The earliest swabs were taken on day 1 of symptoms,
with symptoms often being very mild or prodromal.
[...]
In all
patients except one, throat swab RNA concentrations seemed to be already on the decline at
the time of first presentation.
BTW, my speculation of how presymptomatic transmission happens is that, in addition to droplets caused by normal speaking, during that time the virus also causes very mild itching/tingling in the throat, which causes very mild coughs (throat clearings) that don’t even get noticed as symptoms. (This is based on a family member having a cold recently, and me noticing such very mild symptoms in myself that I probably wouldn’t have noticed if I hadn’t been looking for them.)
ETA: The above linked paper is also interesting for these reasons:
Together,
these data indicate active replication of SARS-CoV-2 in the throat during the first 5 days after
symptoms onset.
When aligned to viral load courses, it seems there is no abrupt virus elimination at the time of
seroconversion. Rather, seroconversion early in week 2 coincides with a slow but steady
decline of sputum viral load. Whether certain properties such as glycosylation pattern at
critical sites of the glycoprotein play a role in the attenuation of neutralizing antibody
response needs further clarification. In any case, vaccine approaches targeting mainly the
induction of antibody responses should aim to induce particularly strong antibody responses
in order to be effective.
Additional evidence:
BTW, my speculation of how presymptomatic transmission happens is that, in addition to droplets caused by normal speaking, during that time the virus also causes very mild itching/tingling in the throat, which causes very mild coughs (throat clearings) that don’t even get noticed as symptoms. (This is based on a family member having a cold recently, and me noticing such very mild symptoms in myself that I probably wouldn’t have noticed if I hadn’t been looking for them.)
ETA: The above linked paper is also interesting for these reasons: