Purported quantitative support for multiple introductions of SARS-CoV-2 into humans is an artefact of an imbalanced hypothesis testing framework

TL;DR

The paper critiques a previous study claiming multiple SARS-CoV-2 introductions into humans, showing that the support was due to an imbalanced hypothesis testing framework rather than actual evidence.

Contribution

It reveals that the purported support for multiple introductions was an artefact of biased hypothesis testing, emphasizing the importance of balanced model comparisons.

Findings

Support for multiple introductions disappears under balanced testing conditions

The original claim was confounded by an imbalance in hypothesis testing

Proper testing shows no substantial evidence for multiple SARS-CoV-2 introductions

Abstract

A prominent report claimed substantial support for two introductions of SARS-CoV-2 into humans using a calculation that combined phylodynamic inferences and epidemic models. Inspection of the calculation identifies an imbalance in the hypothesis testing framework that confounds this result; the single-introduction model was tested against more stringent conditions than the two-introduction model. Here, I show that when the two-introduction model is tested against the same conditions, the support disappears.