Comment by Steven Novella

There are two types of evidence, broadly speaking, we can bring to bear on this question. The first is epidemiological – looking at the earliest cases of COVID including the strains of virus with which they were infected, and data on the virus (such as in waste water) in the local environment. This evidence is looked at through the lens of – which is more likely, a local zoonotic spillover or a lab leak. [...] It is possible we many never know for sure the exact path that this virus took to get into the human population. Such is the nature of science – we make the best inference possible with the data we have, but we rarely know anything for certain.