There was so much craziness re Covid, but one thing with profound implications for everything around the vaccine was the timing of someone being considered "vaccinated."

For the mRNA jabs, you weren't considered fully vaccinated until 2 weeks after your second shot.

Most side effects are concentrated in the days immediately after vaccination, so all thing things that happened in that window
- covid cases
- covid deaths
- strokes
- heart attacks
- (etc)

were attributed to someone being unvaccinated (or partially vaccinated).

It's hard to overstate the effect of this on the statistics around the effectiveness of the shots. Basically most of negative effects of the shots are falsely attributed to the lack of them.