The emergence of highly transmissible SARS-CoV-2 variants has created a need to reassess the risk posed by increasing social contacts as countries resume pre-pandemic activities, particularly in the context of resuming large-scale events over multiple days. To examine how social contacts formed in different activity settings influences interventions required to control Delta variant outbreaks, we collected high-resolution data on contacts among passengers and crew on cruise ships and combined the data with network transmission models. We found passengers had a median of 20 (IQR 10–36) unique close contacts per day, and over 60% of their contact episodes were made in dining or sports areas where mask wearing is typically limited. In simulated outbreaks, we found that vaccination coverage and rapid antigen tests had a larger effect than mask mandates alone, indicating the importance of combined interventions against Delta to reduce event risk in the vaccine era.
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Pung, R., Firth, J., Spurgin, L., Singapore CruiseSafe Working Group, CMMID COVID-19 Working Group, Lee, V. & Kucharski, A. 2022, 'Using high-resolution contact networks to evaluate SARS-CoV-2 transmission and control in large-scale multi-day events', Nature Communications, 13(1), article no: 1956. https://doi.org/10.1038/s41467-022-29522-y