[pfg]

That quote is slightly misleading. It only looks at the SAR of vaccinated index cases. That makes sense because the letter is about the epidemiological relevance of vaccinated people, but it's incorrect to say vaccines had no effect on SAR: The study those figures were taken from also states that "The SAR in household contacts exposed to the delta variant was 25% (95% CI 18–33) for fully vaccinated individuals compared with 38% (24–53) in unvaccinated individuals."

A study based on data from Singapore found a similar effect[1].

[1]: https://www.thelancet.com/journals/lanwpc/article/PIIS2666-6...