Haemophilus influenzae type b (Hib) is a bacterium that can cause a number of serious illnesses, particularly in young children.
Hib infections used to be a serious health problem in the UK, but the routine immunisation against Hib, given to infants since 1992, means these infections are now rare.
Of the small number of cases that do occur nowadays, most affect adults with long-term (chronic) underlying medical conditions, rather than young children.
Problems caused by Hib
Hib bacteria can cause several serious infections, including:
- meningitis – infection of the lining of the brain and spinal cord
- septicaemia – blood poisoning
- pneumonia – infection of the lungs
- pericarditis – infection of the lining surrounding the heart
- epiglottitis – infection of the epiglottis, the flap that covers the entrance to your windpipe
- septic arthritis – infection of the joints
- cellulitis – infection of the skin and underlying tissues
- osteomyelitis – infection of the bones
Many children who develop Hib infections become very ill and need treatment with antibiotics in hospital.
Meningitis is the most severe illness caused by Hib. Even with treatment, 1 in every 20 children with Hib meningitis will die.
Those who survive may have long-term problems, such as hearing loss, seizures and learning disabilities.
How Hib is spread
Hib bacteria can live in the nose and throat of healthy people, and usually don't cause any symptoms.
The bacteria are usually spread in a similar way to cold and flu viruses, through infected droplets of fluid in coughs and sneezes.
The bacteria can be spread by healthy people who carry the bacteria, as well as those who are ill with a Hib infection.
Inhaling the infected droplets or transferring them into your mouth from a contaminated surface can allow the bacteria to spread further into your body, causing one of the infections mentioned above.
Immunising children against Hib has been very effective in cutting rates of Hib infections. Before a vaccine was available, Hib infection was the main cause of meningitis in young children in the UK. Now, it's much rarer.
From more than 800 confirmed cases a year in England in the early 1990s, the number of Hib infections has now fallen to fewer than 20 cases a year.
The Hib vaccine is routinely offered to babies as part of the NHS childhood immunisation programme.
Babies have 3 separate doses of Hib vaccine – at 8, 12 and 16 weeks of age – as part of the combined 6-in-1 vaccine. Babies receive a booster dose of the Hib vaccine between 12 and 13 months of age as part of the combined Hib/MenC vaccine. This provides longer-term protection against Hib and helps protect against Meningococcal C (MenC) infections.