Small dose, needle-less polio vaccines on horizon

A very small dose, needle-free polio inoculations to immunise infants from the incapacitaing viral disease may be in the offing.

Immunisation against paralytic polio disease is practised  as one of key aspect of universal immunisation programmes across the world as part of eradicating polio from the world.

Polio disease is still a problem in many developing countries and currently, the polio vaccination is done in phases involving multiple doses.

A new research, however, indicate that the polio vaccine can be administered in very small doses and that too without using the conventional needle pricks with greater efficacy.

One fifth of the usually administered dose of polio vaccine could protect babies against the polio virus nearly as well as a full dose.

The low dose vaccine can be administered directly under the skin using a specially designed needle-free syringe.

A study using low-dose vaccine conducted in infants showed that more than 95 percent of the infants mounted an effective immune response against polio when injected just beneath the skin, using a needle-free jet injector made by Bioject Medical Technologies.

Bioject Medical Technologies Inc., based in Portland, Oregon, is an innovative developer and manufacturer of needle-free injection therapy systems (NFITS).

NFITS provide an empowering technology and works by forcing medication at high speed through a tiny orifice held against the skin. This creates a fine stream of high-pressure fluid penetrating the skin and depositing medication in the tissue beneath.

The injectable polio vaccine costs about $3 per dose while the much more prefereed oral polio vaccine is far cheaper. But the oral version of the polio vaccine contains a weakened form of polio causing virus which could turn a mutan strain and cause polio diseases in some cases.

Therefore, the new research could considerably bring down the cost of immunization, which is imposing a great financial burden in the developing and the least developed countries.

“If we can do one-fifth the dose, we can at least get it down to one dollar, so we are getting into the neighborhood of a price that may be affordable for developing countries in the future,” stated Dr. Roland Sutter of the World Health Organization.

Polio is still a nagging health problem in countries such as Afghanistan, India, Pakistan and Nigeria.

India continues to be among the only remaining five reservoir of polio virus in the world, despite decades of intensive preventive programmes against the disease. Of the total 1,315 cases of poliomyelitis reported worldwide in the year 2007, over 60% of cases (874) occurred in India.

Most recently two more new cases were reported both WPV3 cases from Moradabad, Uttar Pradesh (UP). However, the total number of polio cases for 2009 have come down to 21, so far, compared to 165 cases at this time last year.

The World Health Organization has a budget of $2.6 billion for its polio eradication efforts in 2010-2012, but is

still in about half of the required funds for that period.

Poliomyelitis (polio) is a highly infectious disease caused by a virus. It affects the nervous system, and can cause total paralysis in a matter of hours. It can strike at any age, but affects mainly children under three (over 50% of all cases).

The virus enters the body through the mouth and multiplies in the intestine. Initial symptoms are fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs. One in 200 infections leads to irreversible paralysis (usually in the legs).

Amongst those paralysed, 5%-10% die when their breathing muscles become immobilized. Although polio paralysis is the most visible sign of polio infection, fewer than 1% of polio infections ever result in paralysis.

Poliovirus can spread widely before cases of paralysis are seen.  After initial infection with poliovirus, the virus is shed intermittently in faeces (excrement) for several weeks. During that time, polio can spread rapidly through the community.

In the remaining polio endemic countries, poliovirus is mainly passed through person-to-person contact. Most people infected with the poliovirus do not develop polio paralysis or other symptoms of polio infection. However one in 200 people do have symptoms and can become paralyzed.

The virus enters the environment through faeces of people infected then is passed to others especially in situations of poor hygiene.

The poliovirus can also infect persons who have been vaccinated and can be carried by them. Such individuals will not develop polio, but can carry the virus in their intestines and can pass it to others in conditions of sub-standard hygiene. The disease may infect thousands of people, depending on the level of sanitation, before the first case of polio paralysis emerges.

Individuals can carry the virus in their intestines just long enough to transmit to others.

WHO considers a single confirmed case of polio paralysis to be evidence of an epidemic – particularly in countries where very few cases occur.

Once established in the intestines, poliovirus can enter the blood stream and invade the central nervous system – spreading along nerve fibres. As it multiplies, the virus destroys nerve cells (motor neurons) which activate muscles.

These nerve cells cannot be regenerated and the affected muscles no longer function. The muscles of the legs are affected more often than the arm muscles. The limb becomes floppy and lifeless – a condition known as acute flaccid paralysis (AFP).
More extensive paralysis, involving the trunk and muscles of the thorax and abdomen, can result in quadriplegia. In the most severe cases (bulbar polio), poliovirus attacks the motor neurons of the brain stem – reducing breathing capacity and causing difficulty in swallowing and speaking. Without respiratory support, bulbar polio can result in death.