This guidance was generated in response to the CDC's determination that it is unclear if there is any impact of an mRNA COVID-19 vaccine on a TB test result (both TST and T spot). While some live virus vaccines can cause immune suppression and produce a false negative test result, the COVID-19 vaccine is not a "live virus" vaccine. However, experts are erring on the side of caution as the impact an mRNA vaccine can have on the immune system is unclear at this time.

The CDC further indicates that 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."

The CDC has issued the following best practices 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.

• 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.

While these testing guidelines are in effect, they may potentially impact employees who require both a TB test and a COVID-19 vaccine. Employers and subjects should be aware that a TB test can be delayed if it overlaps the employees' COVID-19 vaccine schedule, as noted above per the CDC guidelines.

SOURCE: Centers for Disease Control and Prevention

Posted: January 14, 2021