At this point, the countries with most genomic data to analyze spread of the variant virus belonging to https://t.co/ImaHU6Jxdv B.1.1.7 lineage or @nextstrain clade 20I/501Y.V1 are the UK, Denmark and the USA. Here I compare growth rates of B.1.17 across these countries. 1/13

Working from @GISAID data, the UK has 18776 genomes, Denmark has 6089 genomes and the USA has 3093 genomes from specimens collected after Dec 15, 2020. Here, I'm looking at daily genomes with collection dates up to Jan 6 that were not pre-screened by "S dropout". 2/13

For the UK, we can see a steady increase in the frequency of sequenced variant viruses belonging to the B.1.1.7 lineage, reaching ~70% frequency at the end of December. Solid line is a 7 day sliding window average. 3/13

We can fit a logistic growth model to the frequency of B.1.1.7 in the UK data to estimate the rate of frequency increase through time. 4/13

And following @erikmvolz et al (https://t.co/l2ElhJVk8b) we can convert from a measured frequency growth rate to an estimate of increased transmissibility by assuming a particular generation time, which I take to be between 5 days and 6.5 days. 5/13