Varicella

Varicella, also commonly referred to as “chickenpox”, is an acute and highly contagious disease. It is caused by primary infection with the varicella-zoster virus (VZV). Varicella occurs worldwide and in the absence of a vaccination programme, affects nearly every person by mid-adulthood. VZV is highly transmissible via respiratory droplets or direct contact with characteristic skin lesions of the infected person. The first symptoms of clinical varicella generally appear after a 10-21 day incubation period and include fever, malaise and the characteristic itchy rash.

Varicella is generally self-limited and vesicles gradually develop crusts, which disappear over a period of 7-10 days. Individuals remain contagious until all lesions have crusted over. The disease is typically mild, but severe complications may arise, including bacterial infections (e.g. cellulitis, pneumonia) and neurological complications (e.g. encephalitis), and these can be fatal. Disease is associated with higher morbidity and mortality in infants and in individuals with an impaired immune system.

Varicella can be prevented by immunization and multiple vaccine formulations of the live attenuated vaccine. Varicella vaccines are available as a single antigen and in combination with measles, mumps and rubella vaccine. It is not known how long a vaccinated person is protected against varicella. But, live vaccines in general provide long-lasting immunity.

Several studies have shown that people vaccinated against varicella had antibodies for at least 10 to 20 years after vaccination. Those who had chicken pox do not need to get varicella vaccination

The varicella vaccine is given in two doses.

A child should have the first shot at ages 12-18 months. The second shot should be given at ages 4-6 years.

Older children and adults should have two shots, with four to eight weeks between the first and second shot