A recent study has found an over-the-counter nasal spray may interfere with respiratory virus diagnostic swabs.
Northern Health, together with The University of Melbourne, Monash University and Murdoch Children’s Research Institute, conducted a study that found carrageenan-containing nasal sprays, which are commonly available over-the-counter and are marketed as having anti-viral effects, can interfere with PCR tests used to detect COVID-19 and possibly other respiratory viruses like influenza.
The study, conducted as part of a wider study investigating use of heparin to prevent COVID19, is the first study to show that like heparin, carrageenan can affect the test results, making them inaccurate or invalid if a spray containing carrageenan is used shortly before taking a nasal swab for viruses.
One of the critical components in successfully managing COVID-19 in the community is effective and accurate PCR-testing, Northern Health said.
Tests conducted as part of the study also showed that carrageenan led to incorrect test results in 80 per cent of cases, therefore potentially leading to the spread of COVID-19.
Northern Health chief medical officer and associate investigator, Professor Prahald Ho, said the findings were vital in ensuring public health safety.
“This issue, if not recognised, could lead to false negative results, which may increase the spread of the respiratory virus and affect public health,” Professor Ho said.
Inherit study co-chief investigator and divisional director of design and discovery, Professor Donald Campbell, said it is highly likely that this finding will impact on the diagnosis of any respiratory virus and further research in this is ongoing.
“The results of studies investigating the efficacy of carrageenan-based products using PCR assays should be further scrutinised,” Professor Campbell said.
