Varicella and herpes zoster incidence prior to the introduction of systematic child vaccination in Navarre, 2005-2006

Abstract

Varicella is an acute and highly contagious disease produced by the varicella-zoster virus, which leaves lasting immunity. Herpes zoster is produced by reactivation of a latent infection of the same virus. The introduction of systematic and free vaccination against varicella in children of 15 months in Navarre from 2007 onwards can be expected to produce important epidemiological changes. For this reason we describe the previous epidemiological situation in the period from 2005 to 2006. We analysed all cases of varicella and herpes zoster registered in the electronic clinical files of primary care, in the database of hospital discharges and in the mortality register. Between 2005 and 2006, 9,908 cases of varicella were diagnosed (8.29 annually per 1,000 inhabitants), with 90% in children under 15 years old. There were 80 hospital admissions (8 for every 1,000 cases), complications in 2.5 out of every 1,000 cases, and there was one death due to this cause (0.1 per 1,000 cases). In the same period, 4,959 cases of herpes zoster were diagnosed (4.15 cases per 1,000 inhabitants), half in people over 55 years old. There were 179 hospital admissions (36 per 1,000 cases), whose average age was 77, and 83 presented complications (16.7 per 1,000 cases). This epidemiological pattern is similar to that found in other places before the introduction of the vaccine.