I haven't come across many answers to seemingly simple question: what are the main channels of transmission for non-symptomatic carriers of the infection? Of those two subgroups of cases are: pre-symptomatic, i.e. before symptoms develop; and asymptomatic, where no symptoms develop at all (thus can be seen as a limit case of the pre-symptomatic case). It must be relatively straightforward to recruit volunteers in both groups and measure transmission over different channels (e.g. air; surfaces; water etc) in these cases, that could help significantly in developing epidemiological models. If someone has come across such results, a reference would be much appreciated.
If someone else is looking for these answers, here's some partial ones.
1. Cough and sneezing can propel droplets farther than previously thought (i.e. beyond 2m): https://www.cbc.ca/news/technology/droplet-transmission-1.5549547
2. Talking especially more loud produces measurable exhalation of droplets that is suppressed by a wet clothmask: Article Visualizing Speech-Generated Oral Fluid Droplets with Laser ...
Still needs answers: the effect of regular exhalation? contagious content distribution with and without symptoms. Imv these findings strengthen the case for non-symptomatic transmission in "dense" environments such as close working environments, parties, nursing homes etc where viral load can accumulate over considerable time. But what about accidental encounters? The answer must be out somewhere.
Interesting and very good idea that needs to be explored. I think this is the big issue in the world where we can't separate the asymptomatic cases from the community.
Certainly, on the assumption that the cases with symptoms would be controlled the non-symptomatic channel appears to be important. There are two different aspects, or channels in this case: transmission in a close, regular environment such as a workplace or care home; it seems to be confirmed by available data that it can be significant. What is less known is the likelihood of a casual transmission during a short-time, accidental contact like in public transport. Identifying the answer could direct the policy, perhaps to focus more on protecting vulnerable people and environments, rather than uniform population-wide measures.
The best analysis yet with some further references on asymptomatic transmission:
https://www.erinbromage.com/post/the-risks-know-them-avoid-them