Figure 1:

Study populations. The whole population at risk contains all those receiving hemodialysis (in-center) during the observation period at any of the seven London nephrology centers. Weekly PCR screening was carried out in this population, with additional PCR testing as indicated by symptoms or contact with a case. The main study population (gray shading) contains all SARS-CoV-2 infections, defined by positive PCR (in any setting) during the observation period, and is used to assess the risk of severe disease in those with infection. The supplementary study population (striped shading) contains a subset of the whole population at risk, comprising one nephrology center, for whom full vaccination data were available, and is only used to assess the risk of developing infection. ^aWithin 14 days of positive PCR. ^bWithin 28 days of positive PCR.