This relates to what Geert Vanden Bossche said:
“The widespread vaccination rate is creating pressure on the virus to mutate into variants with higher levels of contagion. The unvaccinated group has been keeping the pressure down by defeating the virus and carrying natural immunity. However, as the unvaccinated population is increasingly made smaller, the pressure on the virus to mutate increases. Subsequently, these mutations stay at higher or more effective levels of infection .”
Geert Vanden Bossche Was Right, The World's Most Vaccinated Country Cancels Christmas Due to Massive Rise in COVID-19 Infections - The Last Refuge