In other words, a so-called "leaky vaccine" or a vaccine that lowers the chances of severe illness, but still allows for transmission of a virus, can create conditions that promote the evolution of more virulent pathogens.
For further reading here is a 2015 NIH-funded study that found "imperfect vaccination can enhance the transmission of highly virulent pathogens.". https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4516275/
The chart entitled "genomic epidemiology of novel coronavirus" shows the increase in mutations after the introduction of these leaky vaccines at the beginning of the year.
for fun, re-frame the debate into their own ideology.
ask, do you believe in science?
do you believe in man-made climate change?
do you believe in human over-population?
do you believe in evolution?
do you believe in survival of the fittest?
do you believe that vaccines are allowing too many of the un-fit to survive, and cause human over-population, and therefore man-made climate change?
wouldn't it be better to let the un-fit die young, before they pass their un-fit genes onto the next generation?