🧵US cases are declining significantly. Should we be surprised? No. New infections arise from this formula for R:
R = D x O x T x S
D = Duration (time infectious)
O = Opportunities (contacts/day)
T = Transmission (probability infect contact)
S = Susceptible (proportion of popn)
2/ One of those factors, S, has been changing significantly over the past year because the US has had many more infections per capita than Canada.
In fact, previously infected are now about 30% of the population. Vaccinated (2 dose) are now ~ 6%. npr.org/sections/healt…
3/ If we now go back to R = DOTS, we get
R = DOT x (1 - .3 -.06)
If DOT stays about the same, then R drops to 64% of what is was when everyone was susceptible. An original R of 1.25 becomes .8. A "new R" of .8 is going to drive cases down because 100 infections cause 80 new ones.
🧵🦠📈 Canada Overnight Update
~ vaccines, provinces, regions ~
Canada's weekly case rate is now at 54.7. The week/week decline is down to -5.6%. More ⤵️ #Covid19#cdnpoli
💡explore in the viz at bit.ly/Billius27
🧵Smoothing trends. This mathematical method attempts to understand the underlying trends in daily data and is a little different than 7 day averages. It is detecting "up" signals in Alberta, Manitoba, and Ontario. More ⤵️
Newfoundland's B117 variant outbreak shows how strong upward spikes can be.
Smaller populations like Nunavut cab have more erratic patterns around outbreaks.
🧵🦠📈 Canada PHU Update Feb 20
~ provinces, regions ~
Weekly case rate drops to 53.9, down 11.2% from last week. The rate of decline is slowing. #Covid19#cdnpoli
💡explore in the viz at bit.ly/Billius27
Canada's administered doses hit a daily record of 47,707 as supply expands.
Weekly shipments are expected to remain high and continue ramping up. The target remains 6 million doses by the end of March.