Varicella-zoster is a preventable virus that is responsible for a common childhood ailment: the chickenpox.


5 - 8


Biology, Health



This photomicrograph shows some of the changes visible in human tissue infected with the varicella zoster virus.

Photograph by the Centers for Disease Control and Prevention
This photomicrograph shows some of the changes visible in human tissue infected with the varicella zoster virus.

Varicella-zoster virus, the virus responsible for causing chickenpox, is infamous in part because it is highly transmissible. Today, however, chickenpox is much less common in the United States than it once was.

The varicella virus spreads via particles transmitted through the air, as well as through skin-to-skin contact. Around two days after exposure, blisters begin to form. In addition to these blister-like rashes, the infected person begins itching. Other symptoms include fatigue and fever. Although the symptoms are uncomfortable, chickenpox is generally not life threatening. However, chickenpox can present a more serious threat to babies, pregnant women, and people with weakened immune systems. In rare cases, chickenpox can cause major complications, such as pneumonia.

Chicken pox is not as common in the United States as it used to be. Chickenpox used to cause about 4 million cases each year. Now, thanks to the chickenpox vaccine, which is approximately 90 percent effective in preventing chickenpox after two doses, the disease is much less common.

The chickenpox vaccine was first used in the United States in 1995. Since 2006, the Centers for Disease Control and Prevention (CDC) has recommended children receive two doses of the vaccine: one at twelve to fifteen months and the other at four to six years. This vaccine is available on its own or in combination with the measles mumps rubella (MMR) vaccine. While the chickenpox vaccine is highly effective in protecting individuals and communities, you can still get chicken pox if you have been vaccinated, but symptoms will likely be much milder than those experienced by someone who has not been vaccinated.

The varicella virus can be treated with an antiviral known as acyclovir, but since cases are often mild, it is preferable to allow chickenpox to simply run its course. The symptoms, particularly itching, can be alleviated with home treatments, including calamine lotion and oatmeal baths. Relieving itching is especially important so that the infected person does not cut the blisters, which could lead to an infection and allow the virus to spread more readily.

The varicella virus does not only cause chickenpox; it can reactivate later in life and lead to shingles, which causes a painful skin rash and affects the nervous system. Someone with shingles can still spread the varicella virus, but the person they infect will develop chickenpox, not shingles. Like chickenpox, shingles is common, affecting one-third of the U.S. population at some point in their lives.

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Tyson Brown, National Geographic Society
National Geographic Society
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Last Updated

October 19, 2023

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