This page collects observations, interpretations, and consequences for action about Contagiousness of SARS-CoV2. Please observe the structure of the page, when you add your content. Please use references where possible. Remember to find the relevant page. For example, if your observation is about Sources, please use that page, instead of posting your content here.
What is already known
- The earliest most probable SARS-like serial interval scenarios resulted in an estimated R0 of 2 - 2.7 (90% CrI) 
- The R0 was estimated as 2.2,8 3.8,11 and 2.6812 by different research all round the world. The WHO published an estimated R0 of 1.4 to 2.5. 
- The median incubation period of 2019-nCoV is found to be 5.2 days (95% CI: 4.4, 6.0), and 97.5% of those who develop symptoms will do so within 10.5 days (95% CI: 7.3, 15.3) of infection. It is estimated that a very small proportion (64 out of every 10,000 cases) will develop symptoms after 14 days of active monitoring or quarantine. 
- Analyses of data from China as well as data from those returning on repatriation flights suggest that 40-50% of infections were not identified as cases12. This may include asymptomatic infections, mild disease and a level of under-ascertainment. 
- Patients with severe COVID-19 tend to have a high viral load and a long virus-shedding period. This finding suggests that the viral load of SARS-CoV-2 might be a useful marker for assessing disease severity and prognosis. 
- A study among COVID19 survivors in China showed that 5 out of 147 started to test positive again for SARS-CoV2 after having fully recovered and after having tested negative repeatedly.
- The finding in Wuhan that survivors start testing positive again could point towards a possible carrier stage, but it could also simply point to re-contamination, as the positive test is PCR.
Consequences for action
- More studies are needed to understand viral shedding after recovery, before we consider consequences to this observation
- Abbott, Sam, et al. "The transmissibility of novel Coronavirus in the early stages of the 2019-20 outbreak in Wuhan: Exploring initial point-source exposure sizes and durations using scenario analysis." Wellcome Open Research 5.17 (2020): 17.
- Fang, Yaqing, Yiting Nie, and Marshare Penny. "Transmission dynamics of the COVID‐19 outbreak and effectiveness of government interventions: A data‐driven analysis." Journal of Medical Virology (2020).
- Lauer, S. A., Grantz, K. H., Bi, Q., Jones, F. K., Zheng, Q., Meredith, H., ... & Lessler, J. (2020). The incubation period of 2019-nCoV from publicly reported confirmed cases: estimation and application. medRxiv.
- Ferguson, N. M., Laydon, D., Nedjati-Gilani, G., Imai, N., Ainslie, K., Baguelin, M., ... & Dighe, A. (2020). Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand. Imperial College, London. DOI: https://doi. org/10.25561/77482.
- Liu, Y., Yan, L. M., Wan, L., Xiang, T. X., Le, A., Liu, J. M., ... & Zhang, W. (2020). Viral dynamics in mild and severe cases of COVID-19. The Lancet Infectious Diseases.
- China reports deeply disturbing coronavirus development Digital Staff 7NEWS Friday, 27 March 2020 6:45 am https://7news.com.au/lifestyle/healthmedicine/china-reports-deeply-disturbing-coronavirus-development-c-765460.amp?utm_campaign=share-icons&utm_source=twitter&utm_medium=social&tid=1585264794990&__twitter_impression=true