Haemophilus influenzae type b (Hib)

Haemophilus influenzae (“H. flu”) are bacteria that live in people’s nose and throat and usually do not cause any harm.  Sometimes when these bacteria move to other parts of the body, they can cause infections, for example in the ear, lung (pneumonia), joint (arthritis), blood (bacteremia), or tissue covering the brain/spinal cord (meningitis).   People spread the H. influenzae bacteria to other people through respiratory droplets when they cough or sneeze.  Babies, young children, the elderly and people with certain medical conditions that affect their immune system are at increased risk of severe disease. 

A safe effective vaccine is available to prevent disease from one type of H. influenzae, type b (“Hib), and is part of the routine vaccination schedules for infants and all children under 5 years of age, as well as older children and adults with certain medical conditions.


Preventive antibiotics (chemoprophylaxis) may be recommended for contacts of Hib cases in certain situations in which unimmunized or incompletely immunized young children may have been exposed (see below).


Haemophilus influenzae
infections causing invasive disease (e.g., pneumonia, bacteremia, meningitis, epiglottitis, septic arthritis, cellulitis, pericarditis, or osteomyelitis) in children under 5 years of age are reportable in Orange County within one (1) working day of identification.  To report a case, health care providers/facilities should call OCHCA Epidemiology at 714-834-8180 or fax records to 714-560-4050.  

Healthcare Professionals

For more information, see the Centers for Disease Control (CDC) website https://www.cdc.gov/hi-disease/index.html.

Last reviewed December 27, 2018