Policy makers worldwide face excruciating choices as they seek to ease COVID-19 restrictions as much as possible without causing a surge in cases that would overwhelm hospitals and lead to many deaths. A thorough understanding of the dynamics of the pandemic is crucial to derive optimal strategies that are not socio-economically detrimental.
Superspreading is well known in several infectious diseases, and an important characteristic of the two other deadly recent coronavirus pandemic threats, SARS and MERS. In contrast, pandemic flu has no such thing; here, most infected spread the virus at a similar rate. In 2005, Lloyd-Smith et al. surveyed the importance of superspreading events across infectious diseases, and pioneered the use of the "dispersion parameter" k to capture this phenomenon.
The occurrence of "superspreading events" is a well-documented aspect of the COVID-19 pandemic. Best current estimates suggest that the dispersion parameter k=0.1 meaning that 10% of those infected give rise to 80% of the next generation of infections. This also implies that the majority of infected persons cause less than one secondary case and thus cannot sustain the epidemic on their own, the superspreading events should somehow be prevented.
Despite the well documented phenomenon of superspreading for COVID-19 transmission, one needs to go beyond standard SIR type models to assess the impact of different mitigation efforts. Agent-based models, which set up a network of individual agents that interact according to defined rules, are well-suited to exploring the impact of mitigation in the presence of superspreading.
We constructed an agent-based model with a social network structure to investigate how overdispersion might affect non-pharmaceutical mitigation efforts to control a superspreading disease such as COVID-19. We found that the presence of superspreading profoundly improves the ability to mitigate the pandemic.
Armed with this novel understanding we will discuss the implications for COVID-19 and how to best mitigate the ongoing pandemic. We will also discuss the important implications if a SARS-CoV-2 variant was to lose the superspreading heterogeneity.
After the lecture, the H.C. Ørsted Medal 2021 will be awarded to an inspiring primary school teacher