There's fringe theories out there that the vaccines are causing amplification of the virus in at least a small percentage of people, either leading to vaccine failure or causing them to be asymptomatic but shed huge/amplified amounts of the virus or become Typhoid-mary-like permacarriers, and that this is actually what's driving the summer outbreaks, which is being blamed on the delta variant. It also would account for the push to make everyone get vaccinated, because if everyone is vaccinated then it becomes harder to identify any such problem with the vaccine, because there's no control group left. And it also explains the sudden and basically unexplained reversion to asking vaccinated people to wear masks again. The problem with the theory is that outbreaks still seem to be hitting unvaccinated people heavily. Although the CDC's incompetence in reporting any intelligible numbers, or tracking the effectiveness of the vaccines in any way that would answer people's concerns doesn't help with disproving these theories.