WHO Notice for IVD User Information, 2020/05  

Primary purpose to release this notice to clear up all relevant information WHO has provided previously. It also replaced the existing WHO Information Notice for In Vitro Diagnostic Medical Device (IVD) Users’ 2020/05 version 1, issued on 14 December 2020.   

Details on the problem: WHO requested all users to pay attentions on the instructions for use (IFU) when clarifying the results for the tested samples using PCR methods. Users of IVDs should follow the IFU carefully to analyse if any manual changes made to the recommended PCR positivity threshold.   

WHO direction Analytic testing for SARS-CoV-2 suggests that cautious understanding of positive results is required (1). The cycle Threshold (Ct) is expected to distinguish infection is contrarily relative to the patient’s viral status. Where test results cannot be correlated with the scientific presentation, another example should be taken and retested using the identical or diverse NAT method.   

IVD users are reminded by WHO about the disease prevalence that changes the predictive value of test results; since disease prevalence decreases, the risk of false positive increases and it also means that the possibility of a person who receives a positive result is actually affected with SARS-CoV-2 which gets decreased as prevalence decreases, regardless of the alleged specificity.   

Most PCR evaluations are considered as an assist for investigation; thus, health care providers can consider any result in association with timing of sampling, Type of specimen, specification of assay, clinical experiences, patient record, status of any contacts, and epidemiological knowledge.   

Important IVD uses steps:  

Go through the whole IFU carefully   

Contact your local Healthcare service if any of the IFU prospect is not clear to you.  

Check each incoming consignment of IFU in order to identify any variations to the IFU.  

Mention the Ct value in the report to the requesting health care provider.