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
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.
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
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