Varicella Prophylaxis Recommendations

Vaccination Recommendations

• The Centers for Disease Control and Prevention recommends varicella prophylaxis to include vaccination of all susceptible individuals without evidence of immunity, with post-exposure vaccination within 3-5 days of exposure and VariZIG administration for high-risk individuals with contraindications to vaccination 1, 2
• For children 12 months to 12 years, a routine two-dose vaccination schedule with the first dose at 12-15 months and second dose at 4-6 years is recommended 3, 4
• For persons 13 years and older, two doses of single-antigen varicella vaccine administered 4-8 weeks apart are recommended for those without evidence of immunity 1, 5

Priority Groups for Vaccination

• Susceptible healthcare personnel should receive special consideration for vaccination 1, 6
• Household contacts of immunocompromised persons should receive special consideration for vaccination 1

Post-Exposure Prophylaxis

• Varicella vaccine is effective when administered within 3 days of exposure, and possibly up to 5 days post-exposure, with a vaccine effectiveness of approximately 70-90% in preventing varicella 2, 6
• VariZIG should be administered to susceptible persons at high risk for severe disease and complications who have contraindications for vaccination, with maximum benefit when administered as soon as possible after exposure, but may be effective if given within 96 hours of exposure 2

Evidence of Immunity to Varicella

• Documentation of age-appropriate vaccination is considered evidence of immunity to varicella 1
• Laboratory evidence of immunity or laboratory confirmation of disease is considered evidence of immunity to varicella 1

Special Considerations

• Prenatal assessment of women for evidence of varicella immunity is recommended, and vaccination should be deferred during pregnancy 1, 5
• Vaccination may be considered for HIV-infected children with age-specific CD4+ T-lymphocyte percentages of 15-24% 3, 6

Implementation Strategies

• School and college entry requirements should be established to ensure students at all grade levels are protected against varicella 1, 3
• Healthcare institutions should assess immunity status of all personnel and vaccinate those without evidence of immunity 1

Management of Individuals with Low or Negative Varicella Titer

Evidence of Immunity Assessment

• The Centers for Disease Control and Prevention recommends that evidence of immunity to varicella includes documentation of age-appropriate vaccination, laboratory evidence of immunity, laboratory confirmation of disease, or birth in the United States before 1980 for non-healthcare workers who are not immunocompromised or pregnant 7
• Commercial ELISA tests are commonly used to detect varicella antibodies but may be less sensitive than other tests like fluorescent antibody to membrane antigen (FAMA) or latex agglutination (LA) tests 8

Vaccination Recommendations Based on Immunity Status

• The American Academy of Pediatrics and the Centers for Disease Control and Prevention recommend administering 2 doses of varicella vaccine with an interval of 4 weeks between doses for VZV-seronegative individuals 9, 10
• For healthcare personnel with negative or uncertain history of varicella, serologic screening before vaccination is cost-effective 8
• The Centers for Disease Control and Prevention recommends that healthcare personnel with low or negative titers should receive vaccination to prevent potential nosocomial transmission to high-risk patients 7

Special Considerations

• The American Gastroenterological Association recommends that live varicella vaccination is contraindicated in patients receiving immunosuppressive therapy or with significant protein-calorie malnutrition 11, 12
• For patients on immunomodulators who are varicella antibody negative, consideration of vaccination during a treatment window is recommended if possible 11, 12

Post-Exposure Management

• The Centers for Disease Control and Prevention recommends that unvaccinated individuals exposed to varicella should receive post-exposure vaccination as soon as possible 7

Important Caveats

• The Centers for Disease Control and Prevention notes that documented receipt of 2 doses of varicella vaccine supersedes results of subsequent serologic testing 7, 13
• The Centers for Disease Control and Prevention recommends that healthcare institutions should establish protocols for screening, vaccinating, and managing personnel after workplace exposures 7

Varicella Vaccination Guidelines for Patients with Low Titers

Understanding Varicella Immunity

• A varicella titer of 0.06 is significantly below the protective threshold of ≥0.3 gpELISA units that defines seroconversion and immunity, according to the Centers for Disease Control and Prevention 14
• Patients with titers <5 gpELISA units are 3.5 times more likely to develop breakthrough varicella compared to those with titers >5 units, as reported by the Centers for Disease Control and Prevention 14

Vaccination Recommendations

• For patients aged ≥13 years, the American Academy of Pediatrics recommends administering 2 doses of single-antigen varicella vaccine separated by 4-8 weeks 15, 16, 17
• For children aged 1-12 years, the American Academy of Pediatrics recommends administering 2 doses separated by ≥3 months, with the second dose providing significantly improved immunologic response with 99.6% achieving protective titers (>5 gpELISA units) compared to 85.7% after one dose 14, 15, 17

Critical Considerations Before Vaccination

• If immunocompetent, proceed with standard 2-dose vaccination schedule, as recommended by the Infectious Diseases Society of America 15, 16
• If on or planning immunosuppressive therapy, vaccinate ≥4 weeks before starting therapy when possible, according to the Infectious Diseases Society of America 15, 16, 17
• If highly immunocompromised, varicella vaccine is contraindicated due to risk of severe vaccine-strain disease, as stated by the Infectious Diseases Society of America and the American Gastroenterological Association 15, 16, 18

Post-Vaccination Monitoring

• Seroconversion occurs in approximately 97% of susceptible children and 79% of adolescents after one dose, with higher rates after two doses, as reported by the Centers for Disease Control and Prevention 14

Special Population Considerations

• For women of childbearing age, the Centers for Disease Control and Prevention recommends counseling to avoid conception for 1 month after each vaccine dose 19
• For HIV-infected patients, the Centers for Disease Control and Prevention recommends vaccination if CD4+ T-lymphocyte count >200 cells/µL (adults) or CD4+ percentage >15% (children), using 2 doses separated by 3 months 15, 19