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Canadian Journal of Infectious Diseases
Volume 8, Issue 2, Pages 85-88
http://dx.doi.org/10.1155/1997/215383
Original Article

Rubella Antibody Levels in School-Aged Children in Newfoundland: Implications for a Two-Dose Rubella Vaccination Strategy

Samuel Ratnam, Roy West, Veeresh Gadag, Brett Williams, and Elizabeth Oates

The Newfoundland Public Health Laboratory, Department of Health and Division of Community Medicine, Faculty of Medicine, Memorial University of Newfoundland, St John’s, Newfoundland, Canada

Received 11 June 1996; Accepted 14 September 1996

Copyright © 1997 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

OBJECTIVE: To determine the prevailing levels of rubella immunity among school-aged children who received a single dose of measles-mumps-rubella (MMR) vaccine at one year of age.

DESIGN: Cross-sectional study with a two stage cluster sampling of randomly picked schools across the province of Newfoundland.

STUDY POPULATION AND METHODS: A total of 1053, five to 17-year-old children were enrolled; vaccination history was verified through official records; and a sample of blood was taken. Rubella immunity was determined by enzyme immunoassay based on a serum antibody protective cut-off titre of more than 10 IU.

RESULTS: A total of 145 (13.8%) were found to be nonimmune. The rate of susceptibility ranged from 3.2% to 25.9% for different age groups. The proportion susceptible was significantly higher at 16.5% in the age group eight to 17 years old versus 3.9% for the age group five to eight years old (χ2=24.08; df=1, P<0.001). There was a significant regression of logarithm titre values on the age of children with an average decline in titre values of 8.1% per annum.

CONCLUSIONS: A substantial number of those who were given a single dose of MMR II vaccine may not have protective immunity against rubella as they reach prime reproductive age. There is a definite need to consider a two-dose rubella vaccination strategy in Canada, and these data suggest the second dose given after eight years of age will be most beneficial. In the move towards a routine two-dose measles vaccination strategy in Canada, the MMR II vaccine is being used for the second dose and given either at 18 months of age or at school entry. While this approach will have an overall beneficial effect, the impact of the above timing of the second dose on long term rubella immunity cannot be predicted at this time. These data also underscore the continuing need for prenatal rubella screening program.