Measles Vaccine Virus RNA in Children More Than 100 Days after Vaccination

Area of Science:

• Virology
• Immunology
• Public Health

Background:

• Measles vaccines, in use since the 1960s, possess strong safety and efficacy.
• Limited data exist regarding the detection of measles vaccine virus (MeVV) RNA in individuals post-vaccination.
• Current understanding suggests MeVV RNA detection is typically confined to 14 days post-vaccination, with longer detection being uncommon.

Purpose of the Study:

• To investigate the prolonged detection of measles vaccine virus (MeVV) RNA in children.
• To analyze the implications of detecting MeVV RNA beyond the established short timeframe.
• To emphasize the necessity of viral genotyping for all measles virus detections.

Main Methods:

• Utilized real-time reverse transcription-polymerase chain reaction (RT-rPCR) assays targeting M and F genes for MeV and MeVV RNA identification.
• Employed N gene RT-rPCR for confirmatory testing.
• Performed sequence confirmation using semi-nested conventional RT-PCR assays targeting N, H, and L genes.

Main Results:

• Successfully detected and confirmed MeVV RNA in the respiratory tracts of 11 children.
• Detection occurred between 100 and 800 days post-most recent measles-containing vaccine administration.
• This finding represents a significant extension of previously documented MeVV RNA detection timelines.

Conclusions:

• The prolonged presence of MeVV RNA in the respiratory tract challenges existing knowledge.
• Highlights the critical importance of genotyping all measles virus detections to distinguish between wild-type and vaccine strains.
• Underscores the need for further investigation into whether persistent MeVV RNA signifies viable virus and its potential for transmission.