And Another Thing!

February 09, 2021

Apparently the COVID vaccines may have an effect on the results of either a Tuberculin Skin Test (TST) or an Interferon Gamma Release Assay (IGRA) test for TB.  Typically, there is not expected to be any interference between vaccines and the results of a TB test, however, CDC  published a “Dear Colleague Letter” on January 7, 2021 that states:

“Although the COVID-19 mRNA vaccine is not a live virus vaccine, not eneough 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 the COVID-19 vaccination.” 

So where baseline TB testing is required (at hire or admission to services), the CDC has recommended that if vaccination has occurred, that the testing (either TST or IGRA) be deferred until 4 weeks after completion of the 2nd dose of COVID-19 mRNA vaccination.   This delay will presumably be sufficient to avoid a false negative TB test.

We have requested that DBHDS issue guidance to allow selective deferral of the 30 day requirement for TB testing, where the above scenario applies.  This may not suggest any change in your on-boarding or admission procedures, but be aware that a healthcare provider award of the CDC Guidance may refuse to administer the test.