Please stop spreading misinformation. I recommend that everyone get vaccinated if they can, but the vaccines have only a limited and temporary effect in reducing transmission.

https://www.nature.com/articles/d41586-021-02689-y

The reality is that those grandparents are going to be exposed to the virus regardless of what their grandchildren do. Those grandparents have had plenty of time to get vaccinated themselves.

https://www.businessinsider.com/delta-variant-made-herd-immu...