When VACCINATED FOR THE DISEASE you are UNLIKELY to catch it, but if exposed, YOU CAN STILL CATCH IT

When NOT VACCINATED FOR THE DISEASE you are LIKELY to catch it, and if exposed YOU WILL LIKELY CATCH IT

When UNVACCINATED PEOPLE who CATCH THE DISEASE are in general public, EVERYONE CAN STILL CATCH IT, EVEN THOSE WHO ARE VACCINATED

When you are unvaccinated against the disease, you are MORE LIKELY TO CATCH THE DISEASE, and THEREFORE MORE LIKELY TO SPREAD THE DISEASE

The point of widespread vaccination is to PREVENT PEOPLE FROM CATCHING IT, which PREVENTS PEOPLE FROM SPREADING IT

I don't know how much simpler I can make this, this concept has literally been around for over 200 years