Recommended Vaccine Antibody Titers and Protective Thresholds
Hepatitis B
For hepatitis B, a protective antibody titer is ≥10 mIU/mL, with >95% of vaccine recipients achieving this threshold when the series is completed according to schedule. 1
- The standard hepatitis B vaccination series consists of 2 or 3 doses depending on the formulation used (2-dose Heplisav-B at least 4 weeks apart, or 3-dose Engerix-B/Recombivax HB at 0,1, and 6 months). 2
- Higher antibody titers are achieved when the third dose is administered at 12 or 15 months of age in infants, and higher titers ensure longer antibody persistence. 1
- For hemodialysis patients, use a special 40 mcg/mL formulation or two 1.0 mL doses, assess anti-HBs levels annually, and administer additional doses if levels decline below 10 mIU/mL. 3
Measles, Mumps, and Rubella (MMR)
Laboratory evidence of immunity to measles, mumps, and rubella is defined by the presence of detectable antibodies via serologic testing, though specific protective titer thresholds are not routinely quantified in clinical practice. 4
Measles
- Acceptable evidence of immunity includes documentation of two doses of live measles vaccine given at least 1 month apart after the first birthday, laboratory evidence of immunity, or documentation of physician-diagnosed disease. 4
- Seroprotection rates of 88% have been documented in adult populations, with rates below the 95% threshold required for elimination in some groups. 5
- Healthcare workers born before 1957 should be offered vaccine if there is reason to believe they may be susceptible, as 29% of healthcare workers with measles in 1985-1989 were born before 1957. 4
Mumps
- One dose of live mumps vaccine or laboratory evidence of immunity constitutes acceptable evidence for persons born in 1957 or later. 4
- Seroprotection rates of approximately 91% have been documented in adult populations. 5
Rubella
- Persons are considered immune only with a record of vaccination on or after their first birthday or laboratory evidence of immunity; physician diagnosis is not adequate evidence. 4
- Seroprotection rates of 94% have been documented in adult populations. 5
- Women of childbearing age without proof of vaccination or laboratory evidence should receive rubella vaccine. 4
Varicella
Varicella immunity is demonstrated by laboratory evidence of antibodies, with seroprotection rates of approximately 96% in vaccinated populations. 5
- Acceptable evidence of immunity includes documentation of age-appropriate vaccination (two doses for children, adolescents, and adults), laboratory evidence of immunity or disease confirmation, or birth in the United States before 1980 (except for healthcare workers and pregnant women). 6
- Varicella vaccine response rates of approximately 90% have been documented after the two-dose series. 7
Tetanus and Diphtheria
Protective tetanus antibody levels are maintained through completion of a primary three-dose series followed by booster doses every 10 years, though specific quantitative thresholds are not routinely measured in clinical practice. 4, 1, 4
- The primary series consists of three doses of Td given at 0,4-8 weeks, and 6-12 months. 4
- Among persons 6-16 years who received their most recent tetanus vaccination 6-10 years previously, 28% had tetanus antibody titers lower than protective levels. 1
- Persons with unknown or uncertain vaccination histories should be considered unvaccinated and receive a full three-dose primary series. 4
Pertussis
Pertussis immunity is assessed through completion of the DTaP/Tdap vaccination series rather than antibody titers, as correlates of protection are not well-established. 1, 8
- The primary DTaP series consists of doses at 2,4,6, and 15-18 months, with a fifth dose at 4-6 years. 1
- Adults should receive a single dose of Tdap, with Td boosters every 10 years thereafter. 6, 8
- Pertussis toxin and filamentous hemagglutinin antibody responses of 74-90% have been documented depending on timing of vaccination. 7
Pneumococcal
Pneumococcal immunity is determined by completion of the age-appropriate vaccination series (PCV13 and/or PPSV23) rather than antibody titers, as specific protective thresholds vary by serotype. 6, 9
- Adults aged 19 years or older with immunocompromising conditions should receive PCV13 followed by PPSV23 at least 8 weeks later. 6
- Adults aged 65 years or older should receive pneumococcal vaccination according to current ACIP recommendations. 6, 4
- Revaccination with PPSV23 should be considered ≥5 years after the initial dose for those at highest risk of fatal pneumococcal disease or rapid antibody decline. 4
Influenza
Annual influenza vaccination is recommended for all persons aged 6 months or older, with immunity assessed by vaccine receipt rather than antibody titers. 2, 8
- Inactivated influenza vaccine (IIV) or recombinant influenza vaccine (RIV) should be administered annually. 2, 8
- Live attenuated influenza vaccine (LAIV) may be considered in otherwise healthy HIV-infected patients aged 5-17 years on antiretroviral therapy for ≥16 weeks with CD4 percentage ≥15 and HIV RNA <60,000 copies. 9
COVID-19
COVID-19 immunity is determined by completion of the primary vaccination series and recommended boosters according to current CDC/ACIP guidelines, with antibody testing not routinely recommended for assessing protection. 2
- Specific protective antibody thresholds for COVID-19 have not been established for clinical use, as correlates of protection continue to evolve with new variants and vaccine formulations. 2
Key Clinical Considerations
- For healthcare workers and students, serologic screening before vaccination is cost-effective for measles, mumps, rubella, and varicella given high baseline seroprevalence rates (57-96%), but vaccination without screening is more appropriate for hepatitis A and B. 10
- Self-reported vaccination or infection history is unreliable, with unknown histories ranging from 27-81% depending on the disease; therefore, serologic testing is essential for healthcare workers regardless of reported history. 11
- Children who receive their 2-month and 4-month vaccines late are 6-7 times more likely to miss MMR vaccination by age 2 years, highlighting the importance of timely early infant immunization. 12