Persistence of rubella antibodies after 2 doses of measles-mumps-rubella vaccine.
BACKGROUND
Since 1990, most schoolchildren in the United States have received a second dose of measles-mumps-rubella vaccine (MMR2) at kindergarten entry. Elimination of endemic rubella virus circulation in the United States was declared in 2004. The objective of the current study was to evaluate the short- and long-term rubella immunogenicity of MMR2.


METHODS
At enrollment in 1994-1995, children (n = 307) in a rural Wisconsin health maintenance organization received MMR2 at age 4-6 years. A comparison group of older children (n = 306) was vaccinated at age 9-11 years. Serum specimens were collected during a 12-year period. Rubella antibody levels were evaluated by plaque-reduction neutralization (lowest detectable titer, 1:10).


RESULTS
Before administration of MMR2 in the kindergarten group, 9% of subjects were seronegative, 60% had the lowest detectable titer, and the geometric mean titer (GMT) was 1:13. One month after administration of MMR2, 1% were seronegative, 6% had the lowest detectable titer, and the GMT was 1:42. Four-fold boosts occurred in 62% of subjects, but only 0.3% were immunoglobulin M positive. Twelve years after MMR2 administration, 10% were seronegative, 43% had the lowest detectable titer, and the GMT was 1:17. The middle-school group showed similar patterns.


CONCLUSIONS
Rubella antibody response to MMR2 was vigorous, but titers decreased to pre-MMR2 levels after 12 years. Because rubella is a highly epidemic disease, vigilance will be required to assure continued elimination.
LeBaron
Charles W
CW
Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 16 Clifton Road, Atlanta, GA 30333, USA. clebaron@cdc.gov
Forghani
Bagher
B
Matter
Lukas
L
Reef
Susan E
SE
Beck
Carol
C
Bi
Daoling
D
Cossen
Cynthia
C
Sullivan
Bradley J
BJ
D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007117:Immunization, Secondary; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000276:immunology*; D012307:Risk Factors; D014922:Wisconsin
D000914:Antibodies, Viral; D022542:Measles-Mumps-Rubella Vaccine; C040901:rubella antibodies