Volume 4, Issue 3, May 2016, Page: 65-72
Impact of Vaccination on Measles Transmission Patterns in Gweru City, Zimbabwe, 1960-89
Tawanda Marufu, Department of Community Medicine, University of Zimbabwe College of Health Sciences, Harare, Zimbabwe
Seter Siziya, Department of Clinical Sciences, Copperbelt University School of Medicine, Ndola, Zambia
Willard Tinago, Department of Community Medicine, University of Zimbabwe College of Health Sciences, Harare, Zimbabwe
Received: Mar. 15, 2016;       Accepted: Mar. 25, 2016;       Published: Apr. 13, 2016
DOI: 10.11648/j.ejpm.20160403.13      View  3156      Downloads  76
Abstract
A study was carried out in Gweru urban district (population-158233) in Zimbabwe to determine the impact of measles vaccine applied at 9 months of age on measles transmission patterns. A retrospective observational study that used data from measles vaccination records and measles disease surveillance was conducted. Linear regression analysis and the chi-squared test for linear trend (χ2) were used to investigate linear relationships at a 5% significance level. Vaccine coverage rates were 0% in pre-vaccination era in 1960-70 and 2-92% in 1971-89 (median=65, Q1=34, Q3=88) when they significantly linearly increased (p<0.001). In 1960-85 measles incidence rates significantly linearly increased (p<0.001) while in 1986-89 at vaccine coverage rates of >90% incidence rates significantly linearly declined (p<0.001). Proportion of vaccinated cases among measles notifications significantly linearly increased as vaccine coverage rates increased (Slope: +1.19, 95% CI [0.52, 1.86]). At vaccine coverage rates of >80% (1984-89), proportion of vaccine failures among cases aged 60-119 months was significantly higher than at vaccine coverage rates of <80% (1971-83) (p=0.011) while in age group 10-59 months proportions of vaccine failures were not different at vaccine coverage rates of <80% and >80%. In age group 60-119 months incidence rates significantly linearly increased as vaccine coverage rates increased (Slope: +29.88, 95 CI [13.95, 45.82]). In pre-vaccination era, and at vaccine coverage rates of <80% and >80% some 75% of all reported measles cases occurred by age 36-47 months, 48-59 months and 72-83 months respectively. In conclusion, measles incidence rates declined at vaccine coverage rates of >90%, while measles vaccine failures significantly increased as vaccine coverage rates increased. Increasing measles vaccination coverage led to shift of age at infection from age group <59 months to age group 60-119 months and decline in rates of measles transmission.
Keywords
Measles Vaccination, Impact, Transmission Patterns
To cite this article
Tawanda Marufu, Seter Siziya, Willard Tinago, Impact of Vaccination on Measles Transmission Patterns in Gweru City, Zimbabwe, 1960-89, European Journal of Preventive Medicine. Vol. 4, No. 3, 2016, pp. 65-72. doi: 10.11648/j.ejpm.20160403.13
Copyright
Copyright © 2016 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Reference
[1]
Goodson JL, Masresha BG, Wannemuehler K, Uzicanin A, Cochi S. Changing epidemiology of measles in Africa. J Infect Dis 2011; 204 Suppl 1: S205-14.
[2]
Moss WJ. Measles still has a devastating impact in unvaccinated populations. PLoS Med 2007; 4(1): e24.
[3]
Marufu T, Siziya S, Tshimanga M, Murugasampillay S, Mason E, Manyame B. Factors associated with measles complications in Gweru, Zimbabwe. East Afr Med J 2001; 78(3): 135-8.
[4]
ZimStat. Census 2012. Preliminary report. Zimbabwe National Statistics Agency, Harare, Zimbabwe, 2010. http://unstats.un.org/unsd/demographic/sources/census/2010_phc/Zimbabwe/ZWE_CensusPreliminary2012.pdf. Accessed 23 March 2016.
[5]
Conlan AJ, Grenfell BT. Seasonality and the persistence and invasion of measles. Proc Biol Sci 2007; 274(1614): 1133-41.
[6]
Ferrari MJ, Grenfell BT, Strebel PM. Think globally, act locally: the role of local demographics and vaccination coverage in the dynamic response of measles infection to control. Philos Trans R Soc Lond B Biol Sci 2013; 368(1623): 20120141.
[7]
Earn DJ, Rohani P, Bolker BM, Grenfell BT. A simple model for complex dynamical transitions in epidemics. Science 2000; 287(5453): 667-70.
[8]
May RM, Anderson RM. Spatial heterogeneity and the design of immunization programs. Mathematical Biosciences 1984; 72(1): 83-111.
[9]
Anderson RM, May RM. Age-related changes in the rate of disease transmission: implications for the design of vaccination programmes. J Hyg (Lond) 1985; 94(3): 365-436.
[10]
Foster SO. Measles, the ultimate challenge in urban immunization In: Universal child immunization-Reaching the urban poor, Urban Examples. New York, UNICEF, 1990.
[11]
Global Program for Vaccines of World Health Organization. Global measles strategy picks up pace. In: Summary of consultation on strategies to accelerate global measles control held on 27-28 April 1994; PAHO headquarters, Washington DC.
