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.

Sunday, 16th of February 2014

[source]PLoS One[|source]

A routine two-dose, single-antigen, live attenuated measles vaccine has been available for children administered the first dose in 8-12 months and the second dose at 7 years old in the Jiangsu province of China since 1978. In 1997, the age for the second dose was lowered to 4 years of age. The routine measles vaccination schedule was changed in 2006 to administration of the measles vaccine at 8 months of age followed by the measles, mumps, and rubella (MMR) vaccine at 18 to 24 months of age. Since 2007, measles epidemiology in Jiangsu province has changed. The highest incidence of measles occurred in children less than 5 years old, especially among children less than 8 months of age. In the same period, the incidence of measles among adults also increased, with most cases occurring among individuals 20–30 years of age.

In this report, the authors present  seroprevalence surveys 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. The report documented that vaccine-induced measles antibodies (Geometric Mean Titres) wane with time and is lowest in 15-29-year-olds.  More findings and recommendations 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 to14 years old and 20-29 years old. Additional SIAs are likely required to eliminate measles in China.