Do Vaccines and Tests Prevent mass spreading of COVID-19?

I was skeptical initially about such outdoor concerts where 100,000 people come together in close proximity (and yes, without masks) How would they prevent the spread of COVID-19?

I must admit — I was wrong.

This sold-out concert required full COVID-19 vaccination or a negative test will be required to enjoy the festivities, and in retrospective, 200+ people were infected after…