This is an interesting paper covering the topic of contact tracing and isolation, and the case for doing this with mobile technology (a very persuasive one). Rather than me summarizing the paper, I’ll let the authors, since this is the era of social scientists.
Of note, they do not believe asymptomatic transmission is very significant:
Therefore, the large fraction of traceable transmission in Singapore does not contradict the large fraction without symptomatic exposure in Wuhan. However, it does suggest that transmission from asymptomatic, rather than pre-symptomatic, individuals is not a major driver of spread.Ferretti L, Wymant C, Kendall M, Zhao L, Nurtay A, Abeler-Dörner L, et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science (80- ) [Internet]. 2020;eabb6936. Available from: https://www.sciencemag.org/lookup/doi/10.1126/science.abb6936
They have set up a web site where people can look at the the impacts of changing the parameters of their model here, with a great title: See: Coronavirus Fraser Group: It is possible to stop the epidemic
“Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing” https://t.co/a8HQZuhsfE 1/ pic.twitter.com/VnD88sWinL
— Christophe Fraser (@ChristoPhraser) April 4, 2020
Apps are in development
Here’s a list of links with stories about this concept as well as to apps under development
Ferretti L, Wymant C, Kendall M, Zhao L, Nurtay A, Abeler-Dörner L, et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science (80- ) [Internet]. 2020;eabb6936. Available from: https://www.sciencemag.org/lookup/doi/10.1126/science.abb6936
Whoa! “asymptomatic, rather than pre-symptomatic, individuals” –
I’ve never seen those two separated. Pre seems to connote “they later started showing symptoms,” so I can only imagine that asymptomatic means “had the infection but never showed any symptoms, i.e. never got sick.” Is that correct?
If so, I guess I’m not surprised, but I’m pretty sure people have been mixing the two. Like, the news reports about the Georgia governor make no distinction at all between “a-” or “pre-.”
Okay, so I click through and see they propose 4 types of transmission…. snip snip:
I. Symptomatic transmission: direct transmission from a symptomatic individual, through a contact that can be readily recalled by the recipient.
II. Pre-symptomatic transmission: direct transmission from an individual that occurs before the source individual experiences noticeable symptoms. …
III. Asymptomatic transmission: direct transmission from individuals who never experience noticeable symptoms. …
IV. Environmental transmission: transmission via contamination …
So, assuming people like Georgia gov and all those reporters (and me) don’t know the difference, why is it “of note” that people who never get sick seem to not be a big factor?
Anyway, I’m all for the closing line:
“We recommend urgent exploration of means for intelligent physical distancing via digital contact tracing.”
Yes, before reading this piece there was confusion in my mind, too. I suppose with this model, most people who transmit the virus are going to eventually show symptoms, which is good because they could report them on their phone and then close contacts would know to isolate. Fully asymptomatic people wouldn’t have this warning for close contacts.
I’m postulating that because we aren’t doing contact tracing right now, we aren’t fully exploring the idea that maybe it’s not asymptomatic people who are transmitting virus. Reality is that people aren’t going to remember (or want to reveal) who they’ve been in contact with so this could be the dominant form of transmission but the only way to deal with it right now is a stay at home order (where people can infect whole households…). Let’s keep learning together,