Chickenpox (Varicella) Vaccines

Chickenpox, or varicella, is a highly contagious disease caused by the varicella-zoster virus (VZV). It causes an itchy, blister-like rash that appears first on the chest, back, and face, and then spreads over the entire body. Other typical symptoms include fever, tiredness, loss of appetite, and headache.

Chickenpox can be serious, especially in babies, adolescents, adults, pregnant women, and people with a weakened immune system. Some people who get chickenpox get a painful rash called shingles (also known as herpes zoster) later in life.

Learn more about chickenpox.

There are safe and effective vaccines that can protect against chickenpox.

• Serious side effects after the chickenpox vaccine are rare. The few that have been reported after vaccination include:
  • Severe rash
  • Infections of the lungs or liver
  • Meningitis
  • Seizures that are often associated with fever (febrile seizures)
  • General severe infection with the virus strain from the vaccine.
  Some children who had these serious side effects after vaccination had weakened immune systems before they were vaccinated, but the condition had not been diagnosed before the child was vaccinated.
  
  
• Before FDA licensed the vaccine, studies were done to determine the safety of 2 doses of the vaccine. In children 12 months through 12 years old:
  • 1 of 5 children had side effects, such as soreness, swelling, and redness, within 3 days of getting the first dose, compared with 1 of 4 children after the second dose.
  • 7 of 100 children had fever after the first dose, compared with 4 of 100 children after the second dose.
  • 3 of 100 children had chickenpox-like rash after the first dose, compared with 1 of 100 children after the second dose.
   
• In August 2019, Merck published a 22-year review of the varicella vaccine. The review included data collected from study reports submitted from March 17, 1995, through March 16, 2017, during which over 212 million doses were distributed globally. Researchers found a decrease of reported adverse events over time (around 500 per one million doses in 1995 and around 40 per one million doses in 2016) and serious adverse events comprised 0.8 reports per one million doses. The profiles of serious and non-serious adverse events were consistent with previously published reports, and identified no new or unusual safety concerns.Source: Varicella Virus Vaccine Live: A 22-Year Review of Postmarketing Safety Data. [Open Forum Infec Dis. 2019]external icon
  
  
• An analysis of reports during 2006-2014 after second-dose chickenpox vaccination data using the Vaccine Adverse Event Reporting System (VAERS) did not identify new or unexpected safety concerns for second dose of chickenpox vaccination.Source: Safety of Second-Dose Single-Antigen Varicella Vaccine. [Pediatrics. 2017]external icon
  
  
• Although pregnant women should not get the chickenpox vaccine, some might get the vaccine by mistake. A pregnancy registry to monitor the fetal and pregnancy outcomes of women who inadvertently received chickenpox vaccine 3 months before or at any time during pregnancy found no cases of congenital chickenpox syndrome or increased risk for other birth defects.Source: Closure of varicella-zoster virus-containing vaccines pregnancy registry – United States, 2013. [MMWR. 2014]external icon
  
  
• In 2008, a CDC-FDA report analyzed VAERS data from May 1995 through December 2005 of patients who reported side effects after getting chickenpox vaccine. The vaccine manufacturer, Merck, distributed 50 million doses of chickenpox vaccine during this time. The vast majority of reports were non-serious and mild, such as soreness at the injection site and rash. Serious side effects linked to the vaccine were rare.Source: Safety of varicella vaccine after licensure in the United States: experience from reports to the Vaccine Adverse Event Reporting System, 1995-2005. [ J Infect Dis. 2008]external icon 
  
  
• Since the varicella vaccine is a live virus vaccine, the virus can become dormant and reactivate, rarely causing serious side effects. Individual case reports of varicella vaccine virus reactivation leading to vaccine-associated herpes zoster ophthalmicus and encephalitis, and meningitis have been published.Sources:
  A case of Herpes Zoster and Meningitis in a Twice-Vaccinated Healthy adolescent. [ J Pediatr Infect Dis. 2017]external icon
  Vaccine-associated Herpes Zoster Ophthalmicus and Encephalitis in Immunocompetent Child. [Pediatrics. 2010]external icon
  Herpes Zoster and Meningitis resulting from Reactivation of Varicella Vaccine Virus in an Immunocompetent Child. [Ann Emer Med. 2009]external icon
• It is rare for vaccinated people to spread varicella vaccine virus, especially if they do not have a rash. Worldwide, since 1995, only 11 healthy vaccinated people have been documented as spreading vaccine virus to 13 unvaccinated persons. All of these vaccinated people had a rash after vaccination.