The odds of this are far less than the odds of me killing my wife by taking a drive with her. In the same way that I can live with the risk of driving a car with her in it, I can live with this risk. Of course if that actually happened I would feel terrible, in both cases. But life is about weighing risks, and for now I'm comfortable with the risk of remaining unvaccinated.
No, I don't wear masks. That's a different ethical discussion. I don't feel or accept a moral burden for potentially spreading a virus in any case. I wouldn't walk about while sick of course, or have uninformed sex if I had an STD, but if I'm asymptomatic and end up accidentally giving someone an illness in the course of normal life, sorry, but that's just life. People who spread the flu accidentally are not immoral people, whether they get the flu shot or not. Likewise here.