- Location
- London
Sorry only see it now. Had some birthday events yesterday.I am sure this below is too simplistic but perhaps Po-yu or others qualified could amend as necessary
In the nose: probably asymptomatic, and less risk of infecting others (except greater likelihood of circulating at large)
In the upper respiratory tract: major illness unlikely, more risk of infecting others (but less circulation at large)
In the lungs: serious illness likely and strong risk to infect (except presumably not circulating at large)
In sense of the progression or seriousness of covid yes we can maybe categorise to these three kinds, but transmission risk is probably more complicate than that.
As briefly expalined before, "asymptomatic" people might not be that infectious, but pre-symptomatic can be very infectious, and you couldn't tell who's real asymptomatic (no symptom all the way) until a week later. Virus in the nose and throat can be quite infectious at early point, with two factors: 1. the person feels fine and looks fine at this stage and goes around 2. droplets easily come out from nose and throat when speaking, laughing, singing....
Assumingly that's the mass majority of intection events in the communities, as *already mildly ill people have better chance to infect their households, and *already severely ill people mainly cast risk on caretakers. Actually, many seriously ill people already have little virus in their nose, but there are still lots of virus in their lung and/or the inflammation of lungs already starts, it's cytokine storm causing damage.
Since the seriousness of Covid is related to viral load (viral load at early stage can somewhat predict the outcome later on), you can kind of say those who have symptoms carry more risk of infecting others, but note that it can happen before symptoms onset. Basically, if you have more virus from the beginning, you 1. can infect others more from the beginning 2. have higher chance to be more ill later on. That is why Delta strain seems to go against evolution rule, transmiss better at the same time causing more serious illness. Data from a recent Delta strain outbreak in China shows that Delta strain generate 1000 folds higher viral load compared to the strain in 2020.