Children's Vaccines Health Center

Hib Outbreak Kills Unvaccinated Child

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There's supposed to be a booster shot at 12-18 months for either vaccine, but the CDC has asked parents to hold off on that shot until the shortage is over (unless their child is at high risk of Hib illness).

Children who have not had their Hib shots and who are at least 1 year old need only one Hib shot, Schuchat says.

Why is there a Hib outbreak now? Minnesota data suggest that the Hib vaccine shortage is playing a role. A quick study shows that 18% of 7-month-old Minnesota kids who got other vaccines did not complete their primary Hib vaccination.

"We interpret this as a shortage of vaccine. Providers did not have the vaccine in their offices," Minnesota state epidemiologist Ruth Lynfield, MD, said at the news conference.

That has probably created a pool of children vulnerable to Hib infections. Before the shortage, widespread Hib vaccination kept infection rates low enough to protect even unvaccinated kids -- a phenomenon called "herd immunity."

But now that protection has ebbed below the level needed to maintain herd immunity, unvaccinated kids pose a threat to kids whose age or immune status make them extremely vulnerable to serious Hib complications.

And Hib can be quite serious. The bug's name, Haemophilus influenza, is confusing. In the days before viruses were discovered, it was thought to be the cause of flu. That's not true. But Hib bacteria can cause pneumonia, severe upper airway infection, and meningitis. Even if not fatal, Hib meningitis can leave children deaf or with severe brain or nerve damage.