Elsevier

The Lancet

Volume 359, Issue 9317, 4 May 2002, Pages 1564-1568
The Lancet

Articles
First 5 years of measles elimination in southern Africa: 1996–2000

https://doi.org/10.1016/S0140-6736(02)08517-3Get rights and content

Summary

Background

Measles is the leading cause of vaccine-preventable death in Africa. Regional measles elimination is considered feasible using current vaccines and a series of WHO-recommended strategies. We aimed to interrupt transmission of measles, and to use case-based surveillance to show the effect of such interruption.

Methods

In southern Africa from 1996, seven countries with a total population of approximately 70 million and with relatively high routine vaccination coverage implemented measles elimination strategies. In addition to routine measles immunisation at 9 months of age, these included nationwide catch-up campaigns among children aged 9 months to 14 years, then follow-up campaigns every 3–4 years among children aged 9–59 months, and the establishment of case-based measles surveillance with serological diagnostic confirmation.

Results

Nearly 24 million children aged 9 months to 14 years were vaccinated, with overall vaccination coverage of 91%. Reported clinical measles cases declined from 60 000 in 1996 to 117 laboratory-confirmed measles cases in 2000. Reported measles deaths declined from 166 in 1996 to zero in 2000. No increase in adverse events was noted after the measles vaccination campaign.

Conclusion

A reduction in measles mortality and morbidity can be achieved in very low-income countries, in countries that split their vaccination campaigns by geographical area or by age-group of the target population, and where initial routine measles vaccination coverage among infants was <90%, even when prevalance of HIV/AIDS was extremely high. Continued high-level national commitment will be crucial to implementation and maintenance of proven strategies in southern Africa.

Introduction

Measles is the most contagious disease known to man. Globally, although national immunisation programmes are estimated to prevent 80 million cases and 4·5 million deaths due to measles yearly, it is estimated that more than 30 million cases and 0·9 million deaths still occur every year.1 Approximately half of these deaths occur in Africa.2 Measles is the leading cause of death in children in Africa, even though it is preventable by a vaccine that is currently in widespread use in developing countries. The measles vaccine is highly effective and safe; the major reason for the remaining measles disease burden is failure to vaccinate, not vaccine failure.3

In 1989 and 1990, respectively, the World Health Assembly4 and the World Summit for Children5 set specific goals for the reduction in measles morbidity by 90% and of measles mortality by 95%, as major milestones towards measles eradication in the long-term. Measles elimination is considered technically feasible6, 7 because: current vaccines are sufficiently efficacious; measles is primarily a disease of man—there is no non-human reservoir; there is no carrier state and very few symptom-free cases; and measles immunity acquired by vaccination or natural disease is of very long, possibly life-long, duration.

Strategies currently recommended by WHO to achieve measles elimination include: routine vaccination coverage of 95% or more, with one dose of measles vaccine administered at 9 months of age to immunise most children; implementation of a national catch-up measles vaccination campaign in children aged 9 months to 14 years with coverage of 90% or more, to reduce the residual number of susceptible children; implementation of periodic national follow-up measles campaigns in children aged 9 months to 59 months with coverage of 90% or more, and frequency every 3–4 years depending upon the rate of accumulation of new susceptible children in the population; and the establishment of case-based measles surveillance with laboratory confirmation to monitor and assess impact.

Routine vaccination coverage with one dose of standard measles vaccine at 9 months of age is associated with a vaccine efficacy of approximately 85%.8

A mass vaccination activity lends itself better to reaching children that were not reached by the routine vaccination programme, to immunise measles susceptibles in the population. Therefore, it is more effective to provide a second opportunity for measles vaccination through a single nationwide mass measles catch-up campaign. This campaign should be done among an epidemiologically determined target group, usually children 9 months to 14 years of age regardless of vaccination or disease history.9 Experience in the WHO Americas Region shows that if catch-up campaign coverage of more than 90% can be achieved, measles transmission will be significantly reduced or interrupted.10

Unvaccinated children and children born after the measles catch-up campaign who do not respond to vaccination at 9 months of age will contribute to the gradual accumulation of measles susceptible individuals in the population. This new accumulation is then reduced with periodic mass follow-up campaigns. The timing of follow-up campaigns necessarily depends on coverage achieved during both the routine programme and the catch-up campaign. To achieve maximum effect on measles transmission, all catch-up and follow-up vaccination campaigns should be done in the low season of measles transmission, usually the drier winter months.

