Varicella (chickenpox) is a highly contagious illness sustained by an α Herpes virus called
varicella-zoster virus (VZV). A replication phase in the penetration site is followed by a
viremic phase when VZV spreads to skin and mucosae, leading to the typical rash and infection
of sensory nerves in the epithelium, and then the reach of the sensory ganglia where it
becomes latent. The reactivation of the latent virus, years or decades after primary
infection, causes the typical clinical expression called Herpes Zoster (HZ) or shingles.
Post-herpetic neuralgia (PHN), an intractable pain in the dermatome affected by HZ, is the
most common complication. It is estimated that it affects 10-20% of all patients with HZ aged
≥ 50 years and up to 30% of those aged ≥80 years. Management of PHN is not easy, but
vaccination for prevention of PHN may be a strategic choice.
The most common complications of herpes zoster, other than PHN, often requiring
hospitalization, include secondary bacterial infections, ophthalmic complications, cranial
and peripheral nerve palsies, and segmental zoster paresis.
All authors agree that factors such as age, cell-mediated immunity (CMI) depression,
intrauterine exposure to VZV and varicella occurring in early age (<18 months) are typically
associated with HZ incidence. It further should be noted that age and CMI depression are
strictly related since increasing age leads to CMI decrease. An increased incidence of
hospitalization for HZ among patients aged >72 years (0.46/1000-person year), compared to
those aged 15-44 years (0.03/1000-person year) was reported, suggesting that aging is also a
risk factor for HZ requiring hospitalization. Besides age, HZ risk can be related to other
co-morbidities, including diabetes, major depression or immunosuppressive therapies, that
induce reduced VZV-specific CMI response. Immunosuppressed patients are within the high-risk
group, with increasing morbidity and mortality associated with herpes zoster.
Immunosuppression may be associated with malignancy (especially hematological), human
immunodeficiency virus (HIV) infection or medications used for organ transplantation or
autoimmune disease.
HZ incidence is similar all over the world and its trend is related to population age, with
two thirds of the cases affecting subjects aged >50 years.
Among European adult population, the percentage of subjects estimated to be seropositive for
anti-VZV antibodies is 95%: all of them are therefore potentially susceptible to develop HZ
in their lifetime. In Italy, the annual incidence of HZ is 6.3/1000 person-years, with 73% of
cases affecting adults.
Italy is one of the countries with the highest proportion of elderly people in its
population, and yet data on the epidemiology of HZ and PHN are limited. As the immune system
weakens with increasing age, many infectious diseases, such as HZ, are more severe and more
closely associated with long-term consequences in the elderly than in younger people. With
the growing aging population, a rise in the number of cases of HZ in the near future is
expected; thus, this disease will become a public health issue. While awareness of childhood
vaccination is well established, the prevention of infectious diseases in groups other than
children is a challenging, yet fundamental, objective that public health systems should
pursue in order to promote healthy aging.
In order to evaluate the epidemiological burden of HZ, hospital discharge records for HZ
between 2011 and 2021, with or without complications, will be extracted from the national
hospital discharge database (HDD).
The characteristics of hospitalizations will be described for the 18 years of age and older
adults (2011-2021 years).
The characteristics of hospitalizations in 2020-21 will be described in patients with or
without concomitant COVID-19 infection.