Minimised SARS-CoV-2 transmission during Tokyo 2020 Olympic and Paralympic Games: insights from enhanced integrated surveillance, Japan, July to September 2021

BACKGROUNDAmid the COVID-19 pandemic, stringent public health measures were taken during the Tokyo 2020 Olympic and Paralympic Games (Tokyo 2020).AIMWe describe SARS-CoV-2 transmission among Games participants and in-person contributors (GPIPC)s.METHODSTokyo 2020-related SARS-CoV-2 infection cases were individuals linked to the event, testing positive for the virus between 1 July-19 September 2021, reported to the Tokyo Metropolitan Government. Attack rates among athletes and team officials were determined. Enhanced case-based surveillance integrating genomic sequencing data supported viral spread investigations among various GPIPC groups.RESULTSA total 804 cases (median age: 35 years, interquartile range (IQR): 27-45; 194 female/610 male) were reported. Among athletes and team officials, attack rates were 0.6% (65/11,400) in Olympic Games and 0.6% (30/4,800) in Paralympic Games. These 95 infections concerned mainly overseas travellers (n = 92), 85 of whom were diagnosed within 14 days of arrival in Japan. Among the 804 cases, whole-genome sequencing data were obtained for 304 (median age: 38 years, IQR: 29-47; 67 female/237 male) with sufficient viral load (as indicated by RT-PCR Cq ≤ 32), including 79% (75/95) of athletes and team officials cases, 74% (131/176) of Games' organisers and media cases, and ˂ 20% (98/533) of remaining cases. Delta variants dominated (94%; 285/304), with domestic (AY.29 lineage) Delta strains prominent among Delta-variant-affected resident cases (96%; 104/108) and Games' organisers and media cases diagnosed ≥ 15 days after entering Japan (97%; 63/65). Overseas Delta strains mostly affected travellers within 14 days of entry, particularly athletes and team officials (97%; 66/68) and Games' organisers and media (29/34).CONCLUSIONMultilayered-risk-reduction measures likely minimised SARS-CoV-2 transmission to athletes.