, @crwells10, @abhiganit, @MeaganCFitz, @Alison_Galvani, and colleagues just had our article on optimal COVID-19 quarantine and testing strategies published @NatureComms.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
‘s preprint with @crwells10, @abhiganit, @MeaganCFitz, @Alison_Galvani, and colleagues at @biorxivpreprint was cited by @CDCgov in their Dec 2 decision to adjust quarantine recommendations in light of new analyses of the benefit of quarantine and testing. https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-options-to-reduce-quarantine.html
Coronavirus Disease 2019 (COVID-19)

CDC provides credible COVID-19 health information to the U.S.

https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-options-to-reduce-quarantine.html
We found that 1) testing later in quarantine is more effective than testing early in quarantine at preventing post-quarantine transmission, and 2) quarantine can be halved from 14 days to 7 days with a negative result from a test taken on day 6. https://www.nationalgeographic.com/science/2020/12/shorter-quarantines-could-help-prevent-coronavirus-outbreaks/?fbclid=IwAR3Uvq4eU3vSbcuG8pchVZdVnBpaXfpAO0sCYjIeKvH3n2zTcCSQDgNGw3Y
Shorter quarantines could actually help prevent COVID-19 outbreaks

Two-week quarantines strain mental health and finances. New research shows weeklong restrictions could ease this burden and improve contact tracing.

https://www.nationalgeographic.com/science/2020/12/shorter-quarantines-could-help-prevent-coronavirus-outbreaks/?fbclid=IwAR3Uvq4eU3vSbcuG8pchVZdVnBpaXfpAO0sCYjIeKvH3n2zTcCSQDgNGw3Y
Analysis of transmission pair data by He et al plus an 8.29-day incubation yields infectivity across the disease time course. Ave. # of infections from a case is still high after self-isolation of symptomatics. Silent spreading is a huge problem! https://www.nature.com/articles/s41591-020-1016-z
Author Correction: Temporal dynamics in viral shedding and transmissibility of COVID-19

https://www.nature.com/articles/s41591-020-1016-z
RT-PCR studies demonstrate declining sensitivity across the COVID-19 symptomatic disease time course.

https://faseb.onlinelibrary.wiley.com/doi/10.1096/fj.202001700RR
Much less has been learned about COVID-19 RT-PCR test sensitivity during the pre-symptomatic period which transitions from very low infectiousness to very high infectiousness just before symptom onset.
mapped an interpolation function between viral shedding v(t) from the infectivity curve to sensitivity of detection s(v).

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
The function s(v) interpolates from post-symptomatic viral shedding v(t) from the infectivity curve to provide a relationship between COVID-19 viral shedding and test sensitivity.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
used s(v), applied to the presymptomatic viral shedding v(t),
to provide a continuous function for pre-symptomatic RT-PCR sensitivity.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
did some lovely double integrals. Math does good.
https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
's data-driven analysis provides evidence that the greatest benefit of COVID-19 testing—for the purpose of safely shortening quarantine—comes from testing on exit from quarantine compared to testing on entry to quarantine.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
Compared to a 14-day COVID-19 quarantine with no testing,a 7-day quarantine with testing on exit provides equivalent or lowerprobability of post-quarantine transmission.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
Each duration of COVID-19 quarantine has a corresponding optimal day to get a test. Testing at exit in a long quarantine is near as good as testing at 7 days, so the rule of thumb of testing on exit is still great to keep in mind for longer quarantines.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
real-world tested our theory w/ offshore oil-rig workers: 47 positives were obtained with testing on entry and exit to quarantine, of which 16 had tested negative at entry; preventing an expected nine offshore transmission events—each of which would likely have led to outbreaks.
If you KNOW the day of infection and it was 7 days or more ago, the optimal test day is RIGHT AWAY. The reason the left side of these graphs dominate the optimality calculation is because there is so much more transmission to come from those who were recently infected.
Higher transmission levels such as with a lack of COVID-19 precautionary measures or with the new COVID-19 genetic variant, or higher asymptomaticity, all moderately increase post-quarantine transmission, but do not affect optimal test day.

https://www.nature.com/articles/s41467-020-20742-8.epdf?sharing_token=GA6FCqudo8iUNz3j5ToMuNRgN0jAjWel9jnR3ZoTv0OuoQWDwXvoOqvQ6JoxBthPWy_fq5wW05v-vYANCpXSxwopX978SsufJzbcAPeAzvx5JcvnQPfi-wMqhxEalwRBcUdXEV9lLlDTuzg-SjrEkYTFsXkB_mfTKQVgbpFCkf8%3D
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