Polio vaccination--a review of strategies

Global public health mandates in a diverse world: the polio eradication initiative and the expanded programme on immunization in sub-Saharan Africa and South Asia

BACKGROUND

The circulation of wild poliovirus is expected to cease soon due to the success of the global polio eradication initiative. Thereafter, intensified polio eradication efforts such as National Immunisation Days (NIDs) will most likely be discontinued. As a consequence, the expanded programme on immunization (EPI) will no longer enjoy extra inputs from the polio eradication initiative. We investigated whether today's EPIs are ensuring universal and equitable vaccine coverage; and whether the removal of extra inputs associated with the implementation of NIDs is likely to affect EPI coverage and equity.

METHODS

Using data from Demographic and Health Surveys conducted in 15 countries of South Asia and Africa during 1990-2001, we examined absolute levels of EPI coverage; changes in EPI coverage after the introduction of NIDs; and relative coverage according to urban versus rural residence, higher versus lower education of mothers, and wealthiest vs. poorest population segment.

RESULTS

Polio and non-polio antigen coverage increased in seven countries during the study period. Substantial inequalities in coverage of non-polio antigens persist, however, translating into inequities in the risk of contracting vaccine preventable diseases. In some African countries, routine EPI coverage and/or equity declined during the study period. In these countries, any positive effect of NIDs on the EPI coverage must have been small, relative to the negative effects of declining economies or deteriorating health systems. In Nigeria, Zimbabwe, Kenya and Malawi, even polio coverage declined, in spite of the introduction of NIDs.

CONCLUSION

As additional inputs associated with polio eradication will cease, routine EPI services need to be strengthened substantially in order to maintain levels of population immunity against polio and to improve social equity in the coverage of non-polio EPI antigens. Our findings imply that this aim will require additional inputs, particularly in African countries.

The use of mass campaigns in the expanded program on immunization: a review of reported advantages and disadvantages

The use of mass immunization campaigns (MICs) has been and remains controversial. To evaluate these campaigns, the authors review the literature relating to their effectiveness, sustainability, and cost-effectiveness in controlling diseases and raising immunization coverage levels, and their impact on the subsequent development of routine immunization services. Well-conducted campaigns have increased vaccine coverage levels and decreased disease morbidity and mortality. Their use in the Americas has been associated with the apparent elimination of poliomyelitis. However, unless health care infrastructure is improved, or campaigns are repeated, gains in coverage levels may not be sustained. Studies suggest that MICs are often not as cost-effective for raising coverage as the delivery of vaccines through routine services, but the use of coverage as the only outcome measure is questionable. Mass immunization campaigns can increase awareness of vaccination and may be appropriate in situations where new programs are to be initiated, in refugee situations where people congregate into areas with little infrastructure, and in disease eradication efforts when specific time goals are set. Little information is available on whether MICs strengthen or interfere with the development of routine services. To be successful, MICs require a well-coordinated and planned effort on the part of national authorities with the identification of specific goals, intensive social promotion, and strong management. In addition, research is needed to clarify how MICs should be evaluated.

Poliomyelitis: eradication in sight

Great strides have been made towards the control of poliomyelitis since the introduction of the two poliovaccines – inactivated poliovirus vaccine (IPV), which was licensed in the United States in 1954, and live attenuated oral poliovaccine (OPV), in 1961. Today a large majority of physicians and other health–care workers in industrialized countries never see a patient with paralytic poliomyelitis. Unfortunately, this is far from the situation in many developing countries, particularly in tropical and subtropical climates, where hundreds of thousands of children still become paralysed victims, year in and year out.

Vaccination strategies in developing countries

By 1990 it is hoped that all of the world's infants will have access to immunization services and that these services will then continue indefinitely. The link between people and health services, including immunization, can only be forged and maintained by an effective system of delivery and support to all health workers. A careful choice of strategies for this delivery system and an understanding of local cultural attitudes and behaviour is vital if this link is to be effective. Health workers will have to be trained and then supported in the field by regular contact with their supervisors. They will also need continuous, reliable, predictable and adequate supplies of equipment, drugs, vaccines, fuel and money, including salaries. Immunization is cost effective as a health intervention, but an effective programme of immunization can contribute much more than just vaccines, if it is developed in the context of primary health care (PHC) as originally proposed in 1978 at the conference in Alma Ata.

Well child clinics and mass vaccination campaigns: an evaluation of strategies for improving the coverage of primary health care in a developing country

Millions of children in developing countries are dying from diseases that could be prevented or treated by simple interventions. To examine ways to improve the delivery of these basic services, we evaluated well child clinics and mass vaccination campaigns under operational conditions in a rural area of Nicaragua. We found that mass vaccination campaigns using volunteers reached 77.1 per cent of the population under age six. At stationary well child clinics in which villages were invited to a health center and a small food ration was used as an incentive, attendance improved to 94.1 per cent. Similar attendance levels (99.2 per cent) were attained by mobile well child clinics also using a food incentive. Attendance at stationary clinics decreased with the distance of the village from the health center. However, stationary clinics took up only half as much health workers' time as mobile clinics. Our results suggest that stationary clinics employing food as an incentive could be used for villages or neighborhoods close to a health center while mobile clinics offering food should be reserved for more isolated villages.