University Researchers appear to have calculated the risk factor for transmission of the Covid-19 virus as 20 times higher for the unvaccinated, compared to a vaccinated person.
Your unvaccinated friend is roughly 20 times more likely to give you COVID.
An explanation of why unvaccinated people are much more likely to transmit the Covid-19 virus is given at https://theconversation.com
Another report at https://abc.net.au stated the following.
Researchers at the University of Melbourne looked at the relative risk of spreading COVID between those who have and have not been vaccinated in social settings.
It showed that not only are unvaccinated people more likely to get COVID, they’re also more likely to spread it — 20 times more likely, in fact.