Shielding advice

I can absolutely understand your worry! We’ve been shielding since March last year, and were so relieved when schools were all online! Sadly our 17-y-o is back in class now, but at least Mr R and I have both had our first COVID vaccinations. 
In terms of your stepson, you and your husband will have to decide where the level of acceptable risk is for you. For me, going and visiting other people or staying with them would be an absolute no-no. If he’s taking proper precautions at work (mask, distance etc) then it difficult to avoid that situation and he’s doing what he can to reduce the risk there, but socialising with others is where it increases. It’s hard to tell someone they’re not allowed to socialise - but on the other hand that’s how CEV people have been living for a year now so... 

All that said, you were told that the Avastin doesn’t affect immunity and presumably it’s a while since your chemo finished so it will have improved, and you’ve had the first jab, so your risk of serious illness is reduced...

it’s not an easy decision at all, and I don’t envy you having to make it. Our daughter at university wants to come home for a few days, so we’re having to go through a similar calculation of risk. 
so no advice from me. Just sympathy. I hope you manage to work something out which everyone can agree to and be ok with x

Thank you for the perspective. I think you’re absolutely right - it’s not so much going out to work, it’s the feeling that we would be opening our house by extension to more than just him. We’ve had a chat and given him the choice of moving in but following regulations (eg no staying over at gf) or sofa surfing with his mum until regulations relax and we’re more comfortable with the risks. Horrid situation, but no worse than many others are living with x

I’m glad you were able to talk to him and lay out your concerns and expectations in advance so that everyone’s making an informed decision about the effect ans consequences of each option. I hope all goes well x