What it prevents: Before the Hib shot was on the vaccination schedule, haemophilus influenzae type b was the number one cause of bacterial meningitis, an infection of the fluid around the brain and spinal cord, which can be fatal. This highly contagious bacterium (it can spread through coughing or sneezing) can also cause a swelling of the windpipe and pneumonia, among other deadly infections.

When it’s given: Three doses of the Hib vaccine are given: at 2 months, 4 months, and 12 to 15 months of age. Your child can receive it alone, or as part of a combination shot.

What you may have heard: While some people have claimed that there was a link between the Hib vaccine and diabetes, no study has shown any evidence to support a connection.

Risk of a reaction: About 25 percent of kids receiving the shot may have a mild reaction, such as redness, soreness or swelling at site of injection.