Varicella, also known as chickenpox, is a highly contagious illness caused by the varicella-zoster virus (VZV), a member of the herpesvirus family. It causes an itchy skin rash with red spots and small fluid-filled blisters that eventually dry out and form scabs. The rash usually starts on the face, chest, and back before spreading to other parts of the body, including the scalp, arms, legs, and sometimes inside the mouth or nose. While chickenpox is most common in children, people of any age can get it, and it is often more severe in teenagers, adults, pregnant women, and people with weakened immune systems.
The virus spreads easily through direct contact with the rash or through the air when an infected person coughs or sneezes. Once exposed, it usually takes 10 to 21 days before symptoms appear. Early signs can include mild fever, tiredness, loss of appetite, and general discomfort, followed by the rash. The spots appear in stages—starting as flat red marks, then raised bumps, then blisters, and finally scabs. It is common for spots in different stages to appear at the same time.
In healthy children, chickenpox usually goes away on its own within 1–2 weeks. However, complications can occur, such as skin infections, pneumonia, swelling of the brain (encephalitis), liver inflammation (hepatitis), or, in rare cases, death. These risks are higher for newborns, unvaccinated adults, pregnant women, and people with weak immune systems. In pregnancy, infection can sometimes harm the baby, causing congenital varicella syndrome or severe newborn illness.
The introduction of the chickenpox vaccine has greatly reduced the number of cases, the severity of illness, and deaths in many countries. Vaccination is the best way to prevent infection and also reduces the risk of the virus reactivating later in life as shingles.
Treatment for most healthy people focuses on relieving symptoms, such as reducing fever and easing itching. People at higher risk of severe illness may be given antiviral medicines like acyclovir or valacyclovir, especially if treatment starts within 24 hours of the rash appearing.
Signs and Symptoms
Varicella infection is characterized by a sequence of specific clinical signs. Early symptoms include general discomfort before the appearance of skin changes. The rash evolves in distinct stages, and fever often occurs alongside skin manifestations.
Early Manifestations
The initial phase, known as the prodromal stage, typically occurs one to two days before the rash appears. Early symptoms may include malaise (a general feeling of discomfort), headache, mild fever, loss of appetite, and fatigue. In some cases, mild skin itching begins before visible spots appear, usually affecting the torso and face first. Lymphadenopathy (swelling and tenderness of lymph nodes) may occur, particularly in the neck or behind the ears. Because these early symptoms are nonspecific, the illness may be mistaken for another viral infection until the rash develops.
Progression of Rash
The rash generally begins as small red spots (macules) that rapidly progress to raised bumps (papules) and then to small, fluid-filled blisters (vesicles). These lesions appear in successive “crops” over several days, meaning that new spots form while older ones burst, dry, and develop crusts. This results in lesions at different stages of development—macules, papules, vesicles, and crusts—being present at the same time, a clinical hallmark of varicella. The rash usually starts on the face and trunk before spreading to the scalp, arms, legs, and sometimes the mucous membranes of the mouth, eyelids, or genitals. Itching is often intense and can worsen as more lesions appear.
Associated Fever
Fever may develop just before or during the onset of the rash, typically ranging from 38°C to 39.5°C (100.4°F to 103.1°F). In otherwise healthy children, the fever is usually mild to moderate, but in adolescents and adults it may be higher and last longer. The fever often fluctuates during the course of the illness and generally subsides once most lesions have crusted over. In severe cases, prolonged fever may indicate complications such as secondary bacterial infections or pneumonia.
Transmission and Risk Factors
Varicella is primarily spread through airborne particles and direct contact. Certain groups are more likely to experience severe illness or complications.
Modes of Transmission
The varicella-zoster virus (VZV) spreads primarily through respiratory droplets released when an infected person coughs, sneezes, or talks. The virus can also spread by direct contact with the fluid inside chickenpox blisters, which contains high concentrations of viral particles. Transmission can occur 1–2 days before the rash appears during the prodromal stage and continues until all blisters have dried and crusted over, usually 5–7 days after rash onset.
Although transmission via contaminated objects (fomites) such as bedding, clothing, or utensils is possible, it is considered a minor route of spread compared to airborne and direct contact transmission. VZV is relatively fragile outside the human body and does not survive for long on surfaces.
