If your supervisor is still insistent, you might want to speak with your HR and see if theres special concession for being pregnant and not working in the front line. Anyway I've been on front line service doing temperature checks and close contact with hundreds of strangers on a daily basis while being pregnant so it's really not much of an issue but then again it's up to individual comfort level.
I think you can talk to your manager that you are pregnant i.e. considered to be in the vulnerable group and ask to be excluded for this duty.
Anonymous