Impact of Supplementary Immunization Activities in Measles-Endemic Areas: A Case Study From Guangxi, China

Abstract

Because of limited resources, each year during the period from 1999 through 2007, only about one-quarter of the 111 counties in Guangxi province were selected by means of risk assessment to participate in Supplementary Immunization Activities (SIAs), targeting children aged 8 months to 14 years during 1999-2003 and 8 months to 10 years during 2004-2007. Approximately 2 million doses of measles vaccines were administrated each year during SIAs. Estimated from the National Notifiable Diseases Surveillance System, with a reliable internal consistency over years, the average annual incidences of measles before SIAs (1993-1998), during the first phase (1999-2003), and during the second phase (2004-2007) were 16.05, 9.10, and 2.46 cases per 100,000, respectively. The overall provincewide annual incidence decreased by 84.67%, from 12.12 cases per 100,000 in 2000 to 2.10 cases per 100,000 in 2007. The percentage of counties with annual incidence ≥10 cases per 100,000 decreased from 55% in 1993 to <1% in 2007. Compared with the pre-SIA period, the greatest decrease in annual incidence was 83.93% for the 10-14.9-year-old group and the smallest decrease was 46.16% for children <1 year old. The multiple-year SIAs targeting children in selected high-risk counties were effective in controlling measles in mountainous, impoverished, and multiethnic measles-endemic areas.

The impact of supplementary immunization activities on the epidemiology of measles in Tianjin, China

“…This may be one explanation for why a local/non-local disparity in measles incidence persisted in the two years after the 2008 SIA, but not after the 2010 SIA. Numerous studies in China have suggested that migrants are a cause of high measles incidence, 6,14,34 although a notable shortcoming has been that these previous studies did not quantify the disparity in rates between locals and non-locals. In fact, we found that the decrease in measles incidence over time was largely driven by decreases in incidence among non-locals.…”

Modeling the Impact of Alternative Immunization Strategies: Using Matrices as Memory Lanes

“…These results were robust to sensitivity analyses including a wide range of epidemiological and cost parameters (see S1 File —Parameters, data sources and manipulation). These conclusions were also insensitive to changes in the assumptions on the transmission dynamics of measles (Supplementary Data in S1 File ) and should be helpful in informing ongoing policy debates over the use of SIAs [ 20 – 23 ].…”

The Polio Eradication and Measles Elimination: What We Learnt What Need We Do

“…More aggressive outreach programs to identify unregistered children have been conducted by township and village health care workers to increase the coverage of measles, polio, and other vaccines. Consequently, the numbers of children registered by EPI workers has been increasing continuously: the estimated coverage of measles vaccine among 1-4 year-olds increased from, 80% in 2001 to.97%in 2006, and the incidence of measles in Guangxi province as a whole decreased by 86%, from 13.32/100,000 in 2001 to 1.87/100,000 in 2006, 0.53/ million and 0.57/1million in 2010 and 2011 respectively [6].…”