2.4.2 Concomitant or recent vaccines or viral illnesses

TB infection testing may result in false negatives in individuals with certain viral illnesses (e.g. measles) or live virus vaccination (e.g. measles or mumps) within the preceding 30 days (23). This has been described with TST, but a similar effect with all TB infection tests is biologically plausible. Hence, it may be appropriate to delay the TB infection test for 30 days after infection or vaccination. Alternatively, a negative TB infection test may be repeated after 30 days.

A common question in recent years has been the impact of coronavirus disease (COVID-19) infection or vaccination on TB infection testing. To date, no studies of TST or IGRA results after COVID-19 vaccination have been published. Given what is known about the immunological response to COVID-19 mRNA vaccination, such vaccination would not be expected to change TST or IGRA results (24). However, given that test results could (at least theoretically) be modified by immunization, it may be prudent to test before the vaccine or postpone testing for a few weeks after the vaccine where possible (25).

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