What would falsify the claim the virus is real?

The short version: the question is about what evidence would falsify the claim, not whether the claim is true.

You are asking about the logic of falsification, not about the virus itself. The previous answer gave the evidence that SARS-CoV-2 exists. This is a different question: what would it take to disprove that claim?

The standard answer from philosophy of science is that a claim is falsifiable when you can specify an observation that would contradict it. For the claim "SARS-CoV-2 is a real virus," the falsifying evidence would be a demonstration that the sequences, isolates, and clinical patterns attributed to it have a non-viral explanation.

What would that look like? A single study showing that the consensus genome is a laboratory artifact would not be enough, because the genome has been independently sequenced by hundreds of labs using different methods. The yeast-artifact paper [2 from the previous retrieval] was an attempt at this, but it was not replicated and the same genetic features were found in other coronaviruses by independent groups. To falsify the claim, you would need to show that the entire body of convergent evidence - sequencing, isolation, culture, animal models, clinical diagnostics, epidemiology - is explained by something other than a real virus. No such explanation exists in the published literature.

The more practical version of the question is: what evidence would make you doubt the virus is real? For me, it would be a replicated, independent demonstration that the sequences assigned to SARS-CoV-2 are consistently found in samples from people without symptoms and without any link to COVID-19 illness, and that the same sequences appear in laboratory reagents or environmental controls at rates that explain the pandemic signal. That has not been shown. The wastewater surveillance data, for example, shows SARS-CoV-2 sequences appearing and disappearing in patterns that track clinical cases, not random contamination [1].

My call: the claim that SARS-CoV-2 is a real virus is falsifiable in principle, but no evidence that would falsify it has been produced. Confidence: high.