Varicella-zoster virus (VZV) is the virus that causes chickenpox and shingles. It is a member of the herpes virus group. VZV is very contagious and causes a red, itchy rash. It also leads to blisters that crust over within a few days.

Once the symptoms of chickenpox resolve, the virus stays in your body in a latent state—meaning the virus is alive but does not cause symptoms. This latent virus may later cause shingles (herpes zoster virus) if reactivated. Fortunately, you can prevent the varicella-zoster virus with a vaccine. 

The varicella-zoster virus causes chickenpox. The main symptom is a red, itchy rash. This rash typically starts on the chest, back, and face and then spreads to other body parts.

Other symptoms of varicella-zoster may include:

• Malaise: Generally not feeling well
• Fever: Up to 102 degrees Fahrenheit (38.9 degrees Celsius) for three days 

Chickenpox symptoms usually last about 4-7 days. Once you recover from chickenpox, you are immune to the virus. However, the varicella-zoster virus lives in your body and can reactivate as shingles in the future. 

The varicella-zoster virus infects the body when you are exposed to it by someone already infected. This virus is highly contagious and easily spreads through communities that are not immune to it. The Centers for Disease Control and Prevention (CDC) estimates that when a person has chickenpox, about 90% of their unvaccinated household members will also get it. 

Varicella-zoster spreads through direct contact and inhalation. If you are around a person who has chickenpox, you could catch the virus by touching their rash or breathing in the same air. Chickenpox is contagious until you have no new rash lesions for at least 24 hours. 

Varicella-zoster virus takes about 10-21 days to develop after exposure. If you are exposed to chickenpox, you may not develop symptoms for 2-3 weeks. 

Getting the vaccine can help prevent you from getting chickenpox. While it is still possible to get chickenpox after getting the vaccine, it is much less likely. If a vaccinated person does get chickenpox, the virus is usually much less severe.

Your healthcare provider typically diagnoses varicella-zoster virus based on its symptoms. Chickenpox causes a red, itchy, blister-like rash. Shingles cause a painful, blister-like rash that appears on the side of the torso. 

It is possible to determine if you are immune to VZV with a blood test. Your healthcare provider can test your blood for antibodies to the virus using a polymerase chain reaction (PCR) blood test.

The goal of varicella-zoster treatment is to improve the symptoms and shorten the time of illness. The varicella-zoster virus lives in your body after you recover from chickenpox and is incurable. It can still reactivate as shingles in the future. 

Healthy children who contract chickenpox do not usually require treatment beyond rest. People at a high risk of developing severe disease may need medical treatment. 

People in the high-risk group include:

• Adolescents and adults over 12 years old
• People with a compromised immune system 
• Those with chronic pulmonary (lung) problems 
• People taking long-term aspirin treatment
• Pregnant people 
• People taking corticosteroids regularly, as these medications can suppress your body’s natural immune response
• Young infants who have not been vaccinated yet 

Varicella-Zoster Immune Globulin

People who are unvaccinated and considered high-risk for severe disease may benefit from taking a medication called varicella-zoster immune globulin (VZIG). This treatment can prevent varicella-zoster from causing chickenpox after exposure.

Varicella-zoster immune globulin, which goes by the brand name VariZIG, can be given up to 10 days after exposure to the illness. It is used in people who are unvaccinated and cannot receive the vaccine for medical reasons. 

Acyclovir 

Zovirax (acyclovir) is an antiviral medication that can prevent severe disease in unvaccinated people if taken within the first 24 hours of symptoms. Your healthcare provider may recommend acyclovir if you are in the high-risk group or have developed serious complications such as pneumonia.

Acyclovir may not be safe for pregnant people. Your healthcare provider can help you determine if it’s the right fit for you. 

While varicella-zoster virus is a serious infection that can cause severe symptoms in certain people, the virus is preventable with a safe and effective vaccine. 

Chickenpox was a common infection in the United States until the vaccine became available. The CDC estimates that about 4 million people became ill with chickenpox in the early 1990s. Once the vaccine became available in 1995, cases dropped by 97%. For people under 20 years old, hospitalizations dropped by 97%, and deaths decreased by 99%. 

Two doses of the varicella vaccine are recommended for most healthy children. Children with a compromised immune system should not receive the varicella vaccine. The two varicella vaccines available in the U.S. include:

• Varivax: Chickenpox vaccine available for those 12 months and older
• ProQuad: A combination of the measles, mumps, rubella (MMR) vaccine and the varicella vaccine for children 12 months to 12 years 

Most healthy children who contract chickenpox recover on their own without issues. Certain groups are at high risk of developing serious complications from the varicella-zoster virus. Pregnant people, older people, young infants, and anyone with a suppressed immune system are at risk of complications. 

Chickenpox is especially dangerous for pregnant people and their babies. The babies of people with chickenpox during pregnancy may develop congenital varicella, a syndrome that causes abnormal development of the brain, eyes, and skin.

Shingles

Varicella-zoster virus can remain dormant in your body for years after initial infection. The virus can reactivate later in life in those who have had chickenpox, leading to shingles (herpes zoster). Reactivation typically occurs when your immune system is weak, which can occur due to aging, stress, or immunosuppressive conditions.

Shingles manifests as a painful rash, often appearing on one side of the body or face. It is characterized by clusters of blisters that follow the path of affected nerves.

The reactivation of VZV can cause nerve inflammation, leading to sharp pain even after the rash subsides—a condition known as postherpetic neuralgia. Postherpetic neuralgia can last from days to years, depending on a person’s age and overall health. 

Skin Infections

Children and adults may develop a bacterial skin infection following chickenpox due to scratching, which can expose the skin to bacteria and infection. 

A bacterial infection of the skin may lead to:

• Septicemia: Blood infection
• Toxic shock syndrome: Bacterial infection in the blood
• Necrotizing fasciitis: Skin infection that leads to tissue death
• Osteomyelitis: Bone infection
• Bacterial pneumonia: Lung infection
• Septic arthritis: Infection in the joints

Other Possible Complications

Adults who contract chickenpox are at risk of developing:

• Viral pneumonia: Lung infection 
• Cerebellar ataxia: Lack of muscle control
• Encephalitis: Infection and swelling in the brain
• Vasculopathy: Infection in the arteries
• Neuralgia: Pain after the rash heals
• Guillain-Barré syndrome: Occurs when the immune system attacks the nervous system

Varicella-zoster virus is the virus that causes chickenpox and is a member of the herpes virus group. This virus is preventable in young people with a two-dose vaccine. Symptoms of chickenpox include fever, malaise, and a red, itchy, blister-like rash. Shingles usually presents as a painful rash that blisters and crusts over. 

People who have recovered from chickenpox may later develop shingles because the varicella-zoster virus lives in the body and cannot be fully cured.