VAR

Varicella (Chickenpox) Vaccine

Content reviewed against published CDC, AAP, WHO guidelines

Editorial policy

Last reviewed:

Key takeaways

  • Prevents: Varicella (chickenpox), Complications of chickenpox (bacterial skin infections, pneumonia, encephalitis)
  • Schedule: 2 doses starting at 12-15 months
  • Effectiveness: One dose is 85% effective at preventing any chickenpox and 97-100% effective at preventing severe chickenpox.
  • Most common side effect: Soreness, redness, or swelling at injection site

How it works

The varicella vaccine contains a live, attenuated (weakened) strain of varicella-zoster virus (the Oka strain). This weakened virus replicates enough to stimulate a strong immune response — including both antibodies and cellular immunity — but is too weak to cause full-blown chickenpox. After vaccination, the immune system develops memory cells that can rapidly respond if exposed to wild varicella-zoster virus.

Recommended schedule

DoseAge
Dose 112-15 months
Dose 24-6 years

Side effects

Common (mild, resolve in 1-2 days)

  • Soreness, redness, or swelling at injection site (20-30%)
  • Mild fever (10-15%)
  • Mild rash at injection site or generalized (3-5%, usually fewer than 10 spots)
  • Fussiness or irritability
  • Fatigue

Serious (very rare)

  • Febrile seizure — rare, slightly more common with MMRV (ProQuad) than separate MMR + varicella
  • Pneumonia — extremely rare
  • Severe allergic reaction (anaphylaxis) — approximately 1 in 1 million doses
  • Disseminated vaccine-strain infection — extremely rare, almost exclusively in immunocompromised individuals

Who should NOT get this vaccine

  • Severe allergic reaction (anaphylaxis) to a previous dose or vaccine component (gelatin, neomycin)
  • Severe immunodeficiency (HIV with severe immunosuppression, chemotherapy, high-dose immunosuppressive therapy)
  • Pregnancy (wait 4 weeks after vaccination before becoming pregnant)
  • Recent blood product or immunoglobulin (wait 3-11 months depending on product)
  • Active untreated tuberculosis

Effectiveness

One dose is 85% effective at preventing any chickenpox and 97-100% effective at preventing severe chickenpox. Two doses are 88-98% effective at preventing any chickenpox. Breakthrough cases after vaccination are typically very mild with fewer than 50 lesions and no fever.

Available brands

Varivax

Merck

ProQuad

Merck (combination MMRV — MMR plus varicella)

Myths vs. facts

Myth: “Chickenpox is a harmless childhood illness”

Fact: Before the vaccine, chickenpox caused approximately 10,600 hospitalizations, 100-150 deaths per year in the US, and serious complications including bacterial skin infections, pneumonia, encephalitis, and toxic shock syndrome. Even healthy children can develop severe complications.

Myth: “Natural chickenpox provides better immunity”

Fact: Natural chickenpox also establishes the virus permanently in nerve cells, creating a risk of shingles later in life. The vaccine provides strong immunity with a much lower risk of shingles. Children vaccinated against chickenpox are 78% less likely to develop shingles than those who had natural infection.

Myth: “It's better to have a chickenpox party”

Fact: Intentionally exposing children to chickenpox is dangerous. You cannot predict which children will develop serious complications. Before the vaccine, about 1 in 500 children required hospitalization, and some died. The vaccine provides safe, controlled immunity without these risks.

Frequently asked questions

Can my child get chickenpox from the vaccine?
About 3-5% of children develop a very mild rash with fewer than 10 spots after vaccination. This is much milder than natural chickenpox (which causes 250-500 spots) and is rarely contagious. True breakthrough chickenpox after exposure to wild virus is also typically very mild.
Should I choose MMRV or separate MMR + varicella?
For the first dose at 12-15 months, the CDC notes a slightly higher risk of febrile seizures with MMRV (ProQuad) compared to separate injections (about 1 extra febrile seizure per 2,300 doses). Parents can discuss the preference with their pediatrician. For the second dose at 4-6 years, MMRV is preferred as the seizure risk difference disappears.
If my child was exposed to chickenpox, is it too late to vaccinate?
No. Post-exposure vaccination within 3-5 days of exposure can prevent or significantly reduce the severity of chickenpox. If your unvaccinated child is exposed, contact your pediatrician immediately about emergency vaccination.
Will my child still get shingles later in life?
The risk of shingles is significantly lower in vaccinated children compared to those who had natural chickenpox. Studies show a 78% lower risk. The weakened vaccine virus can establish latency in nerve cells but reactivates much less frequently than wild-type virus.

Sources

CDCAAPWHO

All content follows our editorial policy and is reviewed against published clinical guidelines.

2,705 evidence-based guides6 authoritative medical sources

Bottom line

The Varicella (Chickenpox) Vaccine (VAR) is safe, well-studied, and recommended by the CDC, AAP, and WHO. Talk to your pediatrician if you have questions about timing or your child's specific health needs.

Choosing to vaccinate your child is one of the most important things you can do to protect their health. If you have concerns, your pediatrician is always happy to talk through them with you.