Can a higher use of a vaccine (pfizer) wear it's effectiveness against a variant?
Every time a virus enters the cells of our bodies, it replicates itself, and during that replication small errors can occur called mutations, which become part of the new virus. Many of these mutations aren't noticeable, but sometimes a virus gets several mutations that make it act a little differently from the original virus, and we call that a variant. Many variants may be no more harmful than the original virus, but scientists are always watching to discover any variants that are better at entering our cells, causing severe symptoms, or being transmitted to another person. So far, the current vaccine is protecting us pretty well from all the variants that have developed. Scientists are still researching whether a booster shot would help them fight off the newest variants.
This production of variants can only occur within a body, so the more people who get infected, the greater the chance for new variants to appear. This is one of the reasons we are concerned about the virus spreading throughout the community. Even if the infected people have only mild cases, they can still act as the host where a new harmful variant develops and is transmitted to other people where it may cause more serious disease.
When the vaccine was first made, some people suggested we should delay the second dose so that more people could quickly get a chance at a first dose. But some scientists were concerned that in a person with just one dose of vaccine, the virus would be able to mutate more quickly. Not all scientists thought this was likely, but all agreed that it was a minor problem compared to the need to decrease viral replication in the community as a whole, and so the focus was on fully vaccinating people as quickly as possible.
If vaccines promoted development of variants, like you suggested earlier, we'd expect most variants to form in places where most people were vaccinated, like Israel, UK and US. But the serious variants we have first appeared in India, South Africa and Brazil where rates of vaccination are much lower.
