"My mother is currently undergoing chemotherapy for stage 3 cancer. She cannot get the vaccine because her immune system cannot handle both that and chemo at the same time. I got the vaccine more for her than for me, since I am young and healthy and more likely to win the lottery than to die from COVID. So to answer your question you are endangering any immunocompromised people you might be in contact with."
My understanding the Vaccine will not prevent all people from catching Covid-19. The vaccine lowers the risk factor for severe illness.
Are you really protecting your mother if you could still catch Covid-19 after having the Vaccine? "Keep in mind that if you’re fully vaccinated from COVID-19, your risk of getting COVID-19 might be low. But if you become infected, you might spread the COVID-19 virus to others even if you don’t have any signs or symptoms of COVID-19."
From Mayo Clinic My wife is at stage 4 and cannot have the vaccine too. I will not take the vaccine and just avoid the public for now. I do not want to get infected and not know it. I prefer to feel the symptoms so I can self isolate.