Can a 14-year-old receive a third varicella (chickenpox) vaccine dose if their first two doses cannot be confirmed?

Varicella Vaccination for a 14-Year-Old with Unconfirmed Prior Doses

Yes, a 14-year-old should receive a varicella vaccine dose if their first two doses cannot be confirmed, as only documented doses are considered valid evidence of immunity. 1

Evidence of Immunity Requirements

According to the Advisory Committee on Immunization Practices (ACIP) and American Academy of Pediatrics (AAP) guidelines, acceptable evidence of immunity to varicella includes:

1. Documentation of 2 appropriately timed doses of varicella vaccine 1, 2
2. Laboratory evidence of immunity or laboratory confirmation of disease 1
3. Varicella diagnosed by a healthcare professional 1
4. History of herpes zoster diagnosed by a healthcare professional 1

Why Vaccination is Needed

• Self-reported vaccination history without documentation is not considered adequate evidence of immunity 1
• Neither a self-reported dose nor a history of immunization provided by a parent is, by itself, considered adequate documentation of immunity 1
• Only doses of vaccine for which written documentation of the date of administration is presented should be considered valid 1

Vaccination Approach for This Patient

For a 14-year-old without documented prior doses:

• Administer a single dose of monovalent varicella vaccine (not MMRV, which is only licensed for children 12 months through 12 years) 2
• The patient should receive a second dose at least 28 days after the first dose 1
• For persons ≥13 years of age, the minimum interval between doses is 4 weeks 1, 2

Efficacy and Safety Considerations

• Two-dose regimen provides significantly higher protection (95-98% efficacy) compared to a single dose (67-94% efficacy) 3, 4
• The risk for breakthrough disease is 3.3-fold lower among individuals who received 2 doses compared to those who received 1 dose 2, 5
• One dose of varicella vaccine has been shown to be insufficient to prevent outbreaks in school settings 5

Important Caveats

• Serologic testing to verify immunity is generally neither necessary nor recommended before vaccination if a person lacks other acceptable evidence of immunity 1
• Postimmunization serologic testing is not recommended as commercial assays may not be sensitive enough 1
• If the adolescent has a history of typical varicella disease verified by a healthcare professional, vaccination may not be necessary 1, 2

Special Considerations

• If the patient is immunocompromised, pregnant, or has severe allergies to vaccine components, varicella vaccination would be contraindicated 2
• For high-risk individuals (e.g., those with household contacts who are immunocompromised), ensuring complete vaccination is particularly important 2

By providing two appropriately spaced doses of varicella vaccine, the 14-year-old will achieve optimal protection against varicella infection, which can be more severe in adolescents and adults than in younger children.