If a PPD skin test was done yesterday and the live vaccine...

Question: 

If a PPD skin test was done yesterday and the live vaccine such as MMR was given today , is the result of the PPD going to be valid if he comes back after 48 to 72 hours?

Answer: 

A TB test can be done before or on the same day that a live virus vaccine like MMR is given. However, if a live vaccine is given on the previous day or earlier, the TB test should be delayed for at least 4 weeks (28 days). If a live vaccine is given before  the TB test, it can reduce the reactivity of the skin test because of mild suppression of the immune system and result in a false negative. For further questions, please contact your immunization provider.

ImmunizeBC Nurse