Who is most at risk of contracting varicella?
- Infants younger than 1 year
- People over the age of 15 years
- Pregnant women
- Individuals with a weakened immune system
Varicella often takes a more severe course in individuals with impaired immunity – for example those with human immunodeficiency virus – due to malnutrition, illness or therapy. 1-6
Herpes zoster occurs when latent VZV reactivates and causes recurrent disease. 1
Varicella in pregnancy can be serious for the mother, with an increased risk of pneumonia, and other severe complications. 2
Groups at higher risk for severe complications are neonates, infants, pregnant women, adults and immunocompromised persons. 79In neonates, varicella can be life-threatening, especially if the mother develops varicella within 5 days before, or 2 days after, delivery. 2
Congenital varicella syndrome (scarring on the skin, abnormalities in limbs, brain, and eyes, and low birth weight) occurs in 0.4–2% of children born to mothers who became infected with VZV during the first 20 weeks of gestation, though isolated cases of congenital varicella syndrome have been described when mothers were infected up to 28 weeks of gestation. Infants whose mothers had varicella during pregnancy have a higher risk of developing herpes zoster in the first years of life. 7
Where is varicella most common?
Varicella occurs worldwide and in the absence of a vaccination programme, affects nearly every person by mid-adulthood. The epidemiology of the disease differs between temperate and tropical climates. The reasons for the differences are poorly understood and may relate to properties of VZV (known to be sensitive to heat), climate, population density and risk of exposure (e.g. attendance at childcare facility or school or the number of siblings in the household). 10
In temperate regions, such as Europe and the United States, varicella continues to be a childhood disease, with more than 90% of children being seropositive for varicella before reaching adolescence. 1112Seasonal peaks of infection occur during late winter and early spring. 1In tropical climates, varicella is generally less prevalent in children and is more likely to affect adults. 13
- CDC. Chapter 22: Varicella. In: Hamborsky J, Kroger A, Wolfe S, eds. Epidemiology and prevention of vaccine-preventable diseases, 13th edn. Washington DC, USA: Public Health Foundation. 2015: 353–376. Available at: http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/varicella.pdf Last accessed June 2015.
- CDC. People at High Risk for Complications. 2014. Available at: http://www.cdc.gov/chickenpox/hcp/high-risk.html Last accessed June 2015.
- Levin MJ. Varicella vaccination of immunocompromised children. J Infect Dis 2008;197(Suppl 2): S200–S206.
- Jura E, Chadwick EG, Josephs SH, et al. Varicella-zoster virus infections in children infected with human immunodeficiency virus. Pediatr Infect Dis J 1989;8: 586–590.
- Kreth HW, Lee BW, Kosuwon P, et al. Sixteen years of global experience with the first refrigerator-stable varicella vaccine (Varilrix®). BioDrugs 2008;22: 387–402.
- Hill G, Chauvenet AR, Lovato J, et al. Recent steroid therapy increases severity of varicella infections in children with acute lymphoblastic leukemia. Pediatrics 2005;116: e525–e529.
- WHO. Varicella vaccines. WHO position paper. Wkly Epidemiol Rec 2014;25: 265–288.
- Schmader K, Gnann JWJ, Watson CP. The epidemiological, clinical, and pathological rationale for the herpes zoster vaccine. J Infect Dis 2008;197(Suppl 2): S207–S215.
- ECDC Guidance Varicella vaccination in the EU Available at https://ecdc.europa.eu/sites/portal/files/media/en/publications/Publications/Varicella-Guidance-2015.pdf Last accessed Nov 2017..
- WHO. Immunization, Vaccines and Biologicals; Varicella. 2013. Available at: http://www.who.int/immunization/diseases/varicella/en/ Last accessed June 2015.
- Aebi C, Fischer K, Gorgievski M, et al. Age-specific seroprevalence to varicella-zoster virus: study in Swiss children and analysis of European data. Vaccine 2001;19: 3097–3103.
- Reynolds MA, Kruszon-Moran D, Jumaan A, et al. Varicella seroprevalence in the U.S.: data from the National Health and Nutrition Examination Survey, 1999-2004. Public Health Rep 2010;125: 860–869.
- Heininger U, Seward JF. Varicella. Lancet 2006;368: 1365–1376.