Flexibility Of Immunisation Regimens Of GlaxoSmithKline Varicella Vaccine In Healthy Adolescents And Adults

Kosuwon P.¹, Wasi C.², Hutagalung Y.³, Bock H.L.³

¹Department of Pediatrics, Khon Kaen University, Khon Kaen, Thailand; ²Department of Microbiology, Mahidol University, Bangkok, Thailand; ³GlaxoSmithKline Biologicals, Rixensart, Belgium

Objective: To assess immunogenicity and reactogenicity of the GlaxoSmithKline Biologicals’ live attenuated varicella vaccine, given at two doses in healthy seronegative adolescents and adults.

Methods: One hundred adolescents (mean age of 15.2 years) and 60 adults (mean age of 19.1 years) were enrolled in a multicenter trial conducted in Thailand, and were administered 2 doses of varicella vaccine (OKA strain, Varilrix^TM, GlaxoSmithKline Biologicals). The interval between administration of the 2 doses was 8 and 4 weeks for adolescents and adults respectively. Blood samples were taken 1 to 10 days before first vaccination (Pre-I), immediately before second vaccination (Post-I/Pre-II), and 6 weeks after the second vaccination (Post-II). Local and systemic reactions were recorded in diary card by the vaccinees. Anti-varicella titers were measured by immunofluorescent assay.

Results: In both groups, all subjects (ATP cohort) were seropositive for anti-varicella antibodies, immediately before administration of the second dose (Post-I/Pre-II). Geometric mean titers (GMT) for anti-varicella antibodies were 78.4 for the adolescent group and 136.5 for the adult group. Six weeks after administration of the second dose (Post-II), anti-varicella GMTs reached 331.7 and 636.9 for the adolescents and adults groups respectively. For both groups, the difference between GMTs was statistically significant.

Group	Timing	N	Seropositivity		GMT	95 % CI
			n	%
Adolescents	Post-I/Pre-II	99	99	100	78.4	63.3 - 97.2
	Post-II	99	99	100	331.7	276.0 - 398.6
Adults	Post-I/Pre-II	54	54	100	136.5	98.6 - 188.9
	Post-II	54	54	100	636.9	511.1 - 793.5

Local and general reactogenicity observed after administration of the first and second doses of vaccines was mild, and no varicella rash was reported. Finally, no relevant difference between both groups, receiving the vaccine at different intervals, was observed.

Conclusion: Two doses of GlaxoSmithKline varicella vaccine are well tolerated and highly immunogenic, and can be given at 4 or 8 weeks interval in adults and adolescents.

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