Immunological impact of an additional early measles vaccine in Gambian children: responses to a boost at 3 years.
BACKGROUND
Measles vaccine in early infancy followed by a dose at 9 months of age protects against measles and enhances child survival through non-specific effects. Little is known of immune responses in the short or long term after booster doses.


METHODS
Infants were randomized to receive measles vaccine at 9 months of age (group 1) or 4 and 9 months of age (group 2). Both groups received a boost at 36 months of age. T-cell effector and memory responses using IFN-γ ELIspot and cytokine assays and antibody titres using a haemagglutination-inhibition assay were compared at various times.


RESULTS
Vaccination at 4 months of age elicited antibody and CD4 T-cell mediated immune responses .Two weeks after vaccination at 9 months of age group 2 had much higher antibody titres than group1 infants; cell-mediated effector responses were similar. At 36 months of age group 2 antibody titres exceeded protective levels but were 4-fold lower than group 1; effector and cytokine responses were similar. Re-vaccination resulted in similar rapid and high antibody titres in both groups (median 512); cellular immunity changed little. At 48 months of age group 2 antibody concentrations remained well above protective levels though 2-fold lower than group 1; T-cell memory was readily detectable and similar in both groups.


CONCLUSIONS
An additional early measles vaccine given to children at 4 months of age induced a predominant CD4 T-cell response at 9 months and rapid development of high antibody concentrations after booster doses. However, antibody decayed faster in these children than in the group given primary vaccination at 9 months of age. Cellular responses after 9 months were generally insignificantly different.
Medical Research Council Laboratories, Banjul, Gambia.
Jainaba
J
Njie-Jobe
Samuel
S
Nyamweya
David J C
DJ
Miles
Marianne
M
van der Sande
Syed
S
Zaman
Ebrima
E
Touray
Safayet
S
Hossin
Jane
J
Adetifa
Melba
M
Palmero
Sarah
S
Burl
David
D
Jeffries
Sarah
S
Rowland-Jones
Katie
K
Flanagan
Assan
A
Jaye
Hilton
H
Whittle
D000914:Antibodies, Viral / Q000276:immunology; D002675:Child, Preschool; D016207:Cytokines / Q000097:blood / Q000276:immunology; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005714:Gambia; D006801:Humans; D007117:Immunization, Secondary; D007156:Immunologic Memory; D007223:Infant; D007371:Interferon-gamma / Q000097:blood / Q000276:immunology; D008457:Measles / Q000276:immunology* / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology; D008459:Measles virus / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
D000914:Antibodies, Viral; D016207:Cytokines; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D008458:Measles Vaccine; D007371:Interferon-gamma