The Supplementary appendix is here:
https://www.thelancet.com/cms/10.1016/S2666-5247(20)30003-3/attachment/34ed069e-7268-42ae-8627-df3aa869d81b/mmc1.pdf
That’s what I was looking at. I don’t see a temperature given for the surface & materials comparisons. I’d guess room temp.