My casual understanding was that there werent really any asymptomatic spreaders, just "not symptomatic yet". Is this wrong?
I, asymptotic young person with nCoV 2, am spreading it today. The “yet” part is completely irrelevant to this point in time.
In colloquial usage, asymptomatic encompasses presymptomatic. In technical usage, they are different.
If you develop symptoms, then when you were a carrier before then, you were presymptomatic, rather than asymptomatic.
Of course, whether you go on to develop symptoms or not, its still highly pertinent information if asymptomatic spread is not a major driver of infection. As long as you self isolate upon symptom onset that should be enough. It does call into question whether isolating the apparently healthy is an evidence-based public health policy intervention though.
And the viral load is high two days before the symptoms onset. If you want a proper RCT about it, good luck approving it in an ethics committee.
We used to think true asymptomatic infections (never develop any symptoms but test positive) were ~50% of those infected. More recent research puts it at closer to ~20%. Again, some reporting bungled this by reporting studies from controlled populations (like a cruise ship) before they knew if cases were asymptomatic or pre-symptomatic, causing people to quote the number as the former, when it was really a mix.
COVID spreads like wildfire by pre-symptomatic people. There are mountains of evidence to support this. Spread by asymptomatic people is speculation.
> Of course, whether you go on to develop symptoms or not, its still highly pertinent information if asymptomatic spread is not a major driver of infection.
Not sure, but I think you may be using the word "asymptomatic" to denote pre-symptomatic in this sentence.
> As long as you self isolate upon symptom onset that should be enough.
It is not enough.
There is absolutely a difference between 'yet to have' and 'never will have' but I think it is potentially confusing to attempt to delineate between asymptomatic and "pre-symptomatic".
The main concern with messaging that causes confusion in this regard is that a superficial reading of "asymptomatic doesn't spread virus" would imply that if you aren't symptomatic, you aren't a danger.