Mode matters

A proposed injectable polio vaccine may cut down the risk of contracting the paralysing disease

Published: Thursday 30 November 1995

Injectable vaccines - a better (Credit: Pradip Saha)SOMETIMES the mode of administering a vaccine into the human body may affect its efficacy considerably. This has been reinforced by American scientists working on the effectiveness of polio vaccine. According to recent reports it is being sugges ed that there should be a gradual transition from oral polio vaccine to its injectible form, to cut the risk of contracting the disease.

To provide immunity against the polio virus, two types of oral vaccines are usually administered - one using an injection that contains dead polio virus, and the other using live but weakened virus, both cultured in kidney tisues of Rhesus monkeys. This vaccine would counter polio which is characterised by symptoms that range from mild nonparalytic in *fection to an extensive paralysis of voluntary muscles.

Although injected polio vaccine is less effective than its oral counterpart, it may be less risky. It provides sufficient immunity against the virus and prevents even a ew annual cases of vaccineinduced paralysis, caused by the oral vaccine. Against this background, a panel of experts in the USA recommended recently that the injected polio vaccine should be used until "the disease is eradicated worldwide, a goal that may be achieved by AD 2000". Meanwhile, the advisory committee on inimunisation practices, of the Centre for Disease Control and Prevention ((DC) in the USA, has taken a middle position. It recommends a transitional strategy in which children would get two doses of injected vaccine, followed by two (loses of oral vaccine. This would reduce the number of vaccine-iticluced polio cases by 50 to 75 per cent, believe the proponents of the injectable vaccine.

The committee further feels that ,eventually, the country should move to the injected vaccine only". And with CDC Yet to finalise the proposed timetable for changing the immunisation regimen, physicians in the USA Will have to wait for the green signal to go for that better option.

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