(07-26-2021, 09:38 AM)homebiscuit Wrote: I'm really interested in finding out the viral load and transmissibility with vaccinated people and the Delta variant.

This study went to publishing last week and covers a 17 week period. I haven't fully digested it yet, but it shows the significant benefits of vaccination in those who acquire a "breakthrough" infection. I don't think it includes discussion of the variants, but it's still relatively good news.

https://www.nejm.org/doi/full/10.1056/NE...tured_home

Here's the big takeaways:

In a prospective cohort study involving 3975 health care personnel, first responders, and other essential and frontline workers followed over 17 weeks in six U.S. states, the effectiveness of the mRNA vaccines BNT162b2 and mRNA-1273 in preventing symptomatic and asymptomatic RT-PCR–confirmed SARS-CoV-2 infection was 91% (95% CI, 76 to 97) with full vaccination; vaccine effectiveness was 81% with partial vaccination. These estimates of vaccine effectiveness in real-world conditions are consistent with findings from efficacy trials[font=ff-quadraat-web-pro,]1,2 and from a similar prospective study involving health care personnel in which routine SARS-CoV-2 testing was also conducted.7[/font]

Among the small number of participants with breakthrough RT-PCR–confirmed SARS-CoV-2 infection despite vaccination, the mRNA vaccines appeared to attenuate infection and disease in multiple ways. Participants who were partially or fully vaccinated at the time of infection had a 40% lower viral RNA load and a 66% lower risk of viral RNA detection for more than 1 week than participants who were unvaccinated at infection. Partially or fully vaccinated participants also had a 58% lower risk of febrile symptoms and a shorter duration of illness, with approximately 6 fewer days of symptoms and 2 fewer days spent sick in bed, than unvaccinated participants. The observed presence of a reduced viral RNA load after the administration of mRNA vaccines is consistent with findings in a recent report,[font=ff-quadraat-web-pro,]8 and the observed combination of virologic and clinical effects is consistent with previous findings of a lower level and shorter duration of viral RNA detection with milder Covid-19.9[/font]

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