There is no evidence that immigration spreads disease. One recent study in The Lancet found that immigration makes arrival countries healthier. Another review of European studies found that the “risk of transmission” of diseases from refugees and asylum seekers to local populations “is very low”—in fact, that what little risk exists is borne almost entirely by the refugees themselves, on account of being forced to live in squalid conditions.

It doesn’t even make sense as a claim. Tens of millions of people visit the United States every year from all over the world, not counting the U.S. citizens who travel or live abroad. Air, ocean currents, mosquitoes, and migrating animals don’t pass through customs. Even at using the most exaggerated administration estimates, the hundreds of thousands of people trying to cross the U.S.-Mexico border aren’t even a statistical drop in the bucket. It is literally xenophobia: an irrational fear of foreigners.

—Jonathan M. Katz, in “Immigrants aren’t deadly. Fox News’ lies are.”