Chapter 3 70 It was unclear whether the disparities identified in our initial study persisted during the second wave, prior to the roll-out of the national vaccination programme. As such, the present study compared the rate of notified SARS-CoV-2 infections, and related hospitalisation and deaths, between city districts and ethnic backgrounds in Amsterdam between 15 June 2020 and 20 January 2021. METHODS Study design and population We conducted a registry-based observational study using routinely-collected notification data. Eligible for inclusion in this study were all PCR or antigen confirmed SARS-CoV-2 infections notified to the Public Health Service (PHS) of the Amsterdam-Amstelland region, the Netherlands, between 15 June 2020 and 20 January 2021. We included only individuals residing in the municipality of Amsterdam in this study. No other inclusion criteria were applied. Data collection We extracted COVID-19 surveillance data from the Amsterdam-Amstelland COVID-19 notification database on 21 January 2021. These data included: age at notification, date of birth, sex, postal code, date of symptom onset, notification date, hospitalisation and mortality. Hospitalisation and mortality status were recorded using two different sources: (1) the notified case or their contacts during routine contact tracing, or (2) healthcare providers, usually when hospitalisation or death occurred days or weeks after initial notification. Case records were therefore updated in the notification database if healthcare providers communicated the case had been hospitalised or died as the result of COVID-19 at a later stage. As a result, all individuals with a notified infection were assumed by the PHS not to be hospitalised and not to have died as a result of COVID-19 unless explicitly informed otherwise. We matched surveillance data to registration data from the municipality database of the City of Amsterdam (BRP) to retrieve country of birth of each notified case and their parents. Outcomes We evaluated the number of notified SARS-CoV-2 infections, and related hospitalisations and deaths, overall and over time (by notification date as well as date of symptom onset). Outcomes were: notified SARS-CoV-2 infection (based on a validated positive test result,
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