CROSS-SECTIONAL SURVEYS OF MEASLES ANTIBODIES IN THE JIANGSU PROVINCE OF CHINA FROM 2008 TO 2010: THE EFFECT OF HIGH COVERAGE WITH TWO DOSES OF MEASLES VACCINE AMONG CHILDREN

Monday, 25th of August 2014

[source]PLoS One[|source]

Since 2007, changes in the epidemiological characteristics of measles had been observed in the Jiangsu province. At the time, the highest incidence of measles occurred in children less than 5 years old, especially among children less than 8 months of age. The incidence of measles among adults also was documented to have increased, with most cases occurring among individuals 20–30 years of age. Catch-up supplemental immunization activities among children from 8 months to 15 years old were conducted in 2009 to achieve high levels of population immunity and rapidly interrupt the chain of measles virus transmission in the province. Follow-up SIAs among children from 8 months to 5 years of age were conducted in 2010.

Measles seroprevalence surveys were conducted in the Jiangsu province from 2008 to 2010 to track changes in population immunity year by year and to identify the susceptible or high-risk cohorts to help target immunization activities. In this study, authors report that measles sero-prevalence is variable by age and conclude that vaccination strategies need to be adjusted to the variations in sero-epidemiology, which in turn vaires by region. More details are accessible at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3692513/

 

ABSTRACT

BACKGROUND: Changes in the epidemiological characteristics of measles since 2007 appeared in the Jiangsu province. Although the reported coverage with two doses of measles vaccine was greater than 95% in most regions of the province, measles incidence remained high across the whole province. Cross-sectional serological surveys of measles antibodies in the Jiangsu province of China were conducted from 2008 to 2010 to assess and track population immunity.

METHODS:  Measles-specific IgG levels were measured in serum samples using ELISA. GMTs and seroprevalence with 95% CIs were calculated by region, gender, and age. ANOVA and χ² tests were used to test for statistically significant differences between groups for GMT levels and seroprevalence, respectively.

RESULTS: Seroprevalence showed a significantly increasing trend annually (CMH χ²=40.32, p<0.0001). Although the seroprevalence among children aged 2–15 years was consistently over 95%, vaccine-induced measles antibodies may wane over time. Measles seropositivity in the Jiangsu province was 91.7% (95% CI: 90.1–93.2%) in 2010. Among adults aged 15 to 29-year-olds, the seropositivity rate was 88.4% (95% CI: 82.7–92.8%).

CONCLUSIONS: Vaccination strategies may need to be adjusted depending on the individual age and regions, particularly individuals between the ages of 8 months-14 years old and 20–29 years old. Additional SIAs are likely required to eliminate measles in China.