# COVID-19 / SARS-COVID-2

### Effectiveness of Response to COVID-19: Comparisons Between Regions

Daily number of infected people
The "response" metric (in days) gives the "lost time" in coping with COVID-19.
(Most recent data may be incomplete.)

World-Wide Best Response

World-Wide Worse Response

Reproduction Number R(t)
Equation: R(t) nc(t) = ni(t) using the delays: ni(t) = nc(t + 5 days) = nr(t + 12 days).
R(t) nr(t + 7 days) = nr(t + 12 days), where ni(t), nc(t) and nr(t) are
the infected, contagious and reported daily-number of people, respectively.

For Ottawa: infection R>1 after Stage-2 reopening on June 12th.

Regions' Response: from Best to Worse
Minimum 100 reported cases and 10 deaths.
The "response" metric (in days) gives the "lost time" in coping with COVID-19.

Currently hospitalized in Ottawa.
Green curve shows a 7-day average delayed by 3 days.

Scale-free Network as a Model of Propagation.
Power law model P(k) = k-2.  Big spreaders contribute to most of the propagation of the disease.

20% of the spreaders (blue line) cause 80% of infections (red line).
With R0 = 3.0, the transmission probability is 76% per contact.

Reducing the number of people you meet each week will slow down propagation
(see: "Quarantine the social butterflies? It can be a better way to start off flattening the curve").
Assumed contagion period for COVID-19: about one week.

For each value of R: number of contacts in a week
as a function of the transmission probability per contact.

Incubation Period.
It takes nearly a week to know if you were infected by your last social encounter.
So if you must go out again: wear a mask, no chatting with anybody and a hand sign from a distance.

Number of Flights Worldwide.

Commercial passenger flights

Sources:

Louis Marmet