During the decade preceding the launching of measles elimination initiatives in the seven southern African countries of Botswana, Lesotho, Malawi, Namibia, South Africa, Swaziland, and Zimbabwe, average routine vaccination coverage with one dose of measles vaccine administered at 9 months of age of approximately 80% was achieved and sustained. This stable high routine coverage had a substantial effect on measles epidemiology.11 Measles morbidity declined substantially, the interval between epidemics lengthened, the average age of measles cases increased, the proportion of primary vaccine failures among measles cases rose, with measles mortality reduced to very low levels.

With these epidemiological pre-conditions in place, and building upon experience gained in implementing the vaccination campaigns and case-based surveillance strategies associated with the polio eradication initiative, political commitment and operational support was obtained for launching measles elimination in the seven countries, in accordance with WHO/African Regional Office recommendations, and with advocacy and technical assistance provided by the WHO Southern African Expanded Programme on Immunisation (EPI) Unit.

The national prevalence rates of HIV-1 infection in southern African countries are among the highest in the world. At present, roughly a third of fertile-age adults in southern Africa are HIV-positive, although prevalance is often much higher in certain high-risk groups such as sex workers, soldiers, and long-distance drivers. From available data, we can therefore assume that up to 10% of newborns in southern African countries become HIV infected perinatally or through breastfeeding.

Section snippets

Country information

Catch-up vaccination campaigns in each country were planned and implemented by national Ministries of Health, with technical assistance from WHO/African Regional Office. The South African government funded its measles campaign in full; in the other countries, campaigns received primary financial support from Ministries of Health, the UK Department for International Development (DFID), UNICEF, and the US Centers for Disease Control and Prevention (CDC). Particular emphasis was placed on the

Results

A total of nearly 24 million children were vaccinated during the catch-up measles campaigns. Overall, reported coverage was 91% in the seven countries that have completed their campaigns (table 1). Coverage was not independently verified. Namibia and South Africa implemented mopping-up vaccination activities in selected districts where initial coverage of less than 70% was achieved. No deaths or cases with persisting sequelae associated with vaccination were reported. In Zimbabwe, four children

Discussion

To sustain the gains achieved through the measles elimination initiative in the long-term, the seven southern African countries are continuing to implement WHO-recommended measles elimination strategies. Firstly, the Ministries of Health in the seven countries are committed to identifying and implementing innovative operational and promotional steps to raise routine vaccination coverage to more than 95% in each district, including the elimination of missed opportunities for vaccination, to

References (18)

  • BS Hersh et al.

    Review of regional measles surveillance data in the Americas, 1996–99

    Lancet

    (2000)
  • Measles - progress towards global control and regional elimination

    Wkly Epidemiol Rec

    (1999)
  • JL Christopher et al.
  • Measles mortality reduction and regional elimination. Strategic plan, 2000–2005

    (2001)
  • Measles eradication: recommendations from a meeting cosponsored by the WHO, the Pan American Health Organization and CDC

    MMWR CDC Surveill Summ

    (1997)
  • Plan of action for implementing the World Declaration on the Survival, Protection and Development of Children in the 1990s

    (1990)
  • Advances in global measles control and elimination: summary of the international meeting

    MMWR CDC Surveill Summ

    (1998)
  • Executive summary

    (1989)
  • FT Cutts et al.

    The effect of dose and strain of live attenuated measles vaccines on serological responses in young infants

    Biologicals

    (1995)
There are more references available in the full text version of this article.

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