Pre-Employment Immunizations and Screening for School Workers
All school employees must complete tuberculosis screening with either a tuberculin skin test (TST/PPD) or interferon-gamma release assay (IGRA) before starting work, with IGRA preferred in individuals with prior BCG vaccination. 1
Tuberculosis Screening Requirements
Baseline Testing Before Employment
- Healthcare personnel and school workers require baseline TB screening prior to starting work, consisting of an individual risk assessment, symptom evaluation (cough, fever, night sweats, weight loss, hemoptysis), and testing with either IGRA or TST. 1
- IGRA is preferred over TST in the following situations: 2, 1
- Individuals with prior BCG vaccination (TST produces false-positives in this population)
- Situations where patient return for TST reading is unlikely
- Patients already on immunosuppressive therapy
Test Selection and Performance
- Either IGRA (QuantiFERON-TB Gold) or TST can be used for baseline screening, and both tests should prompt the same evaluation and management if positive. 2
- IGRA offers significant operational advantages for pre-employment screening: it requires only a single visit (versus two for TST), increases completion rates from 77% to 97%, reduces clearance-to-work time from 13 days to 6 days, and cuts screening costs by 40%. 3
- In BCG-vaccinated populations, IGRA shows 92.5% agreement with TST but eliminates false-positive TST results that are the most significant issue affecting test concordance. 4
TST Administration and Reading (If Used)
- TST must be read between 48-72 hours after injection when induration reaches maximum size; tests read after 72 hours underestimate true induration and should be avoided. 5
- Measure only the transverse diameter of induration (perpendicular to the forearm's long axis) in millimeters, not erythema; document "0 mm" rather than "negative" when no induration is present. 5
- An induration diameter ≥5 mm is considered positive for any contact of an infectious TB case; interpretation thresholds vary based on individual risk factors identified in the risk assessment. 2
Follow-Up After Positive Screening
- All persons with a positive IGRA or TST require chest radiography to distinguish latent TB infection (LTBI) from active TB disease. 1
- For asymptomatic persons at low risk with a positive initial test, perform a second confirmatory test (either IGRA or TST); consider infected only if both tests are positive. 1
- All persons with untreated LTBI should receive treatment unless medically contraindicated, with preferred regimens including isoniazid plus rifapentine once weekly for 3 months or rifampin alone daily for 4 months. 1
Special Considerations
- Do not perform testing in persons with documented prior LTBI or TB disease; these individuals require only clinical evaluation if TB disease is suspected. 2, 1
- Both IGRA and TST may be less sensitive in severely immunosuppressed individuals, and a negative result alone should not exclude infection in high-risk groups. 2
- Recent live-virus vaccination does not cause false-negative TB test results and should not delay testing; the traditional 4-week waiting period after vaccination is not supported by evidence. 6
Additional Immunizations for School Workers
While TB screening is the primary pre-employment requirement explicitly addressed in occupational health guidelines, school workers typically require standard healthcare worker immunizations based on CDC recommendations, though specific requirements vary by state and institution. Common requirements include measles-mumps-rubella (MMR), varicella, tetanus-diphtheria-pertussis (Tdap), hepatitis B, and annual influenza vaccination, with documentation of immunity through serology or vaccination records.