Chickenpox (Varicella) in Unvaccinated and Vaccinated Patients: Clinical Features

A mild prodrome of fever and malaise may come 1 to 2 days before the rash, especially in adults; in children, the rash is often the first sign.

Chickenpox in an unvaccinated child. CDC PHIL #6121

In unvaccinated patients

• The rash is generalized and itchy, moving quickly from macules to papules to vesicles before crusting — with lesions at all stages at once.
• It usually starts on the chest, back and face, then spreads everywhere, and is densest on the chest and back. Symptoms usually last 4 to 7 days.
• In healthy children it's generally mild: an itchy rash, malaise, and fever up to 102°F for 2 to 3 days.
• Infants, adolescents, adults, pregnant women and immunocompromised people are at risk of more severe disease and more complications.

Recovering from chickenpox usually gives lifelong immunity; a second case is uncommon in healthy people but more likely with a weakened immune system. Re-exposure to wild virus can also re-infect someone without making them ill, boosting their antibodies.

CDC. See also the varicella diagnosis fact sheet.

In vaccinated patients: breakthrough varicella

Breakthrough varicella is infection with wild-type varicella-zoster virus in someone vaccinated more than 42 days earlier. It's usually mild:

• no fever or a low one;
• fewer than 50 skin lesions;
• a shorter illness;
• a rash more often maculopapular than blistering.

But 25%–30% of people with one dose who get breakthrough chickenpox have symptoms like unvaccinated patients. Breakthrough is less common after two doses, and may be milder still, though data are limited. See the breakthrough varicella fact sheet and photos of chickenpox.

Lab confirmation is key. Because breakthrough cases are often mild, they can be hard to diagnose by appearance alone, so laboratory testing is increasingly important for confirming chickenpox and managing patients and their contacts.

Complications

The most common are bacterial skin and soft-tissue infections in children and pneumonia in adults.

Sources

Based on "Clinical Features of Chickenpox (Varicella)," Centers for Disease Control and Prevention; a work of the United States government in the public domain.