No data are available to establish whether RZV is safe in pregnant or lactating women. recombinant ?zoster vaccine, ?Zoster ?Vaccine ?Live, vaccination strategies Varicella: background Epidemiology Varicella zoster virus (VZV) is a highly contagious, neurotropic -herpesvirus that infects humans, with no animal reservoir. Primary infection, usually during childhood, causes varicella. The virus remains latent in the sensory nerve ganglia and subsequently, due to the waning cellular immunity (CMI) to VZV (due to aging or some immunosuppressing states), can reactivate, causing herpes zoster (HZ).1,2 VZV is ubiquitous, however it is difficult to estimate its Ginsenoside F3 global burden, mainly because the only available data come from non-homogeneous surveillance systems. Most data on the epidemiology of varicella are from high-income countries; in this area, in the pre-vaccination era, 90% infections occurred before adolescence and less than 5% of adults remained susceptible to the virus.3 Conversely, in many tropical areas, the acquisition of the infection occurred in older age, with consequent greater susceptibility among young adults (14C19%, 26% and up to Ginsenoside F3 50% of susceptible adults in Saudi Arabia, India and Sri Lanka, respectively).4 The reasons for this difference in the age of acquiring primary VZV infection are poorly understood and probably include the influence of climate, population density and the risk of exposure of subjects to the pathogen. Varicella shows a strong seasonality in temperate environments and in most tropical areas, with peaks of incidence in winter and spring, or in the coldest and driest months in the tropics.5 In the pre-vaccination era, the epidemic peaks occurred with an inter-epidemic cycle of 2C5 years.6 The annual incidence rates of varicella in Europe, before the introduction of vaccination, were estimated between 7.05 (Greece) and 16.1 (Netherlands) for 100,000 5-year-old children, corresponding respectively to seroprevalence rates of 35.3% and 80.6%.7 In many countries, the annual incidence of varicella corresponded roughly to a birth cohort. 8 Clinical aspects Although varicella is usually a self-limiting disease, serious complications can occur in pediatric patients, mediated by the virus or by a secondary bacterial infection. Furthermore, VZV infection in adulthood is related to more serious symptoms and longer clinical course than in children. Globally, serious complications, with hospitalization, are estimated around 4.2 million per year.9 The extra-cutaneous complications affecting the central nervous system range from cerebellar ataxia (1 case in 4,000) for which the prognosis is usually good, to encephalitis (1 in 33,000C50,000 cases). Rarely, (about 1 in 40,000 cases) these complications can lead to death, especially among Ginsenoside F3 immunocompromised subjects.10 The most common complications are secondary bacterial infections of the skin and soft tissues in children and pneumonia, usually viral, in adults. The groups at highest risk for serious complications and death ICAM2 are newborns, pregnant women and severely immunocompromised individuals. Varicella acquired in the first trimesters of gestation can cause serious congenital diseases in the newborn in about 1C2% of affected pregnancies.11 VZV infection in pregnant women, even if rare, can lead to very severe manifestations, both in the mother and in the fetus. Newborns are at risk especially if the mother develops varicella within 5 days before or 2 days after delivery. Historically, the mortality rate for congenital varicella was about 30%, but the availability of VZV immunoglobulins and intensive supportive therapy reduced mortality of about 7%.12 Globally, specific mortality for varicella is considerably lower than deaths due to the other infectious diseases such as measles, pertussis, rotavirus or invasive pneumococcal infection; however, varicella cannot be deemed a trivial infectious disease, considering its complications. The mortality rate for varicella, in high-income countries, in the pre-vaccination era, was about 3 in 100,000 cases.11 In 2010 2010, the mortality rate was 0.1 per 100,000 in comparison to 1.7 and 1.1 for measles and pertussis, respectively.6 The introduction and implementation of universal vaccination in many European countries and.