How do I interpret and manage a patient with immunity to measles, rubella, and varicella, but potential vulnerability to mumps and hepatitis B, and a positive QuantiFERON-TB (Tuberculin Blood Test) Gold result?

Laboratory Interpretation and Management Plan

This patient requires MMR vaccination for mumps immunity, completion of hepatitis B vaccine series, and immediate evaluation with chest imaging and infectious disease referral for the positive QuantiFERON-TB Gold test.

Immunity Status Interpretation

Protected Diseases

• Measles: Immune with antibody titer >300.0 mIU/mL, which exceeds the positive cutoff and confirms protection 1, 2
• Rubella: Immune with antibody titer 1.32 IU/mL (positive by standard assay) 1, 3
• Varicella: Reactive result confirms immunity; no further vaccination needed 4

Non-Immune/Inadequate Protection

Mumps (IgG <9.0): This patient is not immune to mumps and requires vaccination 4. The CDC defines persons with antibody levels below the positive cutoff as susceptible 1. Healthcare workers must have documented immunity to mumps, which is "highly desirable" and increasingly required 4.

Hepatitis B (Surface Antibody <3.5 mIU/mL): This patient is not protected against hepatitis B despite negative HBsAg 4. Any healthcare worker with blood exposure risk requires vaccination 4. Antibody levels <10 mIU/mL are considered non-protective, and this patient's level of <3.5 mIU/mL indicates either non-vaccination or non-response to prior vaccination 4.

Immediate Actions Required

1. MMR Vaccination

• Administer one dose of MMR vaccine immediately to provide mumps immunity 4
• Since the patient already has measles and rubella immunity, giving MMR is safe and will not cause adverse effects from revaccination 4, 1
• No serologic testing is needed post-vaccination 4
• Healthcare workers born in 1957 or later require documented immunity or two doses of MMR; this patient needs at least one documented dose 4

2. Hepatitis B Vaccination Series

• Initiate or complete the hepatitis B vaccine series (3 doses at 0,1, and 6 months) 4
• The negative HBsAg confirms no chronic infection, making vaccination safe and indicated 4
• Post-vaccination serologic testing (anti-HBs) should be performed 1-2 months after series completion to document response 4
• If antibody remains <10 mIU/mL after the series, consider the patient a non-responder and repeat the full 3-dose series 4

3. QuantiFERON-TB Gold Positive Management

This is the most urgent finding requiring immediate action:

• Order chest X-ray immediately to rule out active tuberculosis 5
• Refer to infectious disease or pulmonary specialist for evaluation 5
• Assess for symptoms of active TB: fever, night sweats, weight loss, cough, hemoptysis 5
• Determine risk factors: HIV status, immunosuppression, recent TB exposure, foreign birth from high-prevalence country 5

If chest X-ray is normal and active TB is ruled out, the patient has latent tuberculosis infection (LTBI) and requires treatment 5:

• Isoniazid for 9 months is the standard regimen for LTBI 5
• Alternative regimens include 4 months of rifampin or 3 months of isoniazid plus rifampin 5
• Treatment is recommended regardless of age for healthcare workers and persons with positive QuantiFERON tests 5

Critical Caveats

Do not delay tuberculosis evaluation: A positive QuantiFERON-TB Gold test requires urgent assessment to exclude active disease before considering LTBI treatment 5. Active tuberculosis poses significant morbidity and mortality risk to the patient and transmission risk to others.

Hepatitis B non-response: Approximately 5-15% of immunocompetent adults fail to respond to the initial vaccine series. If post-vaccination titers remain <10 mIU/mL, these individuals require counseling about HBIG prophylaxis after any HBsAg-positive exposure 4.

MMR in immunocompromised patients: If the positive QuantiFERON indicates HIV infection or other severe immunosuppression, defer MMR vaccination until immune status is clarified, as live vaccines are contraindicated in severely immunocompromised individuals 4.

Documentation Requirements

• Record all vaccination dates in the patient's permanent medical record 4
• Document tuberculosis evaluation results and treatment plan 5
• Ensure post-hepatitis B vaccination serology is tracked and results are available 4
• For healthcare workers, this documentation must be readily accessible to occupational health 4