After unexpectedly finding a case of long-term persistence of Measles virus (MV) vaccine strain (MVVS) in the nasopharynx of a child, the Public Health Laboratory in Brisbane investigated swabs from a large no of airway samples collected 2013-2017. They here report 11 RT-PCR positive findings of MV in respiratory samples collected 101-784 days after vaccination, none with symptoms of measles or indication of human-human transfer. Sequencing revealed MVVS in 10/10 samples. In 4/4 patients, simultaneously taken urine samples were negative for MV RNA. The findings, which need to be repeated by other labs to exclude contamination, suggest local and long-term persistence of MVVS in the nasopharynx of vaccinated children. McMahon and her coworkers will proceed to investigate whether the MVVS detected resulted from replication of live virus, or from a non-infectious RNA transcription. Most likely, these results have implications for better understanding of the efficacy of live virus vaccines such as measles.
Measles Vaccine Virus RNA in Children More Than 100 Days after Vaccination. McMahon J, Mackay IM, Lambert SB. Viruses. 2019 Jul 10;11(7). pii: E636. doi: 10.3390/v11070636. PMID: 31295941