Reliable quantification of plasma HDV RNA is of paramount importance for treatment monitoring: A European multicenter study

•When using a commercially available kit for quantitation of HDV RNA, it is strongly recommended to follow the procedures validated by the manufacturer.•In case of any modification of a validated extraction and amplification/detection protocol, determination of the specific correction factor is required to guarantee comparable results.•Correction factors for different laboratory settings can easily be calculated utilizing the 1st WHO international standard for HDV RNA, leading to harmonization of quantitative results.