HIB VACCINE : Why it should be included in the immunisation schedule?

Dr. Rohit C. Agarwal

Hon. Secretary General, IAP; Consultant Pediatrician, Hira Nandani Hospital, Mumbai

 

 

Haemophilus influenzae type B, or Hib, is a bacterium estimated

to be responsible for some three million serious illnesses and an

estimated 386,000 deaths per year, chiefly through meningitis

and pneumonia. Almost all victims are children under the age of

five, with those between four and 18 months of age especially

vulnerable. In developing countries, where the vast majority of Hib

deaths occur, pneumonia accounts for a larger number of deaths

than meningitis. However, Hib meningitis is also a serious problem

in such countries with mortality rates several times higher than

seen in developed countries; it leaves 15 to 35% of survivors with

permanent disabilities such as mental retardation or deafness.

Contrary to what the name Haemophilus influenzae suggests, the

bacterium does not cause influenza.

Hib is commonly found in the noses and throats of healthy

individuals living in regions where vaccination is not carried out.

Almost all unvaccinated children are exposed to Hib by age five.

The bacterium is spread by exhaled droplets. Occasionally, Hib

can invade the bloodstream and cause infection and disease

in other parts of the body, including the meninges leading to

meningitis, and the lungs, causing pneumonia. Unlike measles,

polio or diphtheria, Hib does not cause a specific illness with

which it, alone, can be identified. The most deadly forms of Hib

infection include pneumonia and meningitis, but those diseases

can have other causes, and can look the same whether caused by

Hib or some other agent. More rarely, Hib is responsible for other

life-threatening complications in young children, such as septic

arthritis, an inflammation of the joints, and septicaemia, both of

which also can have other causes. And it may lead to epiglottitis.

Hib is preventable - highly effective vaccines have been available

 

since the early 1990s. Yet hundreds of thousands of children die year

after year from Hib disease. The two major obstacles to prevention

of Hib disease are a shortage of information and a shortage of

money. The information shortage is largely due to the difficulty of

diagnosing Hib disease - it claims most of its victims without ever

being recognized. In addition, Hib vaccine is more expensive than

classic childhood vaccines - at the price offered to the world’s lower

income nations in 2005, it costs roughly seven times the total cost

of vaccines against measles, polio, tuberculosis, diphtheria, tetanus,

and pertussis. Those two factors put many developing countries in

a difficult situation. They want evidence of the extent and damage

done by Hib before deciding whether to add a more costly vaccine

to their infant immunization programmes. Developing countries

may also need external funding assistance if they decide to provide

vaccination against Hib.

89 countries offered infant immunization against Hib by the

end of 2004, with two of those countries providing it in parts of

their territories. 92% of the populations of developed countries

was vaccinated against Hib as of 2003. The vaccination coverage

was 42% for developing countries, and 8% for least-developed

countries. Hib conjugate vaccines, given by intramuscular

injection, are highly effective and have almost no side effects.

Three doses are usually administered in infancy, starting at around

age six weeks. In some countries, a booster dose is also offered

between 12 & 18 months of age. The Global Immunization Vision

and Strategy (GIVS), developed by WHO, UNICEF, and partners, has

among its aims “strengthening the current immunization system

so that it can maximally deliver currently available vaccines as well

as under-utilized vaccines,” including Hib.