Polio Is Making a Comeback in the U.S. Here’s Why.

WSJ
1 年前
The U.S. was recently added to a list of roughly 30 countries where vaccine-derived polio is circulating. WSJ’s Daniela Hernandez explains what vaccine-derived polio is, how this strain made it to the U.S. and how public-health officials are responding. Photo illustration: Adele Morgan