Academic journal article Bulletin of the World Health Organization

Poliomyelitis and Measles: Vaccines and Immunization

Academic journal article Bulletin of the World Health Organization

Poliomyelitis and Measles: Vaccines and Immunization

Article excerpt

The World Conference on Poliomyelitis and Measles: Vaccines and Immunization, which was organized by the International Comparative Virology Organization (ICVO), and co-sponsored by WHO, was held on 7-12 January 1992 in New Delhi. Below are outlined the results of the major discussions held by the participants.

Poliomyelitis

Sustained progress is being made towards global poliovirus eradication. However, among the constraints likely to delay or prevent the achievement of this target are resource limitations, especially shortages of finance for the purchase of vaccine. In China and India, high immunization coverage has been attained, but there is a need for additional resources to implement essential mass campaigns in high-risk areas and for "mopping-up" activities.

An early all-out drive to eradicate poliomyelitis quickly would be far cheaper and more cost-effective than a delayed or phased approach. Such an energetic and aggressive drive to achieve the target would be facilitated by coordination of public and private sector involvement, as exemplified by the efforts of Rotary International.

In discussing delivery strategies, participants emphasized the importance of ensuring the most effective use of oral poliovirus vaccine (OPV) in the WHO-recommended strategies to achieve maximum seroconversion and also in supplementary strategies for the eradication of poliovirus. Such strategies are important for high-risk areas, such as the economically deprived slum areas of cities in developing countries.

Active surveillance for the early detection of possible cases should be undertaken, energetic control measures should be set up, and universal sustained immunization should be introduced as early in life as possible. For this purpose the case definitions used must be specific, sensitive, and appropriate to the national stage of poliomyelitis eradication.

The use of currently available poliomyelitis vaccines was discussed. It was proposed that, although WHO policies were correct in aiming for poliovirus eradication, in Africa, where access to children is limited and where health infrastructures are weak, the present OPV schedules could be supplemented with doses of inactivated virus vaccine (IPV). Also, in India the benefits of "pulse" immunization were highlighted. It was agreed that there could be a place for using IPV, especially in countries with no known wild poliovirus transmission, good surveillance systems, and where vaccine costs are not a limiting factor.

The following topics were also discussed:

-- The progress being made towards developing a more thermostable OPV.

-- The risk of continued wild virus spread, including the high risk, even in well-immunized populations, when water supplies become grossly contaminated after natural disasters.

-- The need to immunize with trivalent OPV in the neonatal period, ideally immediately after birth.

-- Developments in IPV research were outlined and also the possibility that trypsin-cleaved IPV could lead to better levels of intestinal protection than those provided by the current vaccine.

Information was presented on the types of test available for the intratypic differentiation of polioviruses, on the molecular epidemiology of wild polioviruses, and the vital contribution these processes will make to tracking the spread of viruses within and between countries. …

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