Positive results in a real-time PCR for type A influenza associated with the use of an inactivated vaccine.

The research explored an incident during the 2007 Australian equine influenza outbreak, where a real-time PCR test returned false positive results due to contamination from a vaccine. The paper emphasizes the need for separating vaccination and testing days during disease outbreaks.

Overview of the Research

• The researchers used a real-time reverse transcription polymerase chain reaction (qRT-PCR) to test for the matrix gene of type A influenza viruses during the 2007 Australian equine influenza outbreak. This testing method was employed to verify diagnosis and monitor the eradication of the virus.
• During the outbreak, horses intended for exportation were required to get vaccinated and provide individual proof of freedom from equine influenza.

The Incident

• The researchers found that, at the end of the outbreak, four horses that were set to be exported tested positive for equine influenza. This was despite the animals’ recent vaccinations.
• Upon further examination, they discovered the cause of the positive results was contamination of the samples with the vaccine used for immunization rather than the presence of the active virus.

Recommendations

• The incident raised awareness on the possibility of vaccines interfering with diagnostic testing results. Thus, the researchers highlighted the importance of separating the days of vaccination and diagnostic testing during a disease outbreak.
• Furthermore, they recommended collection of swabs for testing to precede vaccination. This protocol would minimize the chances of vaccine contamination influencing test results.

Implications

• The findings reveal potential challenges in vaccination and testing protocols during disease outbreaks. This is particularly relevant for industries that require both vaccination and disease-free certification for exports.
• The research’s recommendations offer actionable suggestions to improve diagnostic accuracy and prevent false-positive results.