Main Content

Health Requirements FAQs

1. What is a 2-step TB skin test (TST)?

Tuberculin Skin Test (TST) is a screening method developed to evaluate an individual’s status for active Tuberculosis (TB) or Latent TB infection.

A 2-Step TST is recommended for initial skin testing of adults who will be periodically retested, such as healthcare workers.

A 2 step is defined as two TST’s done within 1 month of each other.

2. What is the procedure for 2-step TB skin test?

Both step 1 and step 2 of the 2 step TB skin test must be completed within 28 days. See the description below.


Visit 1, Day 1

Administer first TST following proper protocol
A dose of PPD antigen is applied under the skin

Visit 2, Day 3 (or 48-72 hours after placement of PPD)

The TST test is read

  • Negative - a second TST is needed. Retest in 1 to 3 weeks after first TST result is read.
  • Positive - consider TB infected, no second TST needed; the following is needed:- A chest X-ray and medical evaluation by a physician is necessary.

If the individual is asymptomatic and the chest X-ray indicates no active disease, the individual will be referred to the health department.


Visit 3, Day 7-21 (TST may be repeated 7-21 days after first TB skin test is read)

A second TST is performed: another dose of PPD antigen is applied under the skin

Visit 4, 48-72 hours after the second TST placement

The second test is read.

  • Negative - consider person not infected.
  • Positive - consider TB infection in the distant past.

The individual is referred for a chest X-ray and evaluation by a physician. An asymptomatic individual whose chest X-ray indicates no active disease will be referred to the health department.

3. From where can I get the TB skin test or vaccinations?

The test may be done at any MEA, Trust Care, primary care clinic or local health department. Vaccinations are also available at local pharmacies i.e. Walgreens, Kroger, CVS.

4. Why is the 2-step TB skin test needed?

Booster Phenomenon: the reason for the for 2-step TB skin test

Some people infected with M. tuberculosis may have a negative reaction to the TST if many years have passed since they became infected. They may have a positive reaction to a subsequent TST because the initial test stimulates their ability to react to the test.This is commonly referred to as the “booster phenomenon” and may incorrectly be interpreted as a skin test conversion (going from negative to positive).

For this reason, the “two-step method” is recommended at the time of initial testing for individuals who may be tested periodically (e.g., health care workers).

5. What is BCG vaccine?

BCG, or bacille Calmette-Guerin, is a vaccine for tuberculosis (TB) disease. Many foreign-born persons have been BCG-vaccinated. BCG is used in many countries with a high prevalence of TB to prevent childhood tuberculous meningitis and military disease.

6. What is the recommended TB screening test for prior BCG recipients?

A blood test is recommended (QuantiFERON TB Gold or T-spot blood test).

BCG vaccination may cause a false-positive reaction to the TST. Consequently, individuals who were vaccinated against TB with BCG vaccine should not do a TB skin test.

When TB blood test (IGRA) is used for serial testing, there is no need for a second test because boosting does not occur.

7. What is a titer?

Serum titers are blood tests that measure whether or not you are immune to a given disease(s). More specifically a quantitative serum titer is a titer with a numerical value indicating your actual degree of immunity to a disease(s).

IgG vs. IgM titers – you need IgG titers; DO NOT get labs for IgM.

8. What is considered acceptable evidence of immunity to measles and mumps & *rubella?

Acceptable presumptive evidence of immunity against measles includes at least one of the following:

  • Written documentation of adequate vaccination: 2 doses of measles-containing vaccine (MMR) for school-age children, adolescents, and adults at high risk, including college students, healthcare personnel, and international travelers
  • Laboratory evidence of immunity
  • Laboratory confirmation of measles and mumps (verbal history of measles does not count)
  • *Rubella: 1 dose of MMR vaccination

9. Can a tuberculin skin test (TST) be given on the same day as a dose of MMR and Varicella vaccine?

A TST can be applied before or on the same day that MMR and Varicella vaccine are given. However, if MMR or Varicella vaccine is given on the previous day or earlier,TST should be delayed for at least 28 days.

Live measles vaccine given prior to the application of a TST can reduce the reactivity of the skin test because of mild suppression of the immune system.

10. What is considered acceptable evidence of immunity to varicella?

The Advisory Committee on Immunization Practices (ACIP) considers evidence of immunity to varicella to be:

  • Written documentation of 2 doses of varicella vaccine given no earlier than age 12 months with at least 4 weeks in-between doses.
  • A healthcare provider's diagnosis of varicella or verification of history of varicella disease.
  • History of herpes zoster, based on healthcare provider diagnosis.
  • Laboratory evidence of immunity or laboratory confirmation of disease.

11. What is considered acceptable evidence of immunity to Hepatitis B?

3 doses of the Engerix-B or Recombivax HB vaccine or 2 doses of Heplisav-B vaccine and serological proof of immunity to hepatitis B virus (quantitative anti-HBs).

This is a requirement for all non-employees who perform tasks that may involve exposure to blood or bloody body fluids.