This episode is also available as a blog post: https://ourfiniteworld.com/2021/08/05/covid-19-vaccines-dont-really-work-as-hoped/

In early August, the CDC announced a surprising finding: “Delta infection resulted in similarly high SARS-CoV-2 viral loads in vaccinated and unvaccinated people.” Public officials had known from the early days of vaccine development that vaccinated people could catch COVID-19, but the assumption had been made that they were not going to be spreaders of COVID-19.

It turns out that the delta variant is sufficiently different from the original Wuhan version of the virus that the vaccines work much less well.