[Seroprevalence of varicella-zoster virus antibodies after the recent introduction of the universal childhood immunisation schedule in the Community of Madrid].

BACKGROUND AND

OBJECTIVE

In November 2006, the Community of Madrid included the chickenpox vaccine into the immunisation schedule for children from 15 months of age. This was withdrawn in January 2014. Seroprevalence of antibodies to the virus is estimated after the first 2-3 years from the inclusion of the vaccine, and as well as its evolution since 1999.

MATERIAL AND METHOD: A cross-sectional study was conducted on the target population consisting of residents in the Community of Madrid between 2 and 60 years of age. Measurement of IgG antibodies was performed using an ELISA technique. Seroprevalence was estimated according to sociodemographic characteristics using multiple logistic regressions. The results are compared with previous surveys. Also, the seroprevalence and geometric mean of the antibody according immunisation status and history of the disease are presented. The confidence level used is 95%.

RESULTS

A total of 4,378 subjects were included, with a response rate of 69%. The estimated seroprevalence was 95.3% (95% CI: 94.6% - 95.9%). Over 90% of children from the age of 10 have antibodies. The seroprevalence was higher in people with less education. The seroprevalence of immunity vaccine exceeds 90% in the first year after vaccination, but in the second year decreased to 82.6% (95% CI 56.0 - 94.7). Significant differences, attributable to universal vaccination, were found compared to previous surveys.

DISCUSSION: Continued surveillance is needed in order to assess the impact of the withdrawal of the recommendation to vaccinate at 15 months.