Chickenpox, caused by the highly contagious Varicella-Zoster Virus (VZV), is commonly viewed as a benign childhood illness. This airborne virus spreads easily through respiratory droplets and direct contact, leading to a characteristic rash of itchy, fluid-filled blisters. While the infection is typically mild in children, the implications of never acquiring immunity extend far beyond childhood. For non-immune adolescents and adults, contracting VZV later in life carries a significantly heightened risk of severe complications, hospitalization, and even death. The absence of immunity necessitates proactive steps for assessment and prevention.
Assessing Your Immunity Status
If you are uncertain about your childhood history, medical professionals can definitively determine your immune status using a simple blood test called a VZV serology test. This test measures the presence of Varicella-Zoster Virus immunoglobulin G (IgG) antibodies in your bloodstream. A positive IgG result indicates that your body has previously encountered the virus, either through natural infection or vaccination, and has developed protective immunity.
A negative test result confirms that you are susceptible to the virus, meaning your body has no pre-existing defense against VZV. This confirmation of non-immunity should prompt a discussion with a healthcare provider about immediate preventative action. While commercial tests effectively detect antibodies from a prior natural infection, they may not always detect the lower antibody levels induced by the vaccine. Regardless, a documented history of two vaccine doses or a positive antibody test is generally accepted as evidence of immunity.
Increased Severity of Adult Infection
The most significant risk for non-immune individuals is the substantially increased severity of the disease when contracted in adulthood. While children usually experience a week of discomfort, adults often face a more prolonged illness with a higher frequency of serious complications. The flu-like symptoms that precede the rash, such as fever and malaise, are typically more pronounced and last longer. Furthermore, the characteristic vesicular rash may be more widespread, covering the body more densely.
Viral pneumonia is the most common serious complication in adults, occurring in up to 90% of all varicella pneumonia cases. This condition can lead to acute respiratory distress and requires immediate hospitalization. Other severe consequences include encephalitis, which is inflammation of the brain that can cause permanent neurological damage or death. Secondary bacterial infections of the skin lesions are also more common, potentially leading to toxic shock syndrome or sepsis.
Prevention Through Vaccination
The most effective strategy to avoid the severe consequences of adult chickenpox is vaccination. The Varicella vaccine is a live-attenuated vaccine that safely introduces a weakened form of the virus to stimulate an immune response without causing the disease. For all non-immune adolescents and adults, a two-dose series is the standard recommendation for achieving robust, long-lasting protection. The second dose is necessary to maximize the immune response, as a single dose may only be about 82% effective.
The two doses should be administered subcutaneously, separated by a minimum interval of four to eight weeks, depending on the recipient’s age. This full two-dose schedule is highly effective, offering protection against all forms of the disease in the range of 92% to 98%. If a non-immune person is exposed to VZV, the vaccine can still be administered as Post-Exposure Prophylaxis (PEP) within three to five days of exposure to help prevent or lessen the severity of the illness. In certain high-risk situations, Varicella-Zoster Immune Globulin (VZIG) may be used for immediate, temporary protection.
High-Risk Scenarios
For certain populations, the risk posed by VZV infection is significantly elevated, extending beyond the individual. Non-immune pregnant individuals face unique dangers, as VZV infection can harm both the mother and the developing fetus. Pregnant people who contract chickenpox have a greater risk of developing severe viral pneumonia compared to non-pregnant adults.
Infection during the first 20 weeks of gestation carries a small, serious risk of causing Congenital Varicella Syndrome in the fetus, resulting in birth defects affecting the limbs, eyes, and brain. The Varicella vaccine cannot be administered during pregnancy because it contains a live virus, meaning non-immune women must be vaccinated before conception. Infection occurring around the time of delivery can also lead to life-threatening neonatal varicella in the newborn. Immunocompromised individuals, such as those undergoing chemotherapy, also face a higher likelihood of disseminated infection, which spreads throughout the body and can be fatal.