Close and prolonged contact significantly increases the likelihood of infection. Outbreaks are most common in crowded settings such as schools, daycare centers, and households where individuals share close living spaces. In healthcare environments, airborne transmission can occur over distances, leading to rapid spread among susceptible patients and staff if infection control measures are not in place.
High-Risk Populations
While varicella is generally mild in healthy children, certain groups face a significantly higher risk of severe disease and complications, including:
- Infants, especially those younger than 12 months who are too young for routine vaccination.
- Pregnant women, for whom infection can lead to congenital varicella syndrome in the fetus or severe illness in the newborn.
- Immunocompromised individuals, such as those undergoing chemotherapy, taking long-term corticosteroids, or living with HIV/AIDS, who are more susceptible to pneumonia, hepatitis, encephalitis, and disseminated varicella.
- Unvaccinated adults, particularly those who have never had chickenpox, as they are more likely to experience severe symptoms and complications compared to children.
- Healthcare workers and caregivers, who have frequent exposure to infected individuals and may contribute to nosocomial (hospital-acquired) transmission.
Vaccination greatly reduces the risk of infection in these populations and, if breakthrough infections occur, they are generally milder and of shorter duration.
Diagnosis of Varicella
Accurate diagnosis of varicella is essential for timely management and infection control. This process depends on recognizing clinical symptoms and confirming with laboratory tests when needed.
Clinical Evaluation
The diagnosis of varicella is most often made by recognizing its characteristic rash in combination with relevant history and associated symptoms. The rash typically begins as small, flat red spots (macules) that quickly develop into raised bumps (papules) and then into small, fluid-filled blisters (vesicles) containing clear fluid. These lesions usually appear in successive crops over several days, resulting in spots at different stages of development present at the same time.
The distribution of the rash often starts on the face, chest, and back, then spreads to the scalp, arms, and legs, and in some cases to mucous membranes such as the mouth or genital area. Itching is common and may be severe.
Other associated symptoms include low-grade fever, malaise (general discomfort), headache, and loss of appetite. These may occur 1–2 days before the rash develops. A recent history of close contact with a person who has chickenpox or shingles strongly supports the diagnosis.
Physical examination focuses on lesion morphology (appearance) and distribution pattern, which help distinguish varicella from other conditions that cause rashes, such as herpes zoster (shingles), hand, foot, and mouth disease, insect bites, or allergic skin reactions.
Laboratory Techniques
Laboratory confirmation is needed when the clinical presentation is atypical or in immunocompromised patients. Polymerase chain reaction (PCR) testing of lesion samples is the gold standard due to its high sensitivity and specificity.
Direct fluorescent antibody (DFA) testing is another option, providing rapid results but with lower sensitivity than PCR.
Serologic testing for varicella-zoster virus (VZV) IgM and IgG can assist in identifying recent or past infection, particularly in pregnant women or those with unknown immunity.
Viral culture is less commonly used as it takes longer and has reduced sensitivity compared to molecular methods.
Complications Associated With Chickenpox
Chickenpox can lead to several serious health issues beyond the initial rash and fever. These complications often require medical attention and may result in long-term effects.
Secondary Infections
The most frequent complication of chickenpox is secondary bacterial infection of the skin lesions. This occurs when blisters are scratched or broken, allowing bacteria—most often Staphylococcus aureus or Streptococcus pyogenes—to enter. Such infections may cause:
- Cellulitis – a painful infection of the deeper layers of skin.
- Impetigo – a contagious superficial skin infection producing honey-colored crusts.
- Abscesses – localized collections of pus.
In severe cases, untreated bacterial infections can progress to sepsis (a life-threatening bloodstream infection) or necrotizing fasciitis (a rapidly spreading infection that destroys skin, muscle, and other tissues). Preventive measures include keeping the skin clean, trimming fingernails, and avoiding scratching. Antibiotic therapy is required if bacterial infection develops. Immunocompromised individuals and those with chronic skin conditions such as eczema have a higher risk of serious secondary infections.
Neurological Complications
Although rare, neurological complications of varicella can be severe and potentially life-threatening. These include:
- Encephalitis – inflammation of the brain, presenting with symptoms such as headache, confusion, seizures, or loss of consciousness.
