What do you mean by "probably"? My understanding is that it's unquestionably contamination, since no one is suggesting the virus was actually in Antarctic soil.

What do you mean by "probably"? My understanding is that it's unquestionably contamination, since no one is suggesting the virus was actually in Antarctic soil. The only question is the provenance of the contaminating sample, the likely possibilities being: 1. Virus cultured in a lab, in monkey or hamster cells but with virus originating from a human patient. This wouldn't be evidence of lab origin of the virus. It would still show that China is concealing important facts about the early origin of the pandemic though, since the recovered viral genome is among the most ancestral (closest to the closest-known bat viruses) known. It should thus have been scientifically noteworthy enough to publish, but that genome was unpublished until these Hungarians dug it out. 2. Virus cultured as part of a scientific experiment, before the beginning of the pandemic. That would be the "smoking gun", but nothing yet allows us to distinguish between this and case (1). Sangon Biotech's customer records might answer this, since they know when the sample was sequenced and what other customers' samples were sequenced around the same time. Those aren't too easy to get, though. I've seen speculation that Illumina's cloud services may contain significant information within reach of American subpoena, but no concrete action. Other comments speculate that an infected lab technician could explain the reads, but that wouldn't explain the hamster and monkey DNA.