Unfortunately, we have reason to believe that over time, the immune defenses from COVID-19 infection seem to decline, particularly in older folks. It'd be great if we had some definitive data on secondary infection rates, but until a lot more people get infected, we just won't have it.
I think this is another case where improved surveillance is turning up things that, while they look bad, happen with other vaccines and never turn out to be a problem.
The same goes for variants, which a lot of people expect to break through vaccines because that's how the flu works, but it doesn't actually seem like they will.
