Add Omicron variant
Omicron is going to be the dominant strain across Europe within a couple of weeks, I suggest we add it to CARA (with a view to it being the new default at some point v. soon). But there isn't really a solid study/resource to use (yet).
In the meantime here are the best resources I've found so far: Via Twitter from Carl Pearson in South Africa - estimate of R relative to delta at 2.4x (2-2.7, presumably 95% CI). https://twitter.com/cap1024/status/1466840869852651529 https://drive.google.com/file/d/1hA6Mec2Gq3LGqTEOj35RqSeAb_SmXpbI/view
This was cited by another group at LSHTM who are still in preprint/pre-preprint (updated 11th December) https://cmmid.github.io/topics/covid19/reports/omicron_england/report_11_dec_2021.pdf
New source (via Benoit Salvant): Omicron = 2x Delta infectiousness. https://www.medrxiv.org/content/10.1101/2021.12.14.21267755v1
5/1/22: Another source: https://onlinelibrary.wiley.com/doi/abs/10.1002/jmv.27560 with a relative R of 3.19x Delta I suggest at this stage we take a mean of these (2+2.4+3.19/3=2.53) and apply it, of course with revisions in future when we have more data and authoritative reference sources.