Dear Colleague Letters

TB Tests and mRNA COVID-19 Vaccines

January 7, 2021

Dear Colleagues:

COVID-19 vaccination is an important tool to help stop the pandemic, and CDC recommends healthcare personnel be among those offered the first doses of COVID-19 vaccines.  As the U.S. COVID-19 vaccination program continues, some may have questions about the interaction between new COVID-19 mRNA vaccines and tests used for tuberculosis (TB) infection.

There are no data to inform the impact of the COVID-19 mRNA vaccines on either the tuberculin skin test (TST) (administered by intradermal placement of 0.1 cc of purified protein derivative) or the interferon gamma release assay (IGRA). There is no immunologic reason to believe that a TST or blood draw for IGRA will impact the effectiveness of COVID-19 mRNA vaccines. 

According to the Vaccine Recommendations and Guidelines of the Advisory Committee on Immunization Practices (ACIP), inactive vaccines do not interfere with TB test results. Vaccination with live viruses (such as the MMR vaccine) can cause mild immune system suppression, and may reduce the reactivity of the TST, possibly causing a false-negative reaction.

Although the COVID-19 mRNA vaccine is not a live virus vaccine, not enough is yet known of the potential impact of mRNA vaccines on immune responses to say conclusively whether the COVID-19 mRNA vaccine could have a potential effect on TST or IGRA test results during the first 4 weeks after COVID-19 vaccination.

For healthcare personnel or patients who require baseline TB testing (at onboarding or entry into facilities) at the same time they are to receive a COVID-19 mRNA vaccine, CDC recommends:

  • Perform TB symptom screening on all healthcare personnel or patients.
  • If using IGRA, draw blood prior to COVID-19 mRNA vaccination.
  • If using TST, place prior to COVID-19 mRNA vaccination.
  • If COVID-19 mRNA vaccination has already occurred, defer TST or IGRA until 4 weeks after completion of 2-dose COVID-19 mRNA vaccination.

For healthcare personnel who require testing for other reasons, CDC recommends:

  • Perform TB symptom screening on all healthcare personnel.
  • Test for TB infection before or during the same visit as COVID-19 mRNA vaccination. If this is not possible, prioritization of testing for TB infection needs to be weighed with the importance of receiving COVID-19 mRNA vaccination based on potential COVID-19 exposures and TB risk factors.
    • Healthcare personnel with high-risk conditions for TB progression should be fully evaluated as soon as possible.
    • Healthcare personnel without high-risk conditions for TB progression should proceed with contact tracing (symptom screening, chest radiograph or other imaging, specimen for microbiologic evaluation) but delay being tested for TB infection (with either TST or IGRA) if prioritized for receiving COVID-19 mRNA vaccination.

All potential recipients of COVID-19 mRNA vaccination should weigh the risks and benefits of delaying TST/IGRA with their healthcare providers. 

For more information, please visit Interim Clinical Considerations for Use of mRNA COVID-19 Vaccines Currently Authorized in the United States and Understanding mRNA COVID-19 Vaccines.

Thank you for your continued hard work in the COVID-19 response, and in all that you do to continue to prevent and control TB.



Terry Chorba
Terence Chorba, MD, DSc
Chief, Field Services Branch, Division of Tuberculosis Elimination
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Centers for Disease Control and Prevention
1600 Clifton Road NE (US 12-4), Atlanta, GA 30329