Aim-To evaluate the risk factors for breakthrough varicella in a follow up study of a cohort of 181 healthy children immunised when aged 9-24 months with a reformulated Oka strain varicella vaccine (SmithKline Beecham Biologicals/Oka).
Design-The children were randomised in a double blind manner into one of four groups to receive one of two production lot vaccine batches, at two different titres (high titre, 103.9 and 104.0 plaque forming units (pfu) ; low titre (heat exposed), 102.7 and 102.8 pfu).
The overall seroconversion rate after immunisation was 99%. Results-One hundred and sixty eight patients were available for review after a mean (SD) follow up of 35 (9) months after vaccination.
Multivariate analysis indicated that risk factors for breakthrough varicella were household contact with varicella (adjusted odds ratio (OR), 19.89 ; 95% confidence interval (CI), 18.39 to 21.39), vaccination age of <= 14 months (adjusted OR, 2.30 ; 95% CI, 1.69 to 2.90), and receiving low titre (102 pfu) vaccine (adjusted OR, 2.13 ; 95% CI, 1.54 to 2.73).
All children who developed breakthrough varicella, had a modified varicella illness, except for three, all of whom had received low titre vaccine.
Conclusion-The identification of young immunisation age (<= 14 months) and low titre vaccine as risk factors for breakthrough varicella have important implications for the implementation of varicella vaccination programmes in healthy children.
Mots-clés Pascal : Varicelle, Virose, Infection, Vaccination, Immunisation, Long terme, Etude cohorte, Etude statistique, Etude double insu, Facteur risque, Age, Titre, Vaccin, Singapour, Asie, Nourrisson, Homme, Enfant, Virologie, Epidémiologie
Mots-clés Pascal anglais : Varicella, Viral disease, Infection, Vaccination, Immunization, Long term, Cohort study, Statistical study, Double blind study, Risk factor, Age, Title, Vaccine, Singapore, Asia, Infant, Human, Child, Virology, Epidemiology
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0025775
Code Inist : 002B05A02. Création : 31/05/1999.