Age-related changes in serological susceptibility patterns to measles: results from a seroepidemiological study in Dongguan, China.

The present study was performed to determine the seroprevalence of IgG measles antibodies in Dongguan residents (irrespective of vaccination status), to analyze the changes in age-related serological susceptibility patterns. A total of 1960 residents aged 0-60 years and 315 mother-infant pairs were studied. Serum IgG antibodies against measles virus were measured by ELISA. The overall seroprevalence was 93.4% in the general population in Dongguan, China. In subgroups aged 1-29 years who were likely vaccinated, there was a declining trend of seropositivity with age from 98.6% at 1-4 years to 85.7% at 20-29 years (P<0.0001). Seroprevalence were near or>95% in the older population (30-39 years and ≥ 40 years) who had not been immunized against measles. Age and sex were independent factors associated with seropositivity. Seroprevalence in pregnant women and their newborns was 87.0% and 84.1%, respectively. Our results suggest that the waning vaccine-induced immunity may be the main cause of increased serological susceptibility in young adults and young infants. An additional vaccination strategy that targets young adults is important for elimination of measles.