A sure shot

摘要

The existing vaccine for tuberculosis is a gamble-sometimes it works, sometimes it doesn't. But now, in a breakthrough that could save millions of lives, immunologists have figured out why it is so hit or miss, and how to fix the problem. TB is caused by a bacterium that spreads through the air and infects the lungs. Not everyone who is infected gets sick, but the disease is so prevalent in regions like Africa that it's responsible for a quarter of preventable adult deaths. You can treat the infections, but more and more resist standard drugs, so a better vaccine is sorely needed.