Thread by @firefoxx66

Please have a look at our latest paper out today on medRXiv: "Impact of seasonal forcing on a potential #SARSCoV2 pandemic"
We (@richardneher @Jan_Albert_ @robert_dyrdak Valentin Druelle) worked at lightening speed to get this out... #COVID2019 #nCoV2019
medrxiv.org/content/10.110…

'Seasonal' coronaviruses circulate annually & cause common colds in winter. We used data of these seasonal CoVs to calibrate a model recreating the observed pattern in seasonality.

We found it could recreate observed seasonality (yellow boxes) with either low case import and low seasonal forcing, or high case import & a range of medium-to-high seasonal forcing. Since most countries are now highly connected, we focus on high-import model.

We then switch from endemic to pandemic model - we /assume/ a pandemic occurs for this analysis!
*Important* to go see paper for model details!

Modelling import from a Hubei 'deme' we varied the 'peak transmissibility month' in a Northern Europe setting.

*IF* a pandemic were to occur, we find that peak transmissibility time impacts epidemic dynamics.

If a winter peak month (Jan/Nov, pink/purple below), we could see a double-peak or delayed-peak in # cases.
We could falsely think pandemic is over, or under control...
#SARSCoV2

We re-ran 1000x with sub-pops in North, Tropical, & South, varying exact parameters (see paper). We find dynamics are variable, & global prevalence decays only slowly through 2020 & 2021.

Finally we looked at whether #SARSCoV2 could transition to an endemic seasonal virus.
Assuming people can be reinfected after 10 years, we find this is possible, with a seasonal prevalence much lower than peak pandemic prevalence.

Main take-aways:
1. Case count decreases could be due to seasonality rather than interventions - we should be cautious
2. Dynamics could vary greatly - don't rely too heavily on other countries' trajectories
(cont'd..)
#SARSCoV2 #COVID19

(...cont'd)
3. Seasonality might slow a pandemic in summer months providing an opportunity to better prepare healthcare systems
4. #SARSCoV2 could become endemic in medium term, similar to 2009 H1N1 transition
#COVID19

We explore more parameter values & explain model more fully, in our Supplemental Materials - please have a look!
medrxiv.org/content/10.110…

Data & code available on Github so you can explore this further yourself, as well. #openscience #opendata
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