Vaccines do not cause variants to develop. In fact, vaccines can help slow the spread of COVID-19 and reduce the development of new variants. COVID-19 variants, like omicron and its subvariants XBB.1, BA.5, and BA.4, are caused by mutations in the virus’ genetic code. Mutations happen when the virus makes copies of itself (replication) and infects people. Vaccines can help prevent variants by slowing down the rate of infection hence mutation.

Variants are caused by mutations in the virus’s genetic code. These mutations have a low chance of happening, but when a virus is given many chances by infecting a lot of people, mutations happen.

How variants develop is like playing the game of “Telephone.” The more people who repeat a message (or get infected), the more likely the message (or virus) will not stay the same from the first to the last person.

Mutations usually don’t change the way the virus works. However, on a rare occasion a mutation may make the virus better at infecting or better at avoiding the immune system. When this happens, it may be classified as a variant or subvariant. These mutated viruses are more successful at replication, so they outcompete non-mutated virus.

Vaccines prevent variants from developing by helping the body destroy the virus before it can replicate and mutate.

Once a variant has developed, vaccines help remove non-mutated forms of the virus and help the body destroy weaker forms of the virus, while mutations that make the virus better at infecting or avoiding the immune system survive. So, vaccines don’t cause variants to develop, but they make it more obvious when a variant has developed.

We are still finding and learning about the differences between different variants and how well the available vaccines protect from the new variants.