in some large countries such as the US if they have received the vaccine they are allowed to remove the mask.
I was a little surprised to read this news. I think the policy cannot be applied in all countries. do vaccines really make someone immune?

Vaccines prevent disease 95% of the time (the case with Pfizer and Moderna vaccines), but 5% risk remains. But that doesn't mean that it will be OK to remove the mask. Because people without mask can propagate the virus, to those who are not vaccinated (remember that those who are aged below 16 years are yet to be given an opportunity to get the vaccine in the United States). It is upto the government to decide whether those who are vaccinated are given a right to be without their masks.