May, 2021
Updated Guidance on Co-Administration of COVID-19 Vaccine and
Tuberculin Skin Test (TST) or Interferon Gamma Release Assay (IGRA) Blood Test
Background
The Centers for Disease Control and Prevention (CDC) recently updated their guidance on the co-administration of the COVID-19 vaccines with other vaccines. This included updated guidance for use of immune-based tests for tuberculosis (TB) infection, such as the tuberculin skin test (TST) and interferon-gamma release assay (IGRA), with COVID-19 vaccine. A link to the full CDC guidance is here.
Guidance
Below is CDC guidance for use of immune-based tests for TB infection, such as TST and IGRA, with the COVID-19 vaccine.
COVID-19 vaccines should not be delayed because of testing for TB infection. Testing for TB infection with one of the immune-based methods, either the TST or IGRA, can be done before or during the same encounter as COVID-19 vaccination. When testing with TST or IGRA cannot be done at the same time as COVID-19 vaccination, these tests should be delayed four weeks or more after the completion of COVID-19 vaccination, but generally should not be cancelled.
Patients who have active TB disease or an illness that is being evaluated as active TB disease can receive a COVID-19 vaccine (note: the presence of a moderate or severe acute illness is a precaution to administration of all vaccines). Whereas a TST or IGRA test is part of a comprehensive evaluation for TB disease, positive TST or IGRA results are not required to diagnose active TB disease.
When considering a tuberculin skin test or interferon-gamma release assay:
- The TST is not expected to have an effect on the safety or the effectiveness of COVID-19 vaccine. IGRAs are blood tests and therefore do not affect vaccine safety or effectiveness.
- The reliability of a positive TST or IGRA result after COVID-19 vaccination is expected to be the same as without the vaccination. COVID-19 vaccination is not expected to cause false positive results from a TB test that is done at the same encounter as or after COVID-19 vaccination.
- The reliability of a negative TST or IGRA result after COVID-19 vaccination has not been studied.
- The TST is not a vaccine. The guidance for separating other vaccines from COVID-19 vaccination by at least two weeks in time does not apply to the TST because the TST is not a vaccine.
When a tuberculin skin test or interferon gamma release assay is required by policy:
- A TST or IGRA to meet administrative requirements (for example, for health care employment or for admission to long-term care) can be done prior to COVID-19 vaccination or at the same encounter. COVID-19 vaccination should not be delayed because of testing for TB infection.
- A TST or IGRA should be deferred until four weeks or more after the completion of COVID-19 vaccination. If testing requirements or policies cannot be modified for the COVID-19 pandemic to accept this delay in TST or IGRA testing, it should be understood that a false negative TST or IGRA cannot be excluded, and consideration should be given to repeating negative TST or IGRA tests at least four weeks after the completion of COVID-19 vaccination. If TST was the initial test, boosting could be a factor if the result of the repeat test is positive.
When a tuberculin skin test or interferon gamma release assay is indicated for medical care:
- The decision on whether a TST or IGRA that is being done for medical diagnosis of latent TB infection (for example, during a contact investigation after exposure to contagious TB disease) should be delayed for four weeks after completion of COVID-19 vaccination is at the discretion of the responsible medical provider and TB Program overseeing the contact investigation. Medical providers and TB Programs may not wish to delay testing for people at high risk for progression to TB disease. However, patients who have a negative result in this context should be considered for retesting four weeks or more after the completion of COVID-19 vaccination.
Patients who have symptoms or diagnostic findings consistent with active TB disease should receive further medical evaluation—for example with chest radiography and sputum bacteriology for Mycobacterium tuberculosis—regardless of TST or IGRA results.
Wisconsin Tuberculosis (TB) Program (WTBP) Contact Information
Main WTBP phone number: 608-261-6319
WTBP fax: 608-266-0049
WTBP group email: DHSWITBProgram@dhs.wisconsin.gov
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