- Varicella (chickenpox), a highly contagious viral infection that occurs worldwide (especially in developing countries), is acquired via inhalation of aerosolized respiratory droplets or blister fluid from infected persons as well as by direct contact with blister fluid.
- Risk of infection exists for all unvaccinated children and young adults (born in 1980 or later) in the U.S. who have not previously been infected.
- Symptoms are mild and include fever, malaise, and itchy, fluid-filled skin blisters that become scabs.
- Consequences of infection include bacterial infection of skin lesions in children, pneumonia in adults, and herpes zoster (shingles) when the dormant varicella virus is reactivated many years later.
- Prevention includes observing good respiratory hygiene (cough and sneeze etiquette), frequent, thorough handwashing, and avoiding infected persons.
- Varicella vaccine (live) is routinely given as 2 doses to children, 1 dose each at ages 12-15 months and 4-6 years. Regardless of travel, all persons 4 years and older, born in 1980 or later, and without history of disease or of 2 countable doses of live vaccine at any time during their lives should complete a lifetime total of 2 doses of varicella vaccine (spaced by at least 28 days).
- Vaccine side effects are most commonly injection-site reactions, fever, and a generalized varicella-like rash.
- Duration of vaccine protection following the first dose (adequate for travel) is 4 to 5 years and following the second dose is long-lasting; no booster dose is recommended.
Chickenpox is a highly contagious infection caused by varicella zoster virus, resulting in fever and itchy, fluid-filled skin blisters that become scabs. Infection is usually mild in healthy children younger than 15 years, but can be serious, especially in young infants, adolescents, adults (especially pregnant women), and persons with a weakened immune system. The virus remains dormant in the body after infection and can later reactivate to cause shingles.
Chickenpox occurs worldwide and is prevalent in all countries worldwide. Even in the U.S., where childhood vaccination is routine, 10,000 cases occur annually. In temperate climates, peak incidence among children occurs in the winter and early spring. In tropical countries, the highest incidence is in the dry, cool months. The disease tends to be acquired later in childhood, resulting in increased susceptibility among adults.
Chickenpox is primarily transmitted from person to person via inhalation of aerosolized respiratory droplets (e.g., by cough or sneezing) or blister fluid of infected persons as well as by direct contact with blister fluid. Varicella is contagious from 2 days before symptom onset until the last lesion scabs over, typically 4 to 7 days after rash onset.
Risk of infection exists for anyone not protected against chickenpox, including travelers, regardless of destination. Persons at highest risk for severe infection or complications include newborns and premature infants; children with leukemia or lymphoma; adults; and persons with weakened immune systems, who have HIV or AIDS, or are pregnant.
Symptoms appear 10 to 21 days following exposure. An itchy rash starts on the head, chest, and back before spreading to the rest of the body; the lesions progress to blisters before crusting over. Healthy children usually have a mild infection. Adults may experience fever and malaise up to 2 days before the rash occurs and are at higher risk of severe disease.
Consequences of Infection
Bacterial infection of skin lesions in children and pneumonia in adults can occur. Following infection, the varicella virus can reactivate at any time causing shingles; see Herpes Zoster).
Need for Medical Assistance
Susceptible persons (especially pregnant women and those with weakened immune systems) who have been exposed to chickenpox should seek medical attention. Varicella vaccine, if given within 5 days of exposure, can prevent or reduce the severity of illness. Varicella zoster immune globulin can be used for those who cannot receive the vaccine.
Observe good respiratory hygiene (cough and sneeze etiquette) and frequent, thorough handwashing. Avoid persons with illness or skin lesions consistent with chickenpox or shingles.
Varicella vaccine (live) is given routinely as a childhood vaccination and to all nonimmune, healthy, health care workers, pregnant women after delivery, and persons who are considered high risk. All travelers 12 months and older should be vaccinated unless immune. Natural chickenpox infection provides life-long immunity. A combination vaccine is also available.
The most common vaccine side effects are mild and include redness, soreness, swelling, and pain at the injection site; fever; and a generalized varicella-like rash (occurring within 3 weeks of vaccination). Serious side effects are rare but can include low blood platelets and various neurological conditions.
Persons with underlying medical conditions or who have concerns about the vaccine should speak to their health care provider before vaccine administration.
Varicella vaccine, regardless of travel, is given as follows:
- Routinely to children aged 1-6 years: 2 doses, 1 dose each at ages 12-15 months and 4-6 years. Children 4 years and younger only need the first dose prior to travel; an early second dose is not recommended.
- All persons 4 years and older, born in 1980 or later, and without history of disease or of 2 countable doses of live vaccine at any time during their lives: complete a lifetime total of 2 doses (spaced by at least 28 days).
- One dose before departure will provide protection for healthy persons.
Duration of vaccine protection following 1 dose is about 4 to 5 years and following a completed series (2 doses) is long-lasting and approximately 95% effective in preventing chickenpox. A booster dose is not recommended.