Elsevier

Vaccine

Volume 30, Issue 9, 21 February 2012, Pages 1594-1600
Vaccine

Measles control in Sub-Saharan Africa: South Africa as a case study

https://doi.org/10.1016/j.vaccine.2011.12.123Get rights and content

Abstract

Background

Due to intensified measles immunization efforts, measles mortality has decreased substantially worldwide, particularly in Sub-Saharan Africa (SSA). The World Health Organization (WHO) estimated a 92% decrease in measles-related deaths in the WHO AFRO region for the period 2000–2008. Recently, the AFRO region established a measles pre-elimination goal and experts have suggested engaging in a measles eradication campaign at the global level. However, recent large-scale outbreaks in many Sub-Saharan African countries present a challenge to measles control efforts. This paper examines measles immunization and the impact of measles supplemental immunization activities (SIAs) on routine immunization coverage in South Africa (SA).

Methods

We reported on immunization coverage trends in SA for the period 2001–2010 at the province and district levels. The data included routine immunization for 1st and 2nd doses of measles vaccine (MCV1, MCV2), SIAs, 1st dose of Bacille Calmette-Guérin vaccine, 1st and 3rd doses of oral polio vaccine (OPV1, OPV3), 3rd dose of Diphtheria–Tetanus–Pertussis–Haemophilus-influenzae-B vaccine (DTP-Hib3), and the number of under-one-year-olds having completed a primary course of immunization (Imm1). A regression model looked at the SIA impact on routine coverage.

Results

Over the past decade, MCV1 and MCV2 coverage have increased nationally from 68% and 57% in 2001 to 95% and 83% in 2010, respectively. SIA coverage has remained at high levels, around 90%, over the same period. Substantial heterogeneity in MCV1 and MCV2 coverage is present across SA districts, with differences in coverage of 56% (MCV1) and 51% (MCV2) in 2010. In any given year, occurrence of SIAs was associated with a decrease in routine immunization coverage of MCV1, MCV2, OPV1, OPV3, DTP-Hib3, and Imm1, at the district level.

Conclusions

The heterogeneity in measles vaccination coverage across SA districts challenges the goal of measles elimination in SA and SSA. The reduction in routine immunization coverage associated with the occurrence of SIAs raises the legitimate concern that SIAs may negatively impact health systems’ functioning.

Highlights

Measles vaccine (MCV) coverage presents great heterogeneity across SA districts. ► MCV coverage heterogeneity challenges measles elimination in Sub-Saharan Africa. ► Measles mass campaigns were associated with decrease in routine clinic activities. ► Measles mass campaigns may negatively impact health systems’ functioning.

Introduction

The burden of disease attributed to measles throughout history is considerable. Before the introduction of a live attenuated measles vaccine in 1963, measles was an unavoidable risk in early life [1]. Prior to the 1960s, 135 million cases and 7–8 million deaths were assumed to occur each year globally [2]. In 2000, measles-related deaths accounted for 1–5% of under-five deaths worldwide [3], [4], [5], [6].

Responding to the momentum of the Millennium Development Goal 4 (MDG 4), the World Health Assembly (WHA) in 2003 adopted a resolution to reduce deaths attributable to measles by 50% from 1999 levels, by 2005 [7]. Shortly thereafter, UNICEF and the World Health Organization (WHO), in defining a Global Immunization Vision and Strategy (GIVS) for 2006–2015 [8], set the goal to further reduce measles-related deaths by 90% from 2000 levels, by 2010, which was officially endorsed by the WHA in 2005. Drawing on the WHO's Expanded Programme on Immunization (EPI) [9], the UNICEF's Universal Childhood Immunization by 1990 Initiative (UCI) [10], and with the benefit of momentum developed by the Global Alliance for Vaccines and Immunization (GAVI) [11], the Measles Initiative [12] has emerged. The Measles Initiative is a consortium of global health agencies which provides support to measles-burdened countries in order to achieve the measles-mortality reduction goal. The focus has been on sustaining high coverage of routine immunization of children at around 9 months and to supplement it with a recommended second dose [13]. In high-income nations, the second dose is included in the routine vaccination schedule and usually administered to children before school entry [13]. In low- and middle-income countries, a second dose of measles vaccine is offered through supplemental immunization activities (SIAs) [13]. During SIAs, children are targeted for vaccination regardless of their previous history of measles vaccination. This approach, implemented by the Pan American Health Organization (PAHO) since the 1990s, is thought to have contributed to the elimination of the endemic transmission of measles in the Americas [14].

