How did someone in Antarctica catch a cold? If it might not be knowable, why would that prove 1 person can get Covid by staying home?
I guess the most likely case is that the virus stayed intact somewhere on a surface, and after some time some human touched it.
This doesn't negate that staying at home decreases your chance of getting infected by a lot.
Looking at the paper: "...symptoms and signs of a common cold after 17 weeks of complete isolation. Examination of specimens taken from the men in relation to the outbreak has not revealed a causative agent."
Symptoms of a common cold can be caused by several problems, not necessarily a bug?
Depends on what symptoms.
Head ache, nausea, diarrhea, vomiting, that probably yes.
Coughing, runny nose, throat infection, swollen lymph nodes, that less.
That said, the paper is pretty old, and we have now better techniques.
At that time, the method which we use now to detect viruses was not even invented (PCR, 1980s), and even with that, you can only find what you're looking for.
If they'd re-examine the samples today (if properly stored), they might find something with the standard techniques, and even if not, catch-all metagenomic sequencing might find it.