- Cerebellar ataxia – affecting balance and coordination, usually temporary but sometimes prolonged.
- Guillain–Barré syndrome – an autoimmune disorder causing progressive muscle weakness and, in severe cases, paralysis.
- Reye’s syndrome – a rare but serious condition involving swelling of the brain and liver, most often associated with the use of aspirin in children or teenagers during viral illnesses, including chickenpox.
These complications typically require hospitalization and specialized treatment, with recovery depending on early detection and medical intervention.
Risks During Pregnancy
Chickenpox infection during pregnancy can harm both the mother and fetus. Early pregnancy exposure risks congenital varicella syndrome, which includes limb deformities, skin scarring, and eye abnormalities.
Infections in late pregnancy (within five days before or two days after delivery) increase the chances of neonatal varicella, a severe and sometimes fatal condition in newborns due to their immature immune systems.
Pregnant women exposed to varicella who lack immunity may be given varicella-zoster immune globulin (VZIG) to reduce the severity of the illness. Because the varicella vaccine contains a live attenuated virus, it is not recommended during pregnancy, but vaccination before conception is advised to prevent complications.
Treatment and Management
Effective management of varicella involves symptom relief, infection control, and careful monitoring for complications. Treatment focuses on minimizing discomfort and preventing secondary infections through both self-care and medical intervention.
Home Care Guidelines
For otherwise healthy individuals, supportive care is the mainstay of treatment. Key measures include:
- Hygiene – Daily lukewarm baths help keep the skin clean and reduce itching. Mild, fragrance-free soap is recommended to avoid further skin irritation.
- Itch relief – Cool compresses, calamine lotion, and oatmeal baths may help soothe itching. Keeping fingernails short and clean helps prevent skin damage from scratching, which can lead to secondary bacterial infections.
- General care – Adequate hydration, rest, and a balanced diet support immune function during recovery.
- Isolation – Infected individuals should remain at home and avoid close contact with others, particularly unvaccinated people, pregnant women, newborns, and immunocompromised individuals, until all lesions have crusted over.
Pharmacological Interventions
- Antiviral medications – Drugs such as acyclovir, valacyclovir, or famciclovir are most effective when started within 24 hours of rash onset. They can shorten illness duration and reduce symptom severity, particularly in high-risk groups such as adolescents, adults, pregnant women, and immunocompromised patients.
- Fever and pain management – Over-the-counter analgesics such as acetaminophen (paracetamol) can relieve fever and discomfort. Aspirin should be avoided in children and teenagers due to the risk of Reye’s syndrome, a rare but serious condition affecting the brain and liver.
- Itch management – Oral or topical antihistamines may be prescribed for persistent itching.
- Antibiotics – Only indicated if secondary bacterial infections, such as cellulitis or impetigo, develop.
Prevention of Disease Spread
Varicella is contagious from 1–2 days before the rash appears until all blisters have crusted, which typically occurs 5–7 days after symptoms begin. The virus spreads primarily through respiratory droplets released when an infected person coughs or sneezes, as well as through direct contact with the fluid from chickenpox blisters. Because of its high transmissibility, preventive measures are essential to reduce the risk of infection, especially in high-risk settings such as households, schools, and healthcare environments.
Isolation is a key preventive strategy, requiring infected individuals to avoid contact with non-immune persons during the contagious period. Good hygiene practices, including frequent handwashing and the use of masks when around others, further reduce the likelihood of transmission. Vaccination remains the most effective method of prevention, significantly lowering the risk of contracting the disease, as well as reducing the severity of illness and potential complications in breakthrough cases.
For high-risk individuals without immunity such as pregnant women, newborns, and immunocompromised persons—post-exposure prophylaxis may be necessary. In these cases, varicella-zoster immune globulin (VZIG) can be administered within 10 days of exposure to help reduce the severity of the disease. This targeted intervention, combined with isolation, hygiene measures, and vaccination, forms a comprehensive approach to controlling varicella spread.
Varicella Vaccination
The varicella vaccine is essential for preventing chickenpox and reducing complications. Different vaccine types are available, with specific schedules recommended based on age and health status. The vaccine’s safety and efficacy have been extensively studied, confirming its role in controlling varicella outbreaks.
