Introduction

In this work, I summarize and assess the arguments for a natural origin and against a laboratory-based origin of Covid-19 presented in the Holmes et al. preprint [1]. The preprint review by Holmes et al. represents one of the most extensive compilations of arguments for a zoonotic origin and was authored by numerous experts in relevant fields. Although Holmes et al. “contend that there is substantial body of scientific evidence supporting a zoonotic origin for SARS-CoV-2” [1], I argue that all publicly available evidence and information are consistent with both natural and laboratory origin scenarios. In the absence of dispositive evidence in support of either a natural spillover or a research-related incident, it is necessary to rigorously investigate both hypotheses [2,3]. Only with more data and information can scientists confidently evaluate the likelihood of each origin hypothesis. A credible, transparent, evidence-based, and international investigation of the origin of Covid-19 is not only vital but also feasible [3–5].