This has been my number one concern since November 8, 2016. I honestly didn't think we'd make it alive to 2021. I breathed a huge sigh of relief when I was proven wrong. Turns out I may have sighed too soon.
No part of the MoCA is difficult. Everyone is supposed to "ace" it. The fact that he found parts of it difficult means he probably barely passed it. He's telling on himself.
It's the MoCA, you can see sample tests online. He's really telling on himself when he says the questions at the end are really difficult. No part of that test is really difficult. So, he's basically admitting he barely passed it.
Community-wide vaccination also provides further protection for individuals who ARE themselves vaccinated. The best protection against a contagious disease is to never encounter it in the first place. Vaccinating a certain percentage of the population achieves this. For everyone.