[12]
Center for Disease Control and Prevention. Global measles mortality, 2000-2008 MMWR Morb Mortal Wkly Rep 2009; 58(47): 1321-6.
[13]
Keeling MJ, Rhani P. Modelling infectious diseases in humans and animals. Princeton: Princeton University Press 2008.
[14]
Goldhaber-Fiebert JD, Lipsitch M, Mahal A, Zaslavsky AM, Salomon JA. Quantifying child mortality reductions related to measles vaccination. PLoS One; 2010; 5(11): e13842.
[15]
Rosenthal SR, Clements CJ. Two-dose measles vaccination schedules. Bull World Health Organ 1993; 71(3-4): 421-8.
[16]
Marufu T, Siziya S, Tshimanga M, Xaba E, Ruwodo C, Silape Z, et al. Challenges posed by changes in measles transmission patterns. Cent Afr J Med 1998; 44(1): 5-8.
[17]
Marufu T, Siziya S, Manyame B, Xaba E, Silape-Marufu Z, Zimbizi P, et al. Questioning the level of efficacy of the measles vaccine in use in Zimbabwe. Cent Afr J Med 1995; 41(8): 241-5.
[18]
Global Programme for Vaccines and Immunization. Immunization Policy. Expanded Programme on Immunization, WHO/EPI/GEN/92.3. WHO. Geneva: WHO; 1995.
[19]
Coetzee N, Hussey GD, Visser G, Barron P, Keen A. The 1992 measles epidemic in Cape Town- a changing epidemiological pattern S Afr Med J 1994; 84(3): 145-9.
[20]
De Quadros CA, Olive JM, Hersh BS, Strassburg MA, Henderson DA, Brandling-Bennett D, et al. Measles elimination in the Americas- Evolving strategies. JAMA 1996; 275 (3): 224-9.
[21]
Cutts FT, Lessler J, Metcalf CJ. Measles elimination: progress, challenges and implications for rubella control. Expert Rev Vaccines 2013; 12(8): 917-32.
[22]
World Health Organization. Meeting of the Strategic Advisory Group of Experts on Immunization, November 2012 - conclusions and recommendations. Wkly Epidemiol Rec; 88(1): 1-16.
[23]
Moss WJ, Strebel P. Biological feasibility of measles eradication. J Infect Dis 2011; 204 Suppl 1: S47-53.
[24]
De Quadros CA, Andrus JK, Danovaro-Holliday MC, Castillo-Solorzano C. Feasibility of global measles eradication after interruption of transmission in the Americas. Expert Rev Vaccines 2008; 7(3): 355-62.
[25]
Andrus JK, de Quadros CA, Solorzano CC, Periago MR, Henderson DA. Measles and rubella eradication in the Americas Vaccine 2011; 29 Suppl 4: D91-6.
[26]
Expanded Programme on Immunization. Measles control in the 1990s: Plan of action for global measles control 1992; WHO/EPI/GEN/92.3.
[27]
Cutts F. Expanded Programme on Immunization-Measles control in the 1990s: Principles for the next decade, 1990; WHO/EPI/GEN/90.2.
[28]
Marufu T, Siziya S. Impact of multiple dose measles vaccination on measles transmission patterns in Gweru, Zimbabwe. J Trop Pediatr 2001; 47(6): 335-8.
[29]
Marufu T, Siziya S, Tinago W. Comparison of single dose and multiple dose measles vaccination strategies on measles transmission patterns. European Journal of Preventive Medicine 2015; 3(3): 80-84. Doi: 10.116488/j.ejpm.20150303.18.
[30]
Khuri-Bulos NA. Measles in Jordan: a prototype of the problems with measles in developing countries. Pediatr Infect Dis J 1995; 14(1): 22-6.
[31]
Kambarami RA, Nathoo KJ, Nkrumah FK, Pirie DJ. Measles epidemic in Harare, Zimbabwe, despite high measles immunization coverage rates. Bull World Health Organ 1991; 69 (2): 213-9.
[32]
Morley D. Severe Measles. In: Paediatric Priorities in the Developing World, Butterworts 1979: 207-30.
[33]
Garnett GP. Role of herd immunity in determining the effect of vaccines against sexually transmitted disease. J Infect Dis 2005; 191 Suppl 1: S97-106.
[34]
Willingham E, Helf L. What is Herd Immunity? Available on www.pbs.org/wgbh/nova/body/herd-immunity.html [Accessed 06 December 2015].
[35]
John TJ, Samuel R. Herd immunity and herd effect: new insights and definitions. Euro J Epidemiol 2000; 16 (7): 601-6.
[36]
Anderson RM, May RM. Vaccination and herd immunity to infectious diseases. Nature 1985; 318(6044): 323-9.
[37]
Fine P, Eames K, Heymann DL. "Herd immunity": a rough guide. Clin Infect Dis 2011; 52(7): 911-6.
[38]
Fine PE. Herd immunity: history, theory, practice. Epidemiol Rev 1993; 15(2): 265-302.
[39]
Nokes DJ, Anderson RM. Measles, mumps, and rubella vaccine: what coverage to block transmission? Lancet 1988; 2(8624): 1374.
Browse journals by subject