Vaccine Types
Two main types of varicella vaccines exist: monovalent and combination vaccines. The monovalent vaccine contains only the varicella virus. Combination vaccines, such as MMRV, include protection against measles, mumps, rubella, and varicella.
Both types use a live attenuated virus to stimulate immunity. They are administered subcutaneously. The choice between monovalent and combination vaccines depends on patient age, previous vaccination history, and clinical guidelines.
Vaccination Schedules
The Advisory Committee on Immunization Practices (ACIP) recommends two doses for children. The first dose is given at 12 to 15 months, and the second at 4 to 6 years of age. For unvaccinated older children, adolescents, and adults, two doses should be given at least 4 to 8 weeks apart.
Immunocompromised individuals may require specific considerations and consultation with specialists. Pregnant women should avoid vaccination during pregnancy and be vaccinated postpartum if needed.
Efficacy and Safety
The varicella vaccine is about 90% effective at preventing any form of chickenpox. It is more effective at preventing severe disease. Breakthrough varicella cases can occur but are usually mild.
Common side effects are mild and include pain or redness at the injection site, fever, and mild rash. Serious adverse reactions are rare. The vaccine has a strong safety profile backed by extensive post-licensure monitoring.
Prevention Strategies Beyond Vaccination
Effective prevention of varicella extends beyond vaccination by incorporating targeted infection control practices and timely medical interventions after exposure. These methods help reduce transmission and mitigate the severity of the disease, especially in high-risk populations.
Infection Control Measures
Strict hygiene and patient isolation are essential for limiting varicella spread. Infected individuals should remain in isolation until all skin lesions have crusted over, a process that generally takes 5–7 days after rash onset. During this period, exclusion from schools, workplaces, and public gatherings is recommended.
Frequent handwashing with soap and water is necessary, especially after contact with vesicular fluid or respiratory secretions. Surfaces and objects contaminated by the infected person should be cleaned and disinfected using appropriate virucidal agents.
In healthcare settings, additional airborne and contact precautions are required. Healthcare workers should use personal protective equipment (PPE), including gloves, gowns, and N95 respirators (or equivalent), when caring for patients. Airborne isolation rooms are recommended for hospitalized varicella cases to prevent virus spread via aerosolized respiratory droplets.
Limiting contact between infected individuals and susceptible persons, particularly immunocompromised individuals, pregnant women, and unvaccinated children, significantly reduces the risk of severe outcomes.
Post-Exposure Prophylaxis
Post-exposure prophylaxis (PEP) is intended to prevent or attenuate varicella symptoms in individuals who have been exposed to the virus but are not yet symptomatic. The recommended interventions vary depending on the exposed person’s immune status and health condition.
Varicella-zoster immune globulin (VZIG) is advised for unvaccinated individuals at high risk of severe disease, such as those who are immunocompromised, pregnant women without evidence of immunity, and certain newborns. VZIG is most effective when administered within 96 hours of exposure, although it may still offer some benefit if given up to 10 days after exposure.
Antiviral therapy, such as acyclovir or valacyclovir, may be prescribed for healthy individuals at increased risk of complications (e.g., adolescents, adults, or those with chronic skin or lung conditions) if initiated within 7–10 days after exposure. Early administration can reduce the severity and duration of illness.
Close monitoring of exposed persons for early signs of infection—such as fever or rash—allows for timely medical intervention. In outbreak situations, public health authorities may recommend targeted isolation, vaccination of susceptible contacts, and enhanced surveillance to control disease spread.
Prognosis and Long-Term Outcomes
Varicella generally resolves without major complications in healthy individuals, but the recovery process and risks of recurrence vary. Long-term effects depend largely on age, immune status, and the presence of complications during the acute phase.
Recovery Expectations
Recovery from varicella typically occurs within two weeks after the onset of the rash. The skin lesions progress through stages of red spots, blisters, crusting, and healing. Most individuals experience mild fatigue and itching during this time.
Complications such as bacterial infections of the skin or pneumonia may extend recovery or require medical intervention. In immunocompromised patients or adults, recovery may be slower and associated with greater risk of severe outcomes.
After the active infection resolves, patients often experience immune memory that helps protect against severe illness from future exposures. However, the healing skin may leave temporary or permanently pigmented scars in some cases.
