The question of how much more infectious B.1.1.7 is is pretty useless without also referencing a generation time estimate. Different agencies/countries use different values for that, so the numbers for the relative R number R_B.1.1.7 / R_old they give are not directly comparable. I expanded on this in a comment a while ago.
In the meantime, the Danish SSI also published a report in which they also stress that the numbers of how much more infectious B.1.1.7 is can’t be compared across countries due to in particular different generation times being used. This report is from January 21., and in it they estimate relative R to be 1.36 as of January 14.
A newer report from February 3. mentions that SSI now estimates a relative R for B.1.1.7 of 1.55.
The SSI uses a generation time of 4.7 days, the English PHE uses a generation time of 6.57 days.
The quoted conclusion of 37% increase in infectiousness from the original post is unfortunately a mistake, see my comment here.
The question of how much more infectious B.1.1.7 is is pretty useless without also referencing a generation time estimate.
Generally true, but in using contact tracing data the English analysis is answering the “how much more infectious” question directly rather than relying on inferring from relative growth rates and estimated generation times.
The 37% error does revise my estimate a bit for how confident I should be that it is <50% (although even correcting that it is probably still under 50% according to Zvi) but I still expect it to end up that side of the equation. If I was answering that survey now I’d be at 20% or so.
The question of how much more infectious B.1.1.7 is is pretty useless without also referencing a generation time estimate. Different agencies/countries use different values for that, so the numbers for the relative R number R_B.1.1.7 / R_old they give are not directly comparable. I expanded on this in a comment a while ago.
In the meantime, the Danish SSI also published a report in which they also stress that the numbers of how much more infectious B.1.1.7 is can’t be compared across countries due to in particular different generation times being used. This report is from January 21., and in it they estimate relative R to be 1.36 as of January 14. A newer report from February 3. mentions that SSI now estimates a relative R for B.1.1.7 of 1.55. The SSI uses a generation time of 4.7 days, the English PHE uses a generation time of 6.57 days.
The quoted conclusion of 37% increase in infectiousness from the original post is unfortunately a mistake, see my comment here.
Generally true, but in using contact tracing data the English analysis is answering the “how much more infectious” question directly rather than relying on inferring from relative growth rates and estimated generation times.
The 37% error does revise my estimate a bit for how confident I should be that it is <50% (although even correcting that it is probably still under 50% according to Zvi) but I still expect it to end up that side of the equation. If I was answering that survey now I’d be at 20% or so.