Modeling layered non-pharmaceutical interventions against SARS-CoV-2 in the United States with Corvid

Dennis L Chao; Assaf P Oron; Devabhaktuni Srikrishna; Michael Famulare

For the incubation period distribution (duration from infection to showing symptoms), we used the log-normal fit from [24] who used data from Shenzhen. They found parameters of log(mean)=1.621 and log(sd)=0.418 (Figure 8 ). There are reports that viral detection peaks a few days after symptoms. [25] found pharyngeal shedding to peak 4 days after symptoms using throat swabs. Therefore, we used the incubation period distribution and added 4 to the mean (the log(mean) of the distribution is log(exp(1.621)+4)). That makes shedding peak 4 days after the median incubation period (Figure 8 ). It might make more sense for shedding to peak right after symptoms appear in an individual instead of independent of symptom onset. We assume that shedding lasts for 21 days, though the level of shedding is low by the end of the infectious period. We make asymptomatic individuals half as infectious as symptomatic. So if a person never becomes symptomatic, infectiousness is simply half that of a symptomatic individual over time. If a person becomes . CC-BY 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.