Immunogenicity and safety of a live attenuated varicella vaccine in healthy Indian children aged 9-24 months.
OBJECTIVE
To investigate the safety of live attenuated varicella vaccine (Oka strain) and the optimal virus titre/dose required for immunogenicity in healthy South African children.


METHODS
Double-blind randomised clinical study using two different lots of varicella vaccine, each at two different titres. Subjects were randomly allocated to groups 1, 2, 3 and 4 to receive vaccine containing a mean virus titre of 10(4,5), 10(3,1), 10(3,9) and 10(2,7) PFUs per dose respectively. Clinical signs and symptoms were followed up for 42 days post-vaccination. Specific varicella antibodies were measured by an indirect immunofluorescence method in sera obtained on day 0 and day 42.


METHODS
City Health Clinic, Chatsworth, Durban.


METHODS
A total of 200 healthy 9-24-month-old children were vaccinated, of whom 189 (44,5%) completed the study.


METHODS
Pre- and post-vaccination varicella antibody levels. Adverse events following varicella vaccination.


RESULTS
The vaccine was safe and well tolerated. No local symptoms were reported. Skin reactions were specifically solicited in this study: 21 reactions were reported in 8.5% (17/200) of children. Vesicles were reported in 2 vaccines (< or = 10 vesicles in both cases). One serious adverse event was reported: hospitalisation for bronchopneumonia on day 16 post-vaccination which resolved without sequelae. Around day 42 post-vaccination (range 35-63 days) all the 176 initially seronegative subjects had seroconverted for varicella antibodies. Post-vaccination geometric mean titres (GMTs) were 104.1, 66.2, 69.5 and 77.0 for groups 1-4 respectively. Six subjects who were initially seropositive maintained or increased their titres post-vaccination; 3 of the 6 showed a booster response (a > or = 4-fold increase from the pre-vaccination titre).


CONCLUSIONS
Varicella vaccine was found to be safe, immunogenic and well tolerated. No difference in seroconversion rates or GMTs, either between groups receiving the two vaccine lots or between groups receiving the different titres of each lot, was shown.
Ramkissoon
A
A
Department of Paediatrics and Child Health, University of Natal, Durban.
Coovadia
H M
HM
Jugnundan
P
P
Haffejee
I E
IE
Meurice
F
F
Vandevoorde
D
D
D000914:Antibodies, Viral / Q000097:blood; D019433:Chickenpox Vaccine; D002675:Child, Preschool; D004311:Double-Blind Method; D019084:Fluorescent Antibody Technique, Indirect; D014645:Herpesvirus 3, Human / Q000276:immunology*; D006801:Humans; D007223:Infant; D012449:Safety; D013019:South Africa; D014613:Vaccines, Attenuated / Q000009:adverse effects / Q000276:immunology*; D014765:Viral Vaccines / Q000009:adverse effects / Q000276:immunology*
D000914:Antibodies, Viral; D019433:Chickenpox Vaccine; D014613:Vaccines, Attenuated; D014765:Viral Vaccines