Humoral and cell-mediated immune responses to an early 2-dose measles vaccination regimen in the United States.
BACKGROUND
Shifts in peak measles incidence to children <12 months old and the associated high mortality support the study of an early 2-dose measles vaccine regimen.


METHODS
Fifty-five infants were vaccinated with measles vaccine at age 6 (n=32) or 9 (n=23) months, followed by measles-mumps-rubella (MMR)-II vaccine at age 12 months. A control group received MMR-II only at age 12 months. Measles-specific humoral and cell-mediated immunity were evaluated before, 12 weeks after measles immunization, and 24 weeks after MMR-II.


RESULTS
Measles-specific T cell proliferation after both doses of vaccine was equivalent, regardless of age or the presence of passive antibodies. Seroconversion rates, geometric mean titers, and the percentage of infants with antibody titers >120 mIU after the first measles vaccine were lower in infants vaccinated at age 6 months, regardless of the presence of passive antibodies, but measles humoral responses increased after the administration of MMR-II vaccine in children initially vaccinated at age 6 or 9 months.


CONCLUSIONS
Measles vaccination elicits T cell responses in infants as young as 6 months old, which may prime the humoral response to the second dose. Initiating measles vaccination as an early 2-dose regimen results in an immunologic response that is likely to have clinical benefits in developed and developing countries.
Gans
Hayley A
HA
Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305-5208, USA. hagans@stanford.edu
Yasukawa
Linda L
LL
Alderson
Amanda
A
Rinki
Mary
M
DeHovitz
Ross
R
Beeler
Judith
J
Audet
Susette
S
Maldonado
Yvonne
Y
Arvin
Ann M
AM
D000914:Antibodies, Viral / Q000097:blood*; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D008213:Lymphocyte Activation; D008457:Measles / Q000276:immunology / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage* / Q000276:immunology; D008459:Measles virus / Q000276:immunology*; D022542:Measles-Mumps-Rubella Vaccine / Q000008:administration & dosage* / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D016896:Treatment Outcome; D014611:Vaccination
D000914:Antibodies, Viral; D008458:Measles Vaccine; D022542:Measles-Mumps-Rubella Vaccine