Chickenpox, caused by the Varicella-Zoster Virus, is a highly contagious illness characterized by an itchy, blister-like rash. Since the introduction of the Varicella vaccine, the incidence of this disease has dramatically declined. The vaccine works by introducing a weakened version of the virus, allowing the immune system to build defenses and successfully protect individuals from a full-blown infection.
Understanding Vaccine Efficacy and Breakthrough Cases
Yes, a vaccinated person can still get chickenpox, but the risk is low, and the resulting illness is mild. No vaccine offers 100% protection, and when an immunized person contracts the wild-type virus, it is known as a “breakthrough infection.”
A single dose of the vaccine is approximately 82% effective at preventing any form of chickenpox, while two doses increase that protection to 92% to 98% against the disease. The primary goal of vaccination is to prevent severe disease, which the vaccine is nearly 100% effective at doing. Breakthrough cases occur when the immune response generated by the vaccine is strong enough to contain the virus but not strong enough to block the infection completely upon exposure.
Recognizing Attenuated Symptoms
The symptoms experienced during a breakthrough case are less severe than in an unvaccinated person, reflecting the immune system’s partial success. A hallmark difference is the number of skin lesions; unvaccinated individuals typically develop 200 to 500 lesions, but a vaccinated person usually has fewer than 50. This attenuated form of the disease presents with an atypical rash that makes clinical diagnosis challenging.
The lesions often appear more like maculopapular spots or insect bites rather than the classic fluid-filled blisters associated with wild-type chickenpox. Fever is frequently absent or, if present, is low-grade. The course of the illness is much shorter, often resolving in just a few days compared to the week or more required for a typical infection, and the rash lesions tend to crust over and heal much faster.
Practical Steps: Contagion and Care
Even a mild breakthrough case of chickenpox is contagious and requires specific measures to prevent transmission. Since the virus spreads easily through the air and direct contact, isolation is necessary. Communicability lasts until all existing lesions have fully crusted over, or if no blisters develop, until no new lesions have appeared for a full 24-hour period.
Home care focuses on comfort and symptom management. Supportive measures include using acetaminophen for mild fever, while avoiding aspirin due to the risk of Reye’s syndrome. Calamine lotion and colloidal oatmeal baths can help relieve itching. A healthcare provider should be consulted if the rash is extensive, if the fever persists, or if there are signs of complications like severe headaches or difficulty breathing.