CADDE preprint. A SARS-CoV-2 lineage of concern is growing rapidly in Manaus and across Brazil. Using a combination of genomic and epidemiological data, we characterise the emergence and altered characteristics of this new variant, P.1. Here is a short thread of our findings. 1/8 
What makes P.1 different? The lineage has an unusually high number of mutations, including some previously implicated as important in other variants - including a trio in the spike protein (K417T, E484K & N501Y) associated with increased binding to the human ACE2 receptor. 2/8
Where did P.1 come from? Dating analyses show that this lineage emerged around early Nov 2020, in Manaus. In the weeks and months since it emerged, it has spread to multiple other states in Brazil; broadly following patterns in air travel. 3/8
We can use qPCR cycle thresholds to assess whether infections with the variant are associated with higher viral loads (the amount of virus). Roughly, Ct values are lower when the viral load is high. We see some limited evidence of this…4/8
...but sample sizes are small & not statistically significant when we control for other factors such as the delay between symptom onset and being tested. While there are interesting patterns we cannot conclude anything decisive yet. 5/8
Using a modelling approach, we find that P.1 is likely more transmissible & also likely has some ability to evade protective immunity from previous infection. We can’t tell how much of both yet, but we are confident that some degree of both has occurred. More data is needed! 6/8
Genomic surveillance is the only reason why we can identify lineages of concern like P.1. More of it needs to be done. Bottom line, until equitable access to effective vaccines is available to all, interventions should continue to play an important role. 7/8
This paper has been submitted to a journal & medRxiv. To facilitate timely & rapid open access, code, results, paper & the underlying datasets are freely available online: caddecentre.org/publications @imtspusp @AgenciaFAPESP @The_MRC @imperialcollege @uni_copenhagen @CaddeProject
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