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Objectives: The objective was to compare COVID-19 outcomes in the Omicron-driven fourth wave with prior waves in the Western Cape, assess the contribution of undiagnosed prior infection to differences in outcomes in a context of high seroprevalence due to prior infection and determine whether protection against severe disease conferred by prior infection and/or vaccination was maintained., Methods: In this cohort study, we included public sector patients aged ≥20 years with a laboratory-confirmed COVID-19 diagnosis between 14 November and 11 December 2021 (wave four) and equivalent prior wave periods. We compared the risk between waves of the following outcomes using Cox regression: death, severe hospitalisation or death and any hospitalisation or death (all ≤14 days after diagnosis) adjusted for age, sex, comorbidities, geography, vaccination and prior infection., Results: We included 5144 patients from wave four and 11,609 from prior waves. The risk of all outcomes was lower in wave four compared to the Delta-driven wave three (adjusted hazard ratio (aHR) [95% confidence interval (CI)] for death 0.27 [0.19; 0.38]. Risk reduction was lower when adjusting for vaccination and prior diagnosed infection (aHR: 0.41, 95% CI: 0.29; 0.59) and reduced further when accounting for unascertained prior infections (aHR: 0.72). Vaccine protection was maintained in wave four (aHR for outcome of death: 0.24; 95% CI: 0.10; 0.58)., Conclusions: In the Omicron-driven wave, severe COVID-19 outcomes were reduced mostly due to protection conferred by prior infection and/or vaccination, but intrinsically reduced virulence may account for a modest reduction in risk of severe hospitalisation or death compared to the Delta-driven wave., (© 2022 The Authors Tropical Medicine & International Health Published by John Wiley & Sons Ltd.)

Objectives: Reducing child mortality requires good information on its causes. Whilst South African vital registration data have improved, the quality of cause-of-death data remains inadequate. To improve this, data from death certificates were linked with information from forensic mortuaries in Western Cape Province., Methods: A local mortality surveillance system was established in 2007 by the Western Cape Health Department to improve data quality. Cause-of-death data were captured from copies of death notification forms collected at Department of Home Affairs Offices. Using unique identifiers, additional forensic mortuary data were linked with mortality surveillance system records. Causes of death were coded to the ICD-10 classification. Causes of death in children under five were compared with those from vital registration data for 2011., Results: Cause-of-death data were markedly improved with additional data from forensic mortuaries. The proportion of ill-defined causes was halved (25-12%), and leading cause rankings changed. Lower respiratory tract infections moved above prematurity to rank first, accounting for 20.8% of deaths and peaking in infants aged 1-3 months. Only 11% of deaths from lower respiratory tract infections occurred in hospital, resulting in 86% being certified in forensic mortuaries. Road traffic deaths increased from 1.1-3.1% (27-75) and homicides from 3 to 28., Conclusions: The quality and usefulness of cause-of-death information for children in the WC was enhanced by linking mortuary and vital registration data. Given the death profile, interventions are required to prevent and manage LRTI, diarrhoea and injuries and to reduce neonatal deaths., (© 2015 John Wiley & Sons Ltd.)