Is there a contraindication to placing a Tuberculin Skin Test (TST) in a patient who has had Varicella and Measles, Mumps, and Rubella (MMR) vaccines in the last six weeks?

Tuberculin Skin Test After Recent MMR and Varicella Vaccination

There is no contraindication to placing a tuberculin skin test (TST) in a patient who received MMR and varicella vaccines within the last six weeks, but the timing matters critically for test accuracy. 1, 2

Recommended Timing Strategy

You have two acceptable options for TST placement after live virus vaccination:

• Option 1: Administer the TST on the exact same day as the live vaccines (MMR and varicella), using different anatomic sites 2
• Option 2: Wait the full 4-6 weeks after live vaccine administration before placing the TST 1, 2

The critical window to avoid is days 2-28 after vaccination, as this is when measles-containing vaccines can temporarily suppress tuberculin reactivity, potentially causing false-negative results in patients with true M. tuberculosis infection 1, 2.

Why This Timing Matters

Live-attenuated measles vaccine can suppress the immune response to tuberculin testing, but this suppression does not occur within the first 48 hours after vaccination 2. The problematic period begins around day 2 and extends through weeks 4-6 post-vaccination 2. During this window, administering a TST may yield a false-negative result due to temporary immunosuppression caused by the live virus vaccine 1.

Specific Vaccines That Affect TST Results

Both vaccines your patient received can interfere with TST interpretation:

• MMR vaccine (measles, mumps, rubella) 1, 2
• Varicella vaccine 1, 2

Other live vaccines with similar effects include oral polio, yellow fever, BCG, and oral typhoid 2.

Clinical Decision Algorithm

If the patient received vaccines within the last 6 weeks:

• Days 0-1 post-vaccination: Safe to place TST 2
• Days 2-28 post-vaccination: Avoid TST placement - highest risk for false-negative results 2
• After 4-6 weeks post-vaccination: Safe to place TST 1, 2

If urgent TST is needed during the critical window (days 2-28): You may proceed with testing, but interpret results with caution, understanding that tuberculin reactivity might be reduced and a negative result may not reliably exclude M. tuberculosis infection 1.

Important Clarifications

This is a precaution, not a contraindication. The only true contraindications to TST are severe adverse reactions to prior testing, including ulceration, necrosis, vesiculation, bullae at the test site, or anaphylactic shock 1.

Untreated active tuberculosis is a precaution for MMR vaccination (not for TST), and antituberculous therapy should be initiated before administering MMR to persons with untreated active tuberculosis 1. However, tuberculin testing is not a prerequisite for routine MMR vaccination 1.

Recent Contradictory Evidence

A 2025 study of 158,484 children challenged the traditional recommendation by finding that TST and IGRA positivity rates were actually higher (not lower) when testing occurred 1-28 days after live-virus vaccination compared to testing before or after this interval 3. The adjusted odds of positive TST results were 2.40-3.81 times higher during the "critical interval" 3. This suggests the concern about false-negatives may be overstated, though current ACIP guidelines still recommend the 4-6 week delay 1, 2.

Common Pitfalls to Avoid

• Don't confuse this with inactivated vaccines: Inactivated vaccines can be administered at any time before, with, or after tuberculin testing without affecting results 2
• Document both procedures carefully: Proper documentation prevents confusion during the 48-72 hour TST reading period 2
• Don't delay necessary vaccination: If tuberculosis screening wasn't done before vaccination, either test immediately (same day) or wait the full 4-6 weeks rather than testing in the problematic window 2