People get vaccinated for measles before they're even done with elementary school. It would be preposterous to assume that this would cause some sort of outbreak.
The most likely reason they would come here is because of poverty. The U.S. is known as a free, safe place where anyone can have a chance at something great, and people are trying to take that away.
The Mayflower brought those. Thinking immigrants are the bad guys when WE'RE the original ones who brought diseases, invaders, and terrorists to America, murdering countless Native Americans. Biden is just helping people escape drug cartels and poverty.