Q: We have had three employees who have tested positive for influenza by nasal swab within two weeks of receiving Fluarix Quadrivalent vaccine. Is there a time period after receiving influenza vaccine that a nasal swab can give a false positive result?
A: Inactivated influenza vaccines, including Fluarix, are not known to cause false positive nasal swab tests. However, false positive test results are possible with rapid tests, and these are more likely to occur when influenza prevalence in the area is low. For more information regarding interpretation of rapid influenza tests, visit the CDC website.