Assessment of the effectiveness of the universal varicella vaccination program in Toscana (Italy), in the period 2010-2013.
OBJECTIVE
To assess the effectiveness of the varicella vaccination program in Toscana after one dose of vaccine, in the birth cohorts 2008-2011.


METHODS
Varicella vaccine effectiveness (VE) was calculated using the "screening method", based on vaccine coverage (VC) at 24 months and proportion of vaccinated subjects among varicella notified cases (PVC), verified through the Local Health Units' (LHUs) immunization registries. Breakthrough varicella (BV) was defined as a case of varicella occurring in a child vaccinated ≥42 days before the date of disease onset.


METHODS
The study was conducted in the 12 Tuscan LHUs and included all varicella cases notified in 2010-2013 in children of the birth cohorts 2008-2011.


METHODS
BV cases; VE after one dose of varicella vaccine; time interval between varicella vaccination and symptom onset.


RESULTS
VC was 79.8%, VE reached 90.8%(95%CI 89.5%-92.0%) and the proportion of BV among notified cases was 26.6%. The median time interval between vaccination and symptom onset was 25 months.


CONCLUSIONS
The very low rate of BV cases among vaccinated children confirms the high effectiveness even of a single dose of varicella vaccine and does not support a change of the current immunization schedule.
Scuola specializzazione in Igiene e medicina preventiva, Università di Firenze, Italy. pieriluca@gmail.com.
Luca
L
Pieri
Scuola specializzazione in Igiene e medicina preventiva, Università di Firenze, Italy.
Barbara Rira
BR
Porchia
Scuola specializzazione in Igiene e medicina preventiva, Università di Firenze, Italy.
Francesca
F
Pieralli
Scuola specializzazione in Igiene e medicina preventiva, Università di Firenze, Italy.
Ornella
O
Varone
Scuola specializzazione in Igiene e medicina preventiva, Università di Firenze, Italy.
Giuditta
G
Niccolai
Dip. Prevenzione, ASL 4 Prato, Italy.
Annalisa
A
Roselli
Dip. Scienze della salute, Università di Firenze, Italy.
Sara
S
Boccalini
Dip. Scienze della salute, Università di Firenze, Italy.
Paolo
P
Bonanni
Dip. Scienze della salute, Università di Firenze, Italy.
Angela
A
Bechini
D002644:Chickenpox / Q000453:epidemiology / Q000523:psychology*; D019433:Chickenpox Vaccine; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data; D007115:Immunization Schedule; D007558:Italy; D008297:Male; D015397:Program Evaluation; D013997:Time Factors; D014613:Vaccines, Attenuated
D019433:Chickenpox Vaccine; D014613:Vaccines, Attenuated