[Herpes Zoster and its prevention in Italy. Scientific consensus statement]

Abstract

In this paper, an Italian group of experts presents a revision of the available data about epidemiology and prevention of Herpes Zoster (HZ). HZ is an acute viral diseases caused by the reactivation of Varicella Zoster Virus (VZV). HZ is characterized by neurological and dermatological symptoms with a dermatomeric localization. The reactivation of the virus from the latent status in the sensitive ganglia increases with age and failing cell mediated immunity. In Europe, more than 95% of adults presents antibodies against VZV. Incidence of HZ is similar all over the world, related to the age of the population: from 2-3/1000 persons/year in the age group 20 to 50 years to 5/1000 in the 60 years old, 6-7/1000 between 70 and 80 up to >1/100 in older than 80. In Italy, about 157,000 new cases of HZ are estimated every year with an incidence of 6.3/1000 persons/year mostly in older adults. Among the hospitalized cases, 60% are over 65 years of age. The more frequent and severe complication of HZ is post herpetic neuralgia (PHN), characterized by severe localized pain lasting at least 3 month after the beginning of the acute phase. The pain is responsible for a sharp decrease in the quality of life. In Europe, PHN is described in 2.6-27% of HZ cases. In Italy, data obtained by a network of General Practitioner show PHN in 20.6% of HZ patients, while 9.2% of the patients still presents PHN at 6 months. The more frequent localization is thoracic; when the virus reactivate at the level of the ophthalmic division of the trigeminal nerve most patients develop ocular complications. The clinical and therapeutical managements of HZ patients is difficult and the results are often poor. Prevention of HZ e PHN in the population over 50 years is possible using a live attenuated vaccine containing VZV (Oka/Merck strain, not less than 19.400 plaque forming units), available since 2006. Efficacy of anti-HZ vaccine was demonstrated in two large clinical trials that showed a 51% reduction in the incidence of HZ and a 61% decrease of the burden of illness. Incidence of PHN showed a reduction of 67% in immunized subjects. Long-term follow-up showed a persistence of the protection even if a decrease was noted in older subjects and with time. Effectiveness studies confirm the data of clinical trials and numerous pharmaco-economical evaluation show a favorable profile of HZ vaccine. The vaccine is recommended in USA, Canada and some European countries for people over 60. The expert group concluded that HZ and PHN represent an important clinical and Public Health problem in Italy and that the possibility to prevent them should be carefully evaluated.