Background: In May 2026, an outbreak of Andes virus (ANDV) infection was reported among passengers and crew of the cruise ship MV Hondius. As of 27 May, 13 linked cases and three deaths had been reported, with ongoing concern about onward transmission after disembarkation.&nbsp;<br><br>Methods: We conducted a responsive analysis of the ongoing outbreak using publicly available data published by international public health bodies. We reconstructed plausible transmission chains and fitted a stochastic agent-based model of onboard transmission to estimate the probability of transmission per close contact. We then extrapolated the inferred per-contact transmissibility to mainland UK contact rates and simulated potential mainland outbreaks using a stochastic hybrid agent-compartment model.&nbsp;<br><br>Findings: The model identified a pattern of early transmission heterogeneity consistent with superspreading aboard the ship. After accounting for this heterogeneity, estimated per-contact transmissibility was low, with a median value of 0.006 (95% interval: 0.001–0.019). This corresponded to an onboard R0, defined as the expected number of infections caused by an average infected person aboard the ship, of 0.36 (95% interval: 0.11–1.24). Extrapolating to mainland UK contact rates gave a mainland R0&nbsp;of 0.19 (95% interval: 0.06–0.67), below the (R=1) threshold required for sustained transmission.&nbsp;<br><br>Interpretation: Continued control measures remain appropriate given the severity of ANDV infection, and our results do not exclude onward viral transmission if containment measures fail. However, the inferred transmissibility of ANDV in this outbreak suggests that the risk of a sustained or sizeable mainland outbreak is low.