The same strategy has been exported and adapted to Sub-Saharan Africa and may explain the reported drop in measles deaths and incidence in Africa in the last decade [15], [16], [17]. WHO researchers have reported achievement of the 2005 measles mortality reduction goal [18] as well as continued downward trends in worldwide measles mortality toward the 2010 measles mortality reduction target [19]. The Africa WHO (AFRO) region saw a 92% decrease in measles-related deaths from 2000 to 2008, with an estimated 28,000 deaths attributable to measles in the AFRO region in 2008 [19]. Most recently, the AFRO region measles technical advisory group has recommended establishing a pre-elimination goal by the end of 2012 [20], [21]. Experts at the global level have even been considering the feasibility of engaging in measles eradication [22], [23]. However, 28 out of the 46 AFRO countries reported laboratory-confirmed measles outbreaks in 2009–2010 [24]. These outbreaks present challenges to the recent successes against measles-mortality and to the goal of measles elimination in the AFRO region.

In South Africa (SA), a first and a second dose of measles vaccine are given to children at 9 and 18 months. Since 1996, SA has been at the forefront of implementing regular national or subnational SIAs [25], [26]. These SIAs are executed in each of the country's nine provinces and fifty-two districts. However, a measles outbreak which started in Gauteng province in 2009 spread to the whole country in 2010 [27], an example of one of the outbreaks which challenge measles mortality reduction goals and even basic measles control.

The analysis presented here is intended to inform the measles control policies of Sub-Saharan African countries by using SA as a case study. We analyzed coverage levels of the first and second doses of measles routine vaccination, and supplemental immunization activities for the period 2001–2010 at both the district and province levels in SA. We also analyzed the association between the implementation of a supplementary immunization campaign and its impact on the coverage of routine immunization services in a given year. This analysis will assist policy makers in evaluating how best to fill gaps in coverage in order to achieve successful measles control in SA, and elsewhere in Sub-Saharan Africa.

Section snippets

Data

We used district-level routine immunization data for the years 2001–2010 sourced from the District Health Information System (DHIS), SA. This included coverage data for the first and second doses of measles vaccine (MCV1, MCV2). We also had routine immunization coverage data for the 1st dose of Bacille Calmette-Guérin vaccine (BCG), the 1st and 3rd doses of oral polio vaccine (OPV1, OPV3), the 3rd dose of Diphtheria–Tetanus–Pertussis–Haemophilus-influenzae-B vaccine (DTP-Hib3), and the number

Results

The trend in coverage over the last decade for MCV1 and MCV2 implemented by routine immunization services at the province level, and for SIAs at the national level, is plotted in Fig. 1.

Fig. 1 shows that, nationally, coverage of MCV1 and MCV2 have increased by 27% and 26% from 68% and 57% in 2001 to 95% and 83% in 2010, respectively. Comparatively, SIA coverage (Fig. 1) has remained at high levels, around 90%, over the years 1996–2010. In 2010, SIA coverage reached about 92% of children aged

Discussion

This analysis provides evidence of the trends in measles immunization coverage in SA for routine and supplemental immunizations over the last decade at province and district levels. It points to the successes that have been achieved in scaling up immunization coverage but also highlights the challenges facing the country's effort toward the control and elimination of measles. The coverage estimates are consistent with prior estimates [30], [31], [32], [33]. For the period 2001–2010, coverage of

Conclusions

High national rates of measles vaccination coverage can mask the important underlying sub-national heterogeneity/inequality seen in districts presenting low rates of immunization coverage. This situation prevents effective disease control, which in turn affects potential for disease elimination. In the case of measles, SIAs can reduce some of this heterogeneity while raising overall coverage in all districts, and addressing the promise of equity in targeting those not reached by health care

Acknowledgements

The study was funded by the Bill & Melinda Gates Foundation through the Disease Control Priorities Network (DCPN) Project grant to the Department of Global Health at the University of Washington. The study was undertaken under the auspices of PRICELESS SA (Priority Cost Effective Lessons for Systems Strengthening – South Africa). The authors wish to thank Meg Stalcup and two anonymous reviewers for providing valuable comments on the manuscript.

This work would not have been accomplished without

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