Increased risk of hospitalisation and intensive care admission associated with reported cases of SARS-CoV-2 variants B.1.1.7 and B.1.351 in Norway, December 2020 –May 2021

Abstract

Introduction Since their emergence, SARS-CoV-2 variants of concern (VOC) B.1.1.7 and B.1.351 have spread worldwide. We estimated the risk of hospitalisation and admission to an intensive care unit (ICU) for infections with B.1.1.7 and B.1.351 in Norway, compared to infections with non-VOC. Materials and methods Using linked individual-level data from national registries, we conducted a cohort study on laboratory-confirmed cases of SARS-CoV-2 in Norway diagnosed between 28 December 2020 and 2 May 2021. Variants were identified based on whole genome sequencing, partial sequencing by Sanger sequencing or PCR screening for selected targets. The outcome was hospitalisation or ICU admission. We calculated adjusted risk ratios (aRR) with 95% confidence intervals (CIs) using multivariable binomial regression to examine the association between SARS-CoV-2 variants B.1.1.7 and B.1.351 with i) hospital admission and ii) ICU admission compared to non-VOC. Results We included 23,169 cases of B.1.1.7, 548 B.1.351 and 4,584 non-VOC. Overall, 1,017 cases were hospitalised (3.6%) and 206 admitted to ICU (0.7%). B.1.1.7 was associated with a 1.9-fold increased risk of hospitalisation (aRR 95%CI 1.6–2.3) and a 1.8-fold increased risk of ICU admission (aRR 95%CI 1.2–2.8) compared to non-VOC. Among hospitalised cases, no difference was found in the risk of ICU admission between B.1.1.7 and non-VOC. B.1.351 was associated with a 2.4-fold increased risk of hospitalisation (aRR 95%CI 1.7–3.3) and a 2.7-fold increased risk of ICU admission (aRR 95%CI 1.2–6.5) compared to non-VOC. Discussion Our findings add to the growing evidence of a higher risk of severe disease among persons infected with B.1.1.7 or B.1.351. This highlights the importance of prevention and control measures to reduce transmission of these VOC in society, particularly ongoing vaccination programmes, and preparedness plans for hospital surge capacity.

No difference in risk of hospitalization between reported cases of the SARS-CoV-2 Delta variant and Alpha variant in Norway

“…In this study, we have analysed individual-level data on laboratory-confirmed cases of COVID-19 in Norway and hospitalisations among cases within the study period, as well as demographic characteristics, vaccination status and underlying comorbidities. Earlier analyses of other VOC in Norway showed an increased risk of hospitalisation for Alpha and Beta compared to non-VOC (Veneti et al, 2021), in line with others (Bager et al, 2021a;Funk et al, 2021;Grint et al, 2021;Fisman and Tuite, 2021). Here our findings indicate no difference in the risk of hospitalisation for SARS-CoV-2 cases infected with the Delta variant compared to the Alpha variant in Norway, in contrast to published estimates from other countries.…”

“…Alpha has been shown to be more easily transmitted than non-VOC variants (Davies et al, 2021), and was the dominant circulating SARS-CoV-2 variant in Norway during the third wave of infections in the winter and spring of 2021. It was also associated with a 1.9-fold increased risk of hospitalisation compared to non-VOC variants (Veneti et al, 2021). Similar associations were observed in other European countries (Bager et al, 2021a;Funk et al, 2021;Grint et al, 2021).…”

“…Model selection for the multivariable binomial regression was conducted using the likelihood ratio test and the Akaike Information Criterion. We kept the variables variant (due to the main aim of the study) and sex (demographic characteristic associated with risk of hospitalisation in previous analyses in Norway (Veneti et al, 2021)) in our multivariable analysis, even if they were not significant. We also checked for interactions between all our co-variates by including interaction terms in our models.…”

The Disease Severity and Clinical Outcomes of the SARS-CoV-2 Variants of Concern

“…In addition, the differences in the risk of mortality mainly came from Funk et al (31) and Martínez-García et al (43) wherein they concluded that the mortality rate was reduced, and Stirrup et al (49) concluded that the mortality rate was equivalent. For the Beta variant compared to wildtype virus, Funk et al (31), Fisman and Tuite, (35), and Veneti et al (46) found that it increased the risk of hospitalization and ICU admission. In addition, Funk et al (31) and Fisman and Tuite, (35) reported that Beta variant also increased the risk of mortality.…”

Interactions of SARS-CoV-2 protein E with cell junctions and polarity PDZ-containing proteins

“…Less prevalent than the alpha and delta variants, the beta variant accounted for approximately 10% of virus samples in France in June 2021 (https://www.santepubliquefrance.fr/). Mutations in the beta variant make it more transmissible, with greater antibody resistance, higher risk of hospitalization, ICU admission, and death compared to earlier SARS-CoV-2 E variants (Veneti et al, 2021; Wang et al, 2021). In addition to the P71L mutation, the beta variant has other mutations, including three on its spike protein, which may help the virus to escape antibodies and to bind more tightly to human cells (Han et al, 2021).…”