A scar that runs along the base of Dr. Lara Johnson’s neck serves as a permanent reminder of the devastating effects of a vaccine-preventable disease. When Johnson was 4 years old, she caught a dangerous, potentially deadly bacterial infection: Haemophilus influenzae type b, commonly called Hib. The bacteria attacked her epiglottis, the piece of cartilage that covers the windpipe when eating so food doesn’t get into the lungs. Her airway was closing up and she couldn’t swallow. “I had a fever