My university has become a pretty interesting case study in lockdown vs vaccines or alpha vs delta:
(all data taken from:
https://coronavirus.duke.edu/covid-testing/)
Fall 2020: most classes online. Some lab classes in-person. Research students aren't full-time in lab. Most campus restaurants closed, others are pick-up only. Indoor masking, pretty strict. No outdoor groups. No vaccinations. Alpha variant.
Over
4.5 months,
240 cases (both those who tested positive and also 150 who were contact-traced).
Spring 2021: Same situation with classes, but research students have returned mostly. Same situation with campus restaurants as before, but indoor masking rules a little more relaxed if eating far apart from others, and eating is allowed in groups outdoors. Alpha variant, very few vaccinated at the start, a solid chunk vaccinated by the end.
Over
4 months,
935 cases (including 500 that were contact-traced). A big cluster of a few hundred cases was linked to an off-campus party.
Fall 2021: A supposed indoor mask mandate but also indoor eating allowed. All restaurants open. Many classes in-person. All research students back in their labs. 95% vaccination rate. Delta.
350 positives in
2 weeks (and that doesn't include contact-tracing I think).
Either delta is that much worse, or vaccinations are really poor on transmission, or lockdowns were the holy grail.