New (short) preprint on B117: “Densely sampled viral trajectories suggest longer duration of acute infection with B.1.1.7 variant relative to non-B.1.1.7 SARS-CoV-2” https://dash.harvard.edu/handle/1/37366884

Why is B117 more transmissible? Some ideas include enhanced ACE-2 binding and higher or more persistent amount of virus. We looked at longitudinal PCR tests from a cohort of 65 individuals infected with SARS-CoV-2 undergoing frequent testing, including 7 infected with B117.

Using approach as in https://www.medrxiv.org/content/10.1101/2020.10.21.20217042v2, we estimated proliferation time, peak Ct, clearance time, & duration of infection. Infection duration looked longer for B117, mean 13.3 days (90% CI 10.1, 16.5), compared to non-B117 8.2d (6.5, 9.7).

We saw no diff in peak Ct. Hard to know what to make of the slower rise in proliferation phase and slower decline in clearance phase, but suggests higher Ct for longer. (Note we fit to a "tent" model for infection.)

Since there were only 7 cases of B117, we’re cautious about interpretation. Following a great rec from @DanLarremore, we reanalyzed using with serial leave-one-out, and diff in infection duration signal seems consistent.

Feedback very welcome! Data and code available https://github.com/skissler/CtTrajectories_B117

And of course, if others have similar data on B.1.1.7 cases, it’ll be great to look into whether this holds up. We would also expect a longer serial interval, and analysis of the epi data will help evaluate whether this is the case.

Great work from a great team, led by @StephenKissler, @cdefilippomack and IQVIA team, @JosephFauver @NathanGrubaugh and team @YaleSPH, among others!