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Timing of TST or IGRA in relation to JYNNEOS vaccine

September 23, 2022

Dear Colleagues,

At the Division of Tuberculosis Elimination (DTBE), several inquiries have been received from clinicians and public health authorities about the timing of the tuberculin skin test (TST) or an interferon gamma release assay (IGRA) in relation to the JYNNEOS vaccine.

JYNNEOS is approved by the Food and Drug Administration (FDA) for prevention of smallpox and mpox disease in adults 18 years or older at high risk for smallpox or mpox infection (CDC JYNNEOS overview, FDA JYNNEOS EAU). The effects of JYNNEOS on TST and IGRA performance have not been studied, and, in response to inquiries, DTBE is using the following text that was reviewed and approved by the CDC mpox response staff:

Timing of tuberculin skin test (TST) or interferon gamma release assay (IGRA) with JYNNEOS vaccine

“After live virus vaccines, tuberculosis (TB) testing with the tuberculin skin test (TST) or TB-specific interferon gamma release assays (IGRA) should be delayed for at least 4 weeks if the TB testing cannot be done at the time of vaccination.

While JYNNEOS is a live virus vaccine, it is non-replicating and its effect on the response to TST and IGRA may not be the same as for live, replicating virus vaccines such as measles-mumps-rubella (MMR). In the absence of specific data, the effects of JYNNEOS vaccination on TST or IGRA results are unknown.

Therefore, if a delay in TB testing with TST or IGRA for 4 weeks would cause substantial burden (for example, preventing a person from working because of pre-employment screening policies), then TST and IGRA testing should not be delayed. If delays in TB testing will not cause substantial burden, a delay of at least 4 weeks after JYNNEOS vaccination is preferred. This recommendation is subject to change should JYNNEOS-specific data for TB testing become available.

TB testing with TST or IGRA can be done at the same time as JYNNEOS vaccination, as with other vaccines, and any sequence of vaccination and TB testing may be used at that time.

For patients who have symptoms or signs of active TB disease, all tests and examinations for TB diagnosis should be pursued without delay, regardless of JYNNEOS vaccination.”

Administration of tuberculin skin test (TST) or interferon gamma release assay (IGRA) with JYNNEOS vaccine

“The JYNNEOS vaccine is routinely administered on the volar surface of the forearm (that is, on the same side as the palm), as is the TST. JYNNEOS and TST can cause similar local reactions, such as redness and induration at the site of injection.

If the JYNNEOS vaccine and the TST are administered at the same time, the vaccine and the test should be administered on opposite arms, one on the left and one on the right, and the location of each injection site should be recorded, to document the correct arm for reading the result from the TST.

If the JYNNEOS vaccine and the TST are administered on the same arm, the sites of injection should be separated by 8–10 centimeters (that is, 3–4 inches) along the length of the arm, for reducing any overlap of the reactions, and the location of each injection site should be recorded.

If an IGRA is done during the same visit as JYNNEOS vaccination, either arm can be used for blood collection.”

Please contact the DTBE project officer for your cooperative agreement or Dr. John Jereb,, with your questions.


Thank you.

Terence Chorba, MD, DSc, LLM, MPH, MPA, FACP, FIDSA
Chief, Field Services Branch, Division of Tuberculosis Elimination
National Center for HIV, Viral Hepatitis, STD, and TB Prevention
Centers for Disease Control and Prevention