In France, RNA extraction was performed on 140 µl of the clinical sample with the QIAamp viral RNA minikit (Qiagen), following the manufacturer protocol, and stored at −80°C. IDV screening in clinical samples was performed by Quantitative reverse transcription PCR (RT-qPCR) using primers (0.8 µM of final concentration) and hydrolysis probe (0.2 µM of final concentration) as described in Hause et al. (2013) (link) using the QuantiNova probe RT-PCR kit (Qiagen, Germany). The RT-qPCR reactions were carried out on a LightCycler ninety-six real-time PCR system (Roche, Switzerland) with the following cycling conditions: 45°C for 30 min, 95°C for 15 min, followed by forty cycles at 95°C for 5 s, and 60°C for 30 s. In Italy, IDV molecular screening was carried out as described in Faccini et al. (2017) (link). In Luxembourg, RNA extraction was performed with the QIAamp viral RNA minikit (Qiagen). The presence of IDV in clinical samples was tested by real-time RT-PCRs by using the primers (0.4 µM of final concentration) and probe (0.15 µM of final concentration) as described in Hause et al. (2013) (link) using the QuantiTect probe RT-PCR kit (Qiagen). Cycling conditions were as follows: 50°C for 30 min, 95°C for 15 min, followed by forty-five cycles at 95°C for 15 s, and 60°C for 40 s.