From my understanding, even after being vaccinated, you can still catch the virus and transmit the virus.
The vaccine isn’t 100%, and therefore you can still catch it.
Also, you can still ‘shed’ the virus for a time after being vaccinated.
You can’t however catch the virus from the vaccine. Vaccines don’t work like that. You can however experience some symptoms from the vaccinations but that’s rare and it’s all vaccines have the potential of causing people allergic reactions.
The take away though is that you’re better protected from catching and/or transmitting the virus even after the first dose.
So, get it. Increase your chances of being protected and protecting your loved ones and anyone you come into contact with.
Hope that makes it a little clearer.