Varivax chickenpox vaccine

Varivax Vaccine (Chickenpox)

Varivax is a vaccine against chickenpox (varicella) that is made by Merck & Co. The most common long-term complication is the virus re-activating and causing shingles in adults.

What is Varivax?

Varivax vaccine injection shot bottles vialsVarivax® (Varicella Virus Vaccine Live) is an immunization against chickenpox. It is approved for the prevention of chickenpox (varicella) in individuals 12 months of age and older. Each dose is approximately 0.5 mL and it is administered in a single-dose injection.

Who makes Varivax?

Varivax is manufactured by Merck & Co. at a facility in West Point, Pennsylvania.

When was Varivax approved?

Varivax was approved by the U.S. Food and Drug Administration (FDA) in March 1995.

How many doses do I need?

The vaccination schedule is as follows: children 12 months to 12 years old need their 1st dose at age 12-15 months, and a 2nd dose at 4-6 years old. There should be a minimum interval of 3 months between doses.

Teenagers over age 13 and adults need two doses of Varivax, to be administered at least 4 weeks apart.

Do I need a booster shot?

Yes. In June 2006, the U.S. Centers for Disease Control (CDC) began recommending a 2nd dose of Varivax to boost immunity in children and adults.

How effective is Varivax?

Varivax is not effective in 15-20% of children who only get one dose. This is why the government recommends two doses to strengthen immunity. No one knows how long Varivax is effective. Over time, the virus naturally evolves immunity and vaccines become less effective.

Who should not get Varivax?

Do not get Varivax if you or your child:

  • Are allergic to any ingredients, gelatin, or neomycin (see below for a list of ingredients in Varivax)
  • Have a moderate or severe illness
  • Have a weakened immune system, leukemia, lymphoma, or HIV/AIDS
  • Take high doses of steroids by mouth or in a shot
  • Have active tuberculosis
  • Have a fever
  • Are pregnant or plan to get pregnant in the next 3 months

What are the possible side effects of Varivax?

Once you are vaccinated with Varivax, the virus stays in your body forever. In about 33% of adults, it re-activates and causes shingles, a painful rash that frequently causes nerve damage and chronic pain.

The most common side effects of Varivax are fever, irritability, chickenpox-like rash, and complications where the shot was given (pain, swelling, itching, or redness).

Fevers occur in 10-15% of people who get Varivax, but do NOT use aspirin to treat fever or pain. This can cause Reye’s Syndrome, a serious condition involving liver damage or permanent brain damage.

Varivax can cause serious chickenpox infections. Very rare side effects include allergic reactions, eye damage, bleeding disorders, low blood count (anemia), difficulty walking, severe skin problems, skin infections, swelling of the brain, stroke, inflammation of the lungs (pneumonia), organ damage, and seizures with or without a fever.

Does Varivax have a live virus?

Yes. Varivax has a live attenuated varicella-zoster virus (VSV), which means it contains a weakened virus that causes chickenpox. This virus causes a mild infection that triggers the body to respond and develop immunity.

What else is in Varivax?

  • sucrose
  • phosphate
  • glutamate
  • gelatin
  • monosodium L-glutamate (MSG)
  • sodium phosphate dibasic
  • potassium phosphate monobasic
  • potassium chloride
  • sodium phosphate monobasic
  • potassium chloride
  • EDTA
  • residual components of MRC-5 cells including DNA and protein
  • neomycin
  • fetal bovine serum
  • human diploid cell cultures (WI-38)
  • embryonic guinea pig cell cultures
  • human embryonic lung cultures

Who created the chickenpox vaccine?

Dr. Michiaki Takahashiat invented the first chickenpox vaccine at the Biken Institute in Osaka, Japan in 1974. He created it using a wild-type Oka strain of the varicella-zoster virus (VZV) that was isolated from a child with chickenpox.

To learn more about the side effects associated with the chickenpox and/or Varivax vaccine, please visit this page: Chickenpox Vaccine Side Effects

Where can I get more information?

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