What are the protective vaccine titers for common diseases, such as Measles, Mumps, and Rubella (MMR) and Hepatitis B?

Protective Vaccine Titers for Common Diseases

For MMR and Hepatitis B vaccines, protective immunity is determined by specific antibody levels, with two doses of MMR providing 96% effectiveness against measles and 86% against mumps, while Hepatitis B protection is indicated by anti-HBs levels ≥10 mIU/mL. 1

Measles, Mumps, and Rubella (MMR)

Measles

• Protective immunity: Presence of measurable IgG antibody
• Effectiveness:
  • 95% after one dose
  • 96% after two doses 2
• Testing approach: Serologic testing for IgG antibody is widely available 1
• Protection duration: Long-term, likely lifelong protection after two doses 1

Mumps

• Protective immunity: Presence of measurable IgG antibody
• Effectiveness:
  • 72% after one dose (Jeryl Lynn strain)
  • 86% after two doses (Jeryl Lynn strain) 2
• Field studies note: Lower effectiveness estimates (75-95%) have been documented in outbreak situations 1

Rubella

• Protective immunity: Presence of measurable IgG antibody
• Effectiveness: 89% after vaccination 2
• Protection duration: Long-term, probably lifelong protection 1

Important MMR considerations:

• Almost all persons who don't respond to the first dose of measles component will respond to the second dose 1
• The second dose is not considered a booster but ensures immunity in those who failed to respond to the first dose 1
• Although antibody titers may be lower than those from natural infection, vaccine-induced immunity effectively protects against clinical illness 1

Hepatitis B

• Protective immunity: Anti-HBs (antibody to hepatitis B surface antigen) level ≥10 mIU/mL
• Vaccination schedule: 3-dose series at recommended intervals
• Special considerations:
  • Children who received their last HepB dose at age <24 weeks should receive an additional dose at age >24 weeks 1
  • A child whose records indicate receipt of 3 or more doses with at least one dose administered at age >24 weeks can be considered protected 1

Testing for Vaccine Immunity

When to test for immunity:

1. Internationally adopted children: May need antibody testing if vaccination records are uncertain 1
2. Healthcare workers: To verify immunity status
3. Immunocompromised patients: May need testing to verify protection 1
4. Post-exposure situations: To determine need for prophylaxis

Testing approach by vaccine:

• MMR: Serologic testing for IgG antibody is widely available for measles and rubella 1
• Hepatitis B: Test for anti-HBs to confirm protection
• Poliovirus: Neutralizing antibody testing available for types 1,2, and 3 1

Common Pitfalls in Vaccine Titer Interpretation

1. Timing of testing: Testing too soon after vaccination may not reflect true immunity
2. Waning antibody levels: Some vaccines show declining antibody levels over time but may still provide clinical protection
3. Immunocompromised patients: May have inadequate response despite vaccination 1
4. Interpretation without clinical context: Low antibody levels don't always indicate susceptibility

Special Populations

Immunocompromised patients:

• May require more frequent monitoring of antibody levels
• May need higher or additional doses to achieve protection 1
• For multiple myeloma patients, antibody testing ≥1 month after vaccination is recommended 1

International adoptees:

• For children with uncertain vaccination records, serologic testing can help determine protection
• A protective antibody concentration indicates valid previous vaccination 1
• For children without documentation, revaccination is often the simplest approach 1

Remember that while antibody titers are useful indicators of protection, the ultimate goal is to prevent clinical disease. The two-dose MMR schedule and three-dose Hepatitis B schedule are designed to maximize protection in the general population.