Implications of Measles Inclusion by Commercial Syndromic Polymerase Chain Reaction Panels - United States, May 2022-April 2023.

Syndromic polymerase chain reaction (PCR) panels are used to test for pathogens that can cause rash illnesses, including measles. Rash illnesses have infectious and noninfectious causes, and approximately 5% of persons experience a rash 7-10 days after receipt of a measles, mumps, and rubella (MMR) vaccine. MMR vaccine includes live attenuated measles virus, which is detectable by PCR tests. No evidence exists of person-to-person transmission of measles vaccine virus, and illness does not typically result among immunocompetent persons. During September 2022-January 2023, the Tennessee Department of Health received two reports of measles detected by syndromic PCR panels. Both reports involved children (aged 1 and 6 years) without known risk factors for measles, who were evaluated for rash that occurred 11-13 days after routine MMR vaccination. After public health responses in Tennessee determined that both PCR panels had detected measles vaccine virus, six state health departments collaborated to assess the frequency and characteristics of persons receiving a positive measles PCR panel test result in the United States. Information was retrospectively collected from a commercial laboratory testing for measles in syndromic multiplex PCR panels. During May 2022-April 2023, among 1,548 syndromic PCR panels, 17 (1.1%) returned positive test results for measles virus. Among 14 persons who received a positive test result and for whom vaccination and case investigation information were available, all had received MMR vaccine a median of 12 days before specimen collection, and none had known risk factors for acquiring measles. All positive PCR results were attributed to detection of measles vaccine virus. Increased awareness among health care providers about potential measles detection by PCR after vaccination is needed. Any detection of measles virus by syndromic PCR testing should be immediately reported to public health agencies, which can use measles vaccination history and assessment of risk factors to determine the appropriate public health response. If a person recently received MMR vaccine and has no risk factors for acquiring measles, additional public health response is likely unnecessary.

Mumps Outbreak at a University and Recommendation for a Third Dose of Measles-Mumps-Rubella Vaccine - Illinois, 2015-2016.

Mumps is an acute viral disease characterized by fever and swelling of the parotid or other salivary glands. On May 1, 2015, the Illinois Department of Public Health (IDPH) confirmed a mumps outbreak at the University of Illinois at Urbana-Champaign. IDPH and the Champaign-Urbana Public Health District (C-UPHD) conducted an investigation and identified 317 cases of mumps during April 2015-May 2016. Because of sustained transmission in a population with high 2-dose coverage with measles-mumps-rubella (MMR) vaccine, a third MMR dose was recommended by IDPH, C-UPHD, and the university's McKinley Health Center. No formal recommendation for or against the use of a third MMR dose has been issued by the Advisory Committee on Immunization Practices (ACIP) (1). However, CDC has provided guidelines for use of a third dose as a control measure during mumps outbreaks in settings in which persons are in close contact with one another, where transmission is sustained despite high 2-dose MMR coverage, and when traditional control measures fail to slow transmission (2).