical system. See the diagram.
As a result, it is is extremly susceptible to #misinformation. Public messaging is comparing apples and oranges.
This is the game that is being played.
Use "right" model, manipulate the data and Voila! you can claim endemic status.
This is the game that is being played.
Use "right" model, manipulate the data and Voila! you can claim endemic status.
Infectious diseases in endemic equilibrium have a precise mathematical meaning. The effective (time dependent R0 is stably near 1).
This is not what is happening on the ground and this is the method they are using to market #COVID as an endemic.
This is not what is happening on the ground and this is the method they are using to market #COVID as an endemic.
From the beginning I said it now It’s become reality…we living in a #multiyearpandemic
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