Varicella Vaccine

Who is recommended to be vaccinated against Varicella?

All persons older than 1 year of age should be vaccinated with a 2-dose series. The recommended schedule is the 1st dose at 12 months and the second dose at 4-6 years of age. The minimum interval between doses is 4 weeks. For those under 13 years of age, this is increased to 3 months, unless if a second dose is needed for protection such as during a community outbreak. If a person can demonstrate evidence of immunity, they do not need to be vaccinated.

What are the potential adverse events associated with the Varicella vaccine?

As the Varicella vaccine is a live vaccine, it can cause symptoms similar to the natural vaccine. A varicella-like rash may appear. This rash is much milder than the natural version. It has fewer lesions, and the lesions are maculopapular instead of vesicular. The varicella vaccine can be transmitted to other hosts, though seemingly only in patients who develop this rash. Thus, patients who develop a rash should avoid close contact with vulnerable individuals such as infants or immunocompromised patients until the rash subsides. There is a possibility of developing herpes zoster from the varicella vaccine, though the risk is much reduced compared to the natural virus. Local injection-site reactions can also occur. Systemic symptoms are uncommon.

What are the precautions and contraindications to the Varicella vaccine?

As with all vaccines, moderate-severe acute illness with or without fever is a precaution. Also, allergic reactions to prior doses or components of the vaccine is a contraindication. Of note, the varicella vaccine does contain small amounts of neomycin and gelatin. Those with allergies to these substances should consult with an allergy specialist about receipt of this vaccine. Pregnancy is a contraindication due to a theoretical risk of teratogenicity. Receipt of a blood product in the past year (11 mo.) is a contraindication and vaccination should be deferred. The recommended interval will vary by blood product, so pharmacists should check the CDCs Epidemiology and Prevention of Vaccine-Preventables Diseases (aka PinkBook) to determine the correct interval. As the varicella vaccine is a live vaccine, immunocompromised patients should consult with their PCP about receipt of the vaccine. As the MMRV vaccine has a small increased risk of seizures, a personal or family history of seizures is a precaution to receiving the combination vaccine.

How is Varicella vaccine stored?

Because varicella vaccine is a live vaccine, it is temperature sensitive. It should be stored between -15 and -50 C (5 and -58 F) in a separate freezer unit or freezer compartment. Varicella vaccine can remain viable in a fridge for 72 hours. If not used within 72 hours, it must be discarded NOT refrozen. The vaccine's diluent can be stored in room temperature or in the fridge.

What is considered evidence of immunity to varicella, which would obviate the need for vaccination?

Documentation of appropriate vaccination Laboratory evidence of immunity Laboratory evidence of varicella infection Diagnosis of varicella or herpes zoster by a healthcare professional (self-reported or parental reporting is not sufficient) Born before 1980 (not sufficient for immunocompromised patients, healthcare providers, or women of childbearing age)

Why is the varicella vaccine not recommended for infants younger than 1 year-old?

The vaccine is a live vaccine, so circulation maternal antibodies against varicella could reduce the efficacy of the vaccine. Maternal antibodies wane over a 6-12 month period in humans.

How is Varicella vaccine administered?

The varicella must first be reconstituted with the diluent specific to the vaccine. Once reconstituted, the vaccine must be administered within 30 minutes or it must be discarded. The vaccine is given 0.5 mL SC

What are the recommendations from the ACIP regarding use of the MMRV vaccine compared to using the MMR and Varicella vaccines separately?

There is a small increased risk of seizure from the MMRV vaccine. However, the combined MMRV vaccine is still recommended if both vaccines need to be received. The exception is for children 1-3 year-olds (<4 yr old), who are recommended to get the vaccines separately for the first dose. This is just a recommendation, parents may still choose to give the MMRV vaccine.

How should varicella vaccination be handled with pregnant women or women planning to become pregnant?

There is a theoretical risk of teratogenicity from the live varicella vaccine during vulnerable stages of pregnancy. Because of this, it is recommended that women are vaccinated at least 4 weeks before pregnancy. If pregnant women are not fully vaccinated, they should complete or start their vaccination series immediately after giving birth.

What is Varicella and how serious is it?

Varicella is also known as chickenpox. It is caused by the Varicella Zoster virus. Primary infection with this virus results in Varicella. Reactivation of this virus as a secondary infection results in Herpes Zoster (aka Shingles). This virus is very contagious. Before vaccination was available, infection by the age of 15 was nearly universal. It can be transmitted through respiratory fluids or by direct contact with lesions. Varicella causes a generalized rash of several hundred to thousands of small pruritic (itchy) vesicles. These vesicles are filled with clear liquid but eventually burst or drain and then become dry crusts. The most common complication of Varicella is secondary bacterial infection of the lesions with Grade A Streptococci or Staphylococci. These infections can be serious, leading possibly to hospitalization and death. Other complications include cerebellar ataxia, encephalitis, and pneumonia. These complications are more common and serious in the following populations: adults, children older than 1 year, immunocompromised patients, and newborns of varicella-infected mothers.

What vaccines are available for Varicella?

Varicella vaccine is a live-attenuated vaccine. It is available as a single-component vaccine (Varivax) or in combination with MMR (as MMRV).