Chickenpox is an infectious disease that’s caused by the varicella-zoster virus (VZV). Infection with VZV causes an itchy rash that’s accompanied by fluid-filled blisters.

Chickenpox is preventable through vaccination. In fact, receiving two doses of the chickenpox vaccine is about 94 percent effective at preventing the disease.

Although you can still get chickenpox if you’ve been vaccinated, it's uncommon, and the disease is usually milder.

Read on to learn more about preventing chickenpox.

Chickenpox can be prevented through vaccination, which is recommended for:

  • all children
  • adolescents
  • adults who aren’t already immune to chickenpox

Two doses of the vaccine are needed.

Children should receive the chickenpox vaccine as part of their regular vaccine schedule. The first dose should be received between 12 and 15 months of age. The second dose should be received between 4 and 6 years of age.

Adolescents or adults who aren’t vaccinated should receive two doses of the vaccine spaced one month apart.

There are some groups who shouldn’t receive the chickenpox vaccine. They include:

  • people who’ve had a severe allergic reaction to a previous dose of the chickenpox vaccine or to one of its components
  • women who are pregnant or may be pregnant
  • individuals with a weakened immune system due to a disease or medical treatment
  • people who’ve recently received a blood or plasma transfusion
  • individuals who are currently ill with something more severe than a cold

Children and adults should avoid taking aspirin and other medications containing salicylates for six weeks after vaccination. This is because of the risk of Reye's syndrome, a rare but potentially fatal disease.

If you're already taking aspirin or other medications containing salicylates, your doctor will monitor you closely.

In addition to vaccination, you can help prevent the spread of chickenpox by practicing good hygiene and washing your hands frequently. Reduce your exposure to people who have chickenpox.

If you already have chickenpox, stay at home until all of your blisters have dried and crusted over.

Chickenpox is very contagious, meaning that it can be spread from person to person.

You can get chickenpox by making direct contact with chickenpox blisters or through the air when someone with chickenpox coughs, sneezes, or talks.

If you have chickenpox, you'll be contagious beginning one or two days before symptoms start to show. You'll remain contagious until all of your chickenpox blisters have dried out and scabbed over. This usually occurs after five to seven days.

If you've been vaccinated against chickenpox and develop a breakthrough chickenpox infection, you can still spread it to other people.

Although you may develop a milder rash that may not include blisters or be accompanied by a fever, you'll still be contagious and able to spread chickenpox until all spots have faded and no new ones have appeared after 24 hours.

Usually, once you’ve had chickenpox, you have immunity for life. However, in rare cases, some people can get chickenpox more than once.

Chickenpox and shingles

If you've had an earlier chickenpox infection, VZV will lie dormant in your nerves following your initial infection. Sometimes, VZV can reactivate later in life, causing shingles. Shingles can cause an itchy, often painful rash with fluid-filled blisters.

If you have shingles, you can pass VZV on to other people, which can lead to developing chickenpox. This can occur through direct contact with shingles blisters or through breathing in the aerosolized virus from shingles blisters.

If you have shingles, keep your rash and blisters covered to reduce the risk of spreading the virus.

Because shingles develops from a virus that's already dormant in the body, you cannot get shingles from someone who has a chickenpox infection.

It usually takes about two weeks to develop symptoms following exposure to VZV. However, in some cases, symptoms can appear in as little as 10 days or as much as three weeks.

The symptoms of chickenpox include:

  • an itchy rash with fluid-filled blisters
  • fever
  • headache
  • feeling tired or fatigued
  • loss of appetite

Sometimes you may have a fever or feelings of malaise before the rash appears.

You're no longer contagious when your chickenpox blisters have dried out and formed crusts.

Symptoms in vaccinated people

Chickenpox is usually milder and shorter in people who have been vaccinated. Symptoms may include a low fever and a milder rash that often doesn’t fully develop into blisters.

Rarely, vaccinated people can develop symptoms similar to those in an unvaccinated person.

Most people who have had chickenpox or have been vaccinated are immune to contracting the disease, even if they’re exposed to VZV.

If your child doesn't have any other underlying health conditions and develops chickenpox, they'll often only experience a mild illness that doesn't require medical treatment from a doctor.

However, always call your doctor if you notice any of the following symptoms:

  • fever that lasts longer than four days or is higher than 102°F (38.9°C)
  • a rash that becomes warm, tender to the touch, or begins leaking pus
  • frequent vomiting
  • breathing difficulties or a severe cough
  • confusion
  • issues walking
  • severe abdominal pain
  • stiff neck

You may be at an increased risk for severe complications from chickenpox if you have pneumonia and encephalitis.

Seek medical attention if you suspect chickenpox and:

  • Your child is too young to be vaccinated (younger than 12 months).
  • You're older than 12 years and haven’t had chickenpox or been vaccinated.
  • You have a weakened immune system due to a disease or medical treatment.
  • You're pregnant and haven’t had chickenpox or been vaccinated.

Antiviral medications or an injection of varicella-zoster immune globulin may be given to people who are at risk for developing severe disease from chickenpox.

Chickenpox is a contagious viral disease that causes a skin rash with blisters.

It’s often a mild disease in healthy children but can cause more severe disease or complications in groups who have a high risk, such as pregnant women, babies, and unvaccinated adolescents and adults.

Chickenpox is preventable through vaccination. All children, adolescents, and adults who aren’t immune to chickenpox should be vaccinated to prevent getting the disease.

In addition to getting vaccinated, you can help prevent the spread of chickenpox through practicing good hygiene and reducing exposure to people who have chickenpox.