Varicella (chickenpox) is an acute, highly contagious disease caused by varicella-zoster virus (VZV). Following infection, the virus remains latent in neural ganglia and in about 10-20% of cases it is reactivated to cause herpes zoster, or shingles, generally in persons over 50 years of age or immunocompromised individuals.
Almost one-third of the population will experience an outbreak of shingles during their lifetime.
VZV transmission occurs via droplets, aerosols, or direct contact with respiratory secretions, and almost always produces clinical disease in susceptible individuals.
Varicella is characterized by an itchy, rash initially accompanied by fever and malaise. The rash gradually spreads to the trunk and extremities. The vesicles gradually dry out and crusts appear which then disappear over a period of one to two weeks.
While mostly a mild disorder in childhood, varicella tends to be more severe in adults. It may be fatal, especially in neonates and in immunocompromised persons.
The infection may occasionally be complicated by pneumonia or encephalitis (inflammation of the brain), at times with serious or fatal consequences.
In the United States, around 4 million annual varicella cases were reported with 100–150 deaths and > 10,000 hospitalisations before the introduction of routine varicella vaccination.
After the introduction of vaccination, the number decreased to fewer than 1,400 hospitalisations and less than 30 deaths.
The incidence of shingles in the US is of about 5 / 1,000.
Live-attenuated virus (1)
mRNA (1)
Phase I (1)
Phase II (1)
Paediatric (1)
Adults (1)
mRNA (1)
Phase II (1)
Adults + Older adults(1)
Sources:
CDC. Shingles Burden and trends. 2023. Available at: https://www.cdc.gov/shingles/surveillance.html
WHO. Varicella and herpes zoster vaccines: WHO position paper, June 2014. 2024. Available from: https:// www.who.int/publications/i/item/who-wer-8925-265-288.
CDC. Chickenpox Vaccine Saves Lives and Prevents Serious Illness Infographic. 2024. Available from: https://www.cdc.gov/chickenpox/vaccine-infographic.html.
[Accessed: August 2024]
