COVID-19: A case for the collection of race data in Canada and abroad.

Racialized populations have consistently been shown to have poorer health outcomes worldwide. This pattern has become even more prominent in the wake of the coronavirus disease 2019 (COVID-19) pandemic. In countries where race disaggregated data are routinely collected, such as the United States and the United Kingdom, preliminary reports have identified that racialized populations are at a heightened risk of COVID-19 infection and mortality. Similar patterns are emerging in Canada but rely on proxy measures such as neighbourhood diversity to account for race, in the absence of person-level data. It follows that the collection of race disaggregated data in Canada is a crucial element in identifying individuals at risk of poorer COVID-19 outcomes and developing targeted public health interventions to mitigate risk among Canada's racialized populations. Given this continuing gap, advocating for timely access to this data is of great importance owing to the challenges that the COVID-19 pandemic has highlighted amongst racialized populations in Canada and worldwide.

Serum antibody response in COVID-19-recovered patients who retested positive.

BACKGROUND: Research studies comparing antibody response from coronavirus disease 2019 (COVID-19) cases that retested positive (RP) using reverse transcription polymerase chain reaction (RT-PCR) and those who did not retest positive (NRP) were used to investigate a possible relationship between antibody response and retesting status. METHODS: Seven data bases were searched. Research criteria included cohort and case-control studies, carried out worldwide and published before September 9, 2020, that compared the serum antibody levels of hospitalized COVID-19 cases that RP after discharge to those that did NRP. RESULTS: There is some evidence that immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody levels in RP cases were lower compared with NRP cases. The hypothesis of incomplete clearance aligns with these findings. The possibility of false negative reverse transcription polymerase chain reaction (RT-PCR test results during viral clearance is also plausible, as concentration of the viral ribonucleic acid (RNA) in nasopharyngeal and fecal swabs fluctuate below the limits of RT-PCR detection during virus clearance. The probability of reinfection was less likely to be the cause of retesting positive because of the low risk of exposure where cases observed a 14 day-quarantine after discharge. CONCLUSION: More studies are needed to better explain the immune response of recovered COVID-19 cases retesting positive after discharge.

Assessing the progression of the COVID-19 pandemic in Canada using testing data and time-dependent reproduction numbers.

OBJECTIVES: To compare a mathematical tool and time-dependent reproduction number (Rt) estimates to assess the COVID-19 pandemic progression in a Canadian context. METHODS: Total number of reported cases were plotted against total number of tests for COVID-19 performed over time, with and without smoothing, for Canada and some Canadian provinces individually. Changes in curvature profile were identified as either convex or concave as indicators of pandemic acceleration or deceleration, respectively. Rt estimates were calculated on an exponential growth rate. RESULTS: For Canada as a whole, the testing graphs had a slightly concave profile and a coincident decrease in Rt estimates. Saskatchewan more recently had a convex profile with a gradual shift to a concave profile and also demonstrated a gradual decline in Rt estimates. Curves and Rt estimates for Alberta, British Columbia, Manitoba, Nova Scotia, Ontario and Quebec displayed a gradual shift towards concavity over time and an overall decrease in Rt estimates, which is suggestive of a positive impact of public health interventions implemented federally and provincially. CONCLUSION: The present analyses compared a mathematical tool to Rt estimates to ascertain the status of the pandemic in Canada. Caution should be taken when interpreting results due to factors such as varying testing protocols, available testing data unique to each province and limitations inherent to each method, which may generate different results using the two approaches. Analysis of testing data may complement metrics obtained from surveillance data to allow for a weight-of-evidence approach to assess the status of the COVID-19 pandemic.

RéSUMé: OBJECTIFS: Comparer un outil mathématique aux estimations du taux de reproduction en fonction du temps (Rt) pour évaluer la progression de la pandémie de la COVID-19 dans le contexte canadien. MéTHODES: Le nombre total de cas signalés a été comparé au nombre total de tests à la COVID-19 effectués au fil du temps, avec et sans lissage, pour le Canada et certaines provinces canadiennes individuellement. Les modifications du profil de courbure identifiées comme étant convexes ou concaves seraient des indicateurs respectivement d'une accélération ou d'une décélération de la pandémie. Le calcul des estimations du Rt a été réalisé en fonction du taux de croissance exponentiel. RéSULTATS: Pour l'ensemble du Canada, la légère concavité des graphiques relatifs aux tests coïncidait avec la diminution des estimations du Rt. Plus récemment, la Saskatchewan avait un profil convexe avec un passage progressif à un profil concave et a également démontré une baisse progressive des estimations du Rt. Les courbes et les estimations du Rt pour l'Alberta, la Colombie-Britannique, le Manitoba, la Nouvelle-Écosse, l'Ontario et le Québec ont montré un glissement progressif vers la concavité au fil du temps et une diminution globale des estimations du Rt, ce qui suggère un impact positif des interventions de santé publique mises en œuvre au niveau fédéral et provincial. CONCLUSION: Les présentes analyses ont comparé un outil mathématique aux estimations de Rt pour déterminer l'état de la pandémie au Canada. Les résultats doivent être interprétés avec prudence en raison de certains facteurs tels que les différences entre provinces en ce qui concerne les protocoles de réalisation des tests et la disponibilité des données relatives aux tests. De plus, une limite inhérente à la méthodologie de cette étude est la possibilité d'obtenir des résultats différents en fonction de l'approche utilisée. L'analyse des données des tests pourrait être complémentaire à celle des données de surveillance pour permettre une approche fondée sur le poids de la preuve dans le cadre de l'évaluation de l'état de la pandémie de la COVID-19.