Eh, which thread was that info. posted in? Your vaccinations thread?
A key question would be, does Delta shed so heavily from asymptomatic (or mildly symptomatic) carriers?
Thanks.
From Yesterday’s thread:
“Good explanation of Delta infectiousness.
https://twitter.com/angie_rasmussen/status/1415672461111271424“
“... This study attempted to address this in quarantined close contacts of confirmed cases. These people were tested daily by PCR, which allowed the investigators to determine the course of infection: longitudinal viral loads and time from exposure to positivity and symptoms...”
“delta is not more transmissible by the aerosol route than other variants. Primary modes of transmission continue to be a mix of inhaled aerosols and direct contact. “
“-People infected with delta test positive more quickly following exposure, suggesting more rapid viral growth.
-The viral loads (by PCR Ct) are 1000 times higher in delta “
“This suggests that the delta incubation period is reduced compared to the prior viruses. Also, people infected with delta are shedding a s&!t-ton more virus than those from earlier variants.”
“This study suggests that the mechanism behind delta’s increased transmissibility is just that there’s a lot more of it, sooner.”
“Unvaccinated people are most vulnerable.
Partially vaccinated people are slightly less vulnerable but not robustly protected.
Fully vaccinated people are very protected.”
“It also explains breakthrough infections. No vaccine is perfect, and a high enough dose of virus can overcome vaccine-induced defenses enough to cause an infection, though vaccine-induced immunity will limit disease severity in most cases.”
“Nothing is known about whether delta is more pathogenic.”
“More transmissible VOCs (Variants Of Concern) may appear to be more pathogenic based on just infecting more people, who may be uniquely vulnerable.”
That ends the Twitter comments that I extracted.
Here is the original study it discussed: https://virological.org/t/viral-infection-and-transmission-in-a-large-well-traced-outbreak-caused-by-the-delta-sars-cov-2-variant/724
It mentioned three mutations (I thought it was two, and a different Indian variant had the three) - “sublineage, B.1.617.2, with spike protein mutations L452R, T478K and P681R”.
In response to your question about asymptomatic spread, it seems they could not tell, in this study: “critical parameters before the illness onset remain elusive, including when the viruses can be detected in a subject after exposure and how infectious they are.”
“the time interval from the exposure to first PCR positive in the quarantined population” (was about 4 days, instead of 6, which earlier strains showed).
They did mention that generally (prior to Delta) over 50% of transmission occurred in the pre-symptomatic stage of infection.
“A potential higher viral replication rate of the Delta variant is proposed, which leads the viral loads in Delta infections to be ~1000 times higher than the 19A/19B strains infections on the day when the testing turns to be positive. This highlights more infectiousness of Delta variant during the early stage of infection is very likely, and the frequency of the population screening should be optimized for the intervention.”
In the end, they do say that Delta is more infectious (than the original strain) before symptoms appear:
“The more infectiousness of the Delta variant infections in pre-symptomatic phase highlights the need of timely quarantine for the suspicious infection cases or closely contacts before the clinical onset or the PCR screening.”