Herd immunity means it’s effectively eradicated, meaning that enough people are protected from it that the virus cannot readily find new hosts and basically “dies out” in the areas in which herd immunity is reached. That’s why severely immunocompromised people, eho often cannot get vaccines or cannot mount a response even if they do get vaccines, do not get, e.g., polio. If only the majority didn’t get the virus, those who are susceptible (the minority) still would, but this doesn’t really happen (in places where herd immunity is reached). Other places around the world may still have the virus floating around, but after a while at the herd immunity level in a location/ country, it is effectively eradicated.

It’s correct how it is. It’s acting as an adjective, as if you said “red shelter.” “Migrant’s shelter” would mean the shelter belongs to one migrant. “Migrants’ shelter” would mean the shelter belongs to a group of migrants, which is also incorrect because they do not own it. Hope this helps :)

40c is 104f. The article mentions possibly peaking at 48c, which is 118f. In case anyone thought something was a little off