That is a very old study and an unusual one: the carrier was an admitted hospital patient (for a chest condition) who tested positive and was put in quarantine, and the 455 contacts were based on contact tracing during her stay at the hospital - hospital staff, other patients, close family. Your second cite also follows an asymptomatic carrier who tested positive and isolated despite having no symptoms.
Think about that for a second, these studies involve asymptomatic individuals who tested positive by coincidence and were put under strict isolation. In that specific scenario, transmission is negligible.
We’re talking about the general case and public policy here. Most people without symptoms do not get tested for the virus, and therefore have no cause to isolate. Unless you regularly get tested for the virus and promise to isolate if the test comes back positive, these studies have no bearing on Euphonious_Polemic and Gorsnak’s point.
By and large asymptomatic individuals with COVID-19 can transmit the virus, not as well as symptomatic carriers, but still at a significant rate. If you’re going into the literature I found a December meta-study that reviewed five studies covering transmission rates of asymptomatic individuals, Estimating the extent of asymptomatic COVID-19 and its potential for community transmission: Systematic review and meta-analysis | Official Journal of the Association of Medical Microbiology and Infectious Disease Canada. Here is a reproduction of table 2,
Table 2: Comparison of secondary transmission rates
||No./ N (%) Asymptomatic transmission rate
||Symptomatic transmission rate
|Zhang et al (22)
|Cheng et al (14)
|Chaw et al (13)
|Luo et al (17)
|Park et al (18)
Quote from the meta study,
The asymptomatic transmission rates ranged from none to 2.2%, whereas symptomatic transmission rates ranged between 0.8% and 15.4%.
Now to take these numbers and make them tangible… if I am misinterpreting data feel free to point it out - I’m bad with statistics! Pretend you are an asymptomatic, unvaccinated carrier. You have normal contact with another unvaccinated person (with normal precautions, eg: a face covering all of the time and six feet distancing most of the time). The data would indicate that there may be up to a 2.2% chance that you infect the person (it would be higher without precautions - I’ve seen estimates in the double digits).
All of this concerns asymptomatic individuals, not to be confused with presymptomatic individuals. It is known that the virus can be transmitted before the onset of symptoms, and this was an early distinguishing feature between SARS-CoV-2 and SARS-CoV-1. Presymptomatic carriers, and not asymptomatic carriers, are thought to be the most contageous. Meaning, if you end up having symptoms you could have been transmitting the virus before you knew you were sick. Those people are not included in asymptomatic studies. But I am not able to find a meta study on the transmission rate. Maybe someone else more knowledgeable can find those numbers, or point you to the individual studies that we can rely on.