Potential for Recurrence
Varicella itself does not recur after the initial infection because the body develops immunity to the virus. However, the varicella-zoster virus remains dormant in nerve cells.
Later in life, the virus can reactivate as herpes zoster (shingles), particularly in older adults or those with weakened immune systems. This reactivation presents as a painful rash localized to a nerve segment and differs clinically from primary varicella.
Vaccination reduces the risk of both initial varicella and subsequent shingles but does not eliminate the possibility of shingles entirely. The likelihood of reactivation depends on individual immune status rather than prior severity of chickenpox.
Varicella in Special Populations
Certain groups face greater risks or require different management when affected by varicella. These populations often experience more severe disease, complications, or specific precautions related to treatment and prevention.
Infants and Young Children
Infants under one year old, particularly those younger than 6 months, are vulnerable to varicella because maternal antibodies wane early, providing limited protection. The disease in this group can lead to serious complications such as bacterial superinfections, pneumonia, or encephalitis.
Young children typically exhibit milder symptoms than adults; however, healthcare providers monitor them closely due to their immature immune systems. Vaccination is recommended for children older than 12 months to reduce the incidence and severity of varicella.
Hospitalization rates are higher in infants with varicella, emphasizing the need for early identification and supportive care to manage dehydration and secondary infections.
Immunocompromised Individuals
People with weakened immune systems—due to conditions like HIV, cancer, or immunosuppressive therapies—face a higher risk of severe varicella. The infection can progress rapidly, causing disseminated disease, pneumonia, hepatitis, or neurological complications.
Antiviral therapy, such as acyclovir, is critical for immunocompromised patients as it reduces viral replication and decreases complication rates. Vaccination with a live attenuated virus is generally contraindicated, except under strict medical supervision in select cases.
Close monitoring and early treatment are essential. In some cases, intravenous antiviral drugs and hospitalization are required due to the increased risk of severe outcomes.
Pregnant Women
Varicella during pregnancy poses significant risks to both the mother and fetus. Maternal varicella pneumonia is a serious complication that raises morbidity and mortality rates.
Infection during the first 20 weeks of gestation can result in congenital varicella syndrome, which causes limb abnormalities, neurological defects, and skin scarring. Varicella infection near delivery increases the risk of neonatal varicella, which can be life-threatening.
Pregnant women who lack immunity to varicella should avoid exposure. Post-exposure prophylaxis with varicella-zoster immune globulin (VZIG) is recommended if exposure occurs. Antiviral treatment may be considered depending on disease severity and pregnancy stage.
Historical and Epidemiological Perspective
Varicella (chickenpox) has historically been a widespread infectious disease, with epidemiological patterns varying according to geographic, climatic, and socioeconomic factors. Before the advent of routine vaccination programs, varicella was considered an almost universal childhood illness.
In temperate climates, the majority of individuals contracted the disease by adolescence, with peak incidence occurring in late winter and spring. In tropical regions, childhood infection rates were lower, and a greater proportion of cases occurred in adolescents and adults, who are at higher risk of severe complications such as pneumonia, encephalitis, and secondary bacterial infections.
Prior to vaccination, outbreaks were common in schools, childcare facilities, and institutional settings, where close contact facilitated transmission. Although varicella-related mortality was relatively low in the general population, fatal outcomes were more frequent among immunocompromised individuals, newborns, and unvaccinated adults.
The introduction of the varicella vaccine in the mid-1990s marked a turning point in disease epidemiology. In countries with widespread vaccine coverage, incidence rates declined by approximately 70–90% within a decade. Hospitalizations, severe cases, and mortality rates also decreased significantly. The benefits extended to unvaccinated individuals through herd immunity, particularly protecting populations unable to receive the vaccine for medical reasons.
Some nations, including the United States, Australia, and Germany, adopted a two-dose vaccination schedule to address breakthrough infections—cases of varicella occurring in vaccinated individuals—further reducing both incidence and outbreak frequency.
| Key Outcomes of Vaccination | Observed Effects |
| Incidence Reduction | 70-90% decrease in reported cases |
| Hospitalization Rates | Significant decline |
| Complication Frequency | Reduced, especially in children |
| Herd Immunity | Protection of unvaccinated groups |