The R0 of a disease is the number of new people the disease infects, on average, in a naive population (i.e. never had the disease before)
For the #nCoV19, that number is ~2
-
-
Prikaži ovu nit
-
So, 2 new people infected per person who gets sick How does this relate to herd immunity? Well, herd immunity is what happens when enough people are immune to a disease that the reproduction rate (R) drops below 1
Prikaži ovu nit -
An R below 1 means that, on average, each person infects less than one new person, so the disease eventually stops spreading Great news right?
Prikaži ovu nit -
For different diseases, that means that you need different numbers of people vaccinated to prevent transmission The formula is pretty simple - (R0-1)/R0 = % immune required
Prikaži ovu nit -
For the coronavirus, that would mean that (2-1)/2 = 50% of the population would need to be vaccinated to prevent spread of the disease, on average (it's not that infectious!) For measles, with an R0 of 15-18, the number is 92-95%!
Prikaži ovu nit -
You can also reduce the effective reproduction rate, R, using other measures like quarantining sick people, which is what we're doing now
Prikaži ovu nit -
P.S. you can also see populations reaching herd immunity if enough people catch a disease, but this has the disadvantage of lots of people getting sick which is why we vaccinate
#VaccinesWorkPrikaži ovu nit -
Oh, also if we took the R0 of 3.8 that's been the highest estimate for the coronavirus (and sprouted the infamous PANIC THERMONUCLEAR PANDEMIC tweet), the % vaccinated would have to be (3.8-1)/2.8 = 74% vaccinated to reach herd immunity
Prikaži ovu nit -
(Above tweet should read (3.8-1)/3.8 = 74%, sorry about the typo)
Prikaži ovu nit
Kraj razgovora
Novi razgovor -
-
-
Doesn't a high CFR also decrease R0, and therefore increase effective herd immunity?
-
Depends. I.e. can have a high CFR but long disease progression. Also depends a lot on the place that the disease is spreading
- Još 2 druga odgovora
Novi razgovor -
Čini se da učitavanje traje već neko vrijeme.
Twitter je možda preopterećen ili ima kratkotrajnih poteškoća u radu. Pokušajte ponovno ili potražite dodatne informacije u odjeljku Status Twittera.