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Chickenpox Update as of March 27, 2017

Each year, nearly 700,000 cases of chickenpox are diagnosed in France, particularly among children under 10 years of age (more than 90% of cases), resulting in approximately 3,000 hospitalizations and 20 deaths (70% of those who died were over 10 years old). These data reflect the frequent and exceptionally severe nature of the disease in childhood, as well as the increased risk of complications with age. Chickenpox is a highly contagious viral disease, usually mild, that occurs primarily during childhood. Transmission occurs via the respiratory route, through inhalation of saliva droplets emitted by an infected person before symptoms appear, or through direct contact with skin lesions. It is caused by a herpes virus (Varicella-Zoster Virus or VZV). Chickenpox is the primary infection with VZV. The lifetime risk of contracting chickenpox is very high (approximately 95%), and the risk of experiencing at least one reactivation of the virus (shingles) is around 15 to 20%. More than 90% of the population is immune by the age of 10.Chickenpox has been monitored by the Sentinelles network since 1990 (and shingles since 2004). Each week, the network tallies the number of cases reported by its sentinel physicians, which it extrapolates to all French general practitioners to produce: an estimate of the number of cases that sought medical care in mainland France and maps describing their geographic distribution. Chickenpox is a "seasonal" disease for which a spring surge in the number of cases is observed every year (weeks 11 to 15); this is an expected increase in the disease (see figure). A second peak can also be observed in June/July (weeks 25 to 28). In France, widespread vaccination against chickenpox for children over 12 months of age is not recommended. Current vaccination recommendations apply to individuals with no history of chickenpox or with an uncertain history, under the following circumstances: adolescents aged 12–18, women of childbearing age, adolescents and adults who have been in contact with a case within 3 days of exposure, healthcare professionals and professionals working with young children, individuals in close contact with immunocompromised persons, and children who are candidates for solid organ transplantation. A serological screening prior to vaccination may (or must, depending on the circumstances) be performed.