Haemophilus influenzae type b

Haemophilus influenzae type b (Hib) is a bacterium that can cause a number of serious illnesses, especially in young children.

Hib infections used to be a serious health problem in the UK, but the routine immunisation against Hib in 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.

What problems can it cause?

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 of the children who get Hib infections become very ill and need treatment with antibiotics in hospital.

Meningitis is the most severe illness caused by Hib and, even with treatment, one in every 20 children with Hib meningitis will die. Of those who do survive, many will have long-term problems such as hearing loss, seizures and learning disabilities.

How is Hib spread?

Hib bacteria can live in the nose and throat of healthy people and usually do not cause any symptoms.

The bacteria are usually spread in a similar way to cold and flu viruses – through the droplets of fluid in the 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 these infected droplets, or transferring them into your mouth from a contaminated surface, can allow the bacteria to spread further into your body and cause one of the infections mentioned above.

Hib vaccination

Vaccinating children against Hib has been very successful in cutting rates of Hib infections. 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 offered to babies as part of the NHS childhood vaccination programme. 

Babies have three separate doses of Hib vaccine – at two, three and four months of age – as part of the combined 5-in-1 vaccination.

A booster dose is also offered at 12-13 months as part of the combined Hib/MenC booster, to provide longer-term protection.

Read more about the NHS vaccination schedule.