Some recent credible studies from the UK suggest that the variant B.1.1.7 which was first detected there is not only more transmissible but associated with greater severity, measured by deaths. A thread 1/n

The studies on which this is based are summarized in this document. Notably, it is not founded on one study, but several. They incorporate different data, methods and different biases and they are all imperfect, but they point in the same direction. https://t.co/W7fwAxlNrQ 2/n

The upshot is that people infected with B.1.1.7 are about one third more likely to die than similar people infected with the pre-existing viral lineages. There is a LOT of uncertainty around that number. For a lot of reasons. But some increase (even if small) seems legit 3/n

This is consistent with early statements that there was not a large change in virulence. You would not expect to detect a 30% increase from the data available early on (I seem to remember saying there might be some change but not enough to be detected by the current data) 4/n

Of course, if a large number become infected, then a 30% increase really really matters in terms of the absolute numbers of deaths. Instead of the 400k + deaths in the US, we would have 520k+ were they due to a virus like this (<-toy example please don't quote out of context) 5/n