Top 5 Takeaways

  1. Increased Detection of Measles Vaccine Virus: Approximately 1% of syndromic PCR panels conducted by a commercial laboratory tested positive for measles, mainly in children recently vaccinated against measles.
  2. Public Health Response Considerations: Positive measles results after vaccination should be reported to public health agencies to assess the need for public health response, as these do not indicate disease transmission or illness in immunocompetent persons.
  3. Characteristics of Reported Cases: All cases with positive measles PCR results had received the MMR vaccine, typically within 3 weeks prior to testing, and lacked known measles risk factors.
  4. Impact on Public Health Practices: The detection of measles virus by PCR following vaccination underscores the importance of awareness among healthcare providers regarding potential measles detection after vaccination.
  5. Guidelines for Public Health Evaluation: A proposed approach for responding to incidental measles virus detection includes considering vaccination history, clinical signs, symptoms, and risk factors to guide public health responses.

Original Article Author and Citation

Corresponding Author

Christine M. Thomas,

Suggested Citation

Thomas CM, Hartley A, Schmitz A, et al. Implications of Measles Inclusion by Commercial Syndromic Polymerase Chain Reaction Panels — United States, May 2022–April 2023. MMWR Morb Mortal Wkly Rep 2024;73:260–264. DOI:


The study highlighted the implications of including measles in commercial syndromic polymerase chain reaction (PCR) panels, emphasizing that positive measles results can occur following measles, mumps, and rubella (MMR) vaccination. These findings suggest a need for increased awareness among healthcare providers about the potential for measles virus detection by PCR after vaccination and for immediate reporting to public health agencies for appropriate response.


A retrospective collection of data from a commercial laboratory and six state health departments assessed the frequency and characteristics of individuals receiving positive measles PCR panel test results in the United States from May 2022 to April 2023.


The discussion addresses the public health implications of detecting measles virus by syndromic PCR panels following MMR vaccination, emphasizing the need for proper evaluation and reporting to avoid unnecessary public health responses. It highlights the importance of distinguishing between measles infection and detection of the vaccine virus.


The inclusion of measles in syndromic PCR panels can lead to the incidental detection of measles vaccine virus in recently vaccinated individuals, necessitating a clear understanding and response strategy among healthcare providers and public health officials to avoid unwarranted actions.

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