What Happens If Varicella Vaccine Is Administered Intramuscularly?

Varicella, or chicken pox, typically has mild symptoms but may cause serious complications for infants and adults. Since the first varicella vaccine was licensed in 1995 in the United States, routine vaccination has significantly reduced the number of varicella cases and related hospitalizations and deaths.

A Live-Attenuated Virus Vaccine

• Varicella vaccine is made from an attenuated, or weakened, form of the varicella zoster virus, the organism that causes varicella.

ACIP Recommendations

• The Advisory Committee on Immunization Practices (ACIP) recommends that health care providers always administer vaccines according to the route, site, dose and number of doses recommended by the vaccine manufacturer.

Route of Injection

• Live-attenuated vaccines, which include vaccines against varicella, measles, mumps and rubella, should be injected subcutaneously, or under the skin.

Intramuscular Injection

• When varicella vaccine is mistakenly administered intramuscularly, or into the muscle, instead of subcutaneously, the ACIP recommends that this dose be considered valid. Although the vaccine was not given according to recommendations, the patient does not need a repeat dose to be protected.

Reporting Mistakes

• The person who administered the vaccine should report the error to the Institute for Safe Medication Practices (ISMP), a federally certified Patient Safety Organization that monitors medication errors and makes recommendations to prevent future errors.