Virus vaccines are of limited usefulness in the best of years. They are prepared from last year’s variant which will reappear as yet a new variant against which the new vax is only spottily effective.
The best vaccine out there is the one YOUR body prepares as soon as it encounters a virus in body. It is called anti-body.
But not all people can create equal amounts of anti-bodies. Those who are younger, and those who exercise regularly, and those who eat nutritious food, and those who don’t smoke or drink more than 1 drink a day, or those who get enough sleep every day, can create sufficient anti-bodies to vanquish most invading viruses, INCLUDING COVID-19.
That is why many people who get infected never get sick, they get well without symptoms, and they test positive for covid-19 anti-bodies presence.