Most utilise the amino acid sequence of angiotensin-converting enzyme 2 (ACE2, the host receptor involved in entry of SARS-CoV-2) and base predictions on measures of similarity to human ACE2, reasoning that changes relative to this sequence (particularly at amino acid positions known to interact with the SARS-CoV-2 spike protein) decrease the probability of successful infection (Ahmed et al., 2021; Alexander et al., 2020; Damas et al., 2020; Frank et al., 2020; Kumar et al., 2021; Luan et al., 2020; Melin et al., 2020; Qiu et al., 2020). Here, ACE2 is linked to infection.