2 weeks i believe for anyone infected to pass symptoms and you can get it more than once. But then my mum has never had it and been around it many times. Your call at the end of the day. Pregnant women can suffer more with it and it can be serious. So personally I'd just say no. As a mother she should understand
My understanding was that once all the spots have scabbed, they’re no longer contagious. So I’d have thought your nephew wouldn’t be contagious anymore. But I’m not medically trained.
Nah do what you think is best. There will be many other birthdays and get together make sure you do what is best for you to put your mind at ease
I would politely ask them not to come - if she’s a responsible parent and a normal human being she will understand You do not need anymore drama right now!! It will probably be fine, but why take the risk?!!
I work in a nursery which had an outbreak when I was third trimester. My midwife checked my antibodies and I had them so baby and I were fine. However she did caution me about my 2 yr old catching it incase she had it when baby came. As it can be more high risk if newborns catch it It can take up to 21days from contact with pox for a child to show signs after being infected. I’d think you have every right not to invite them if your worried and I think your sister should be more understanding x