Trajectories of hospitalisation for patients infected with SARS-CoV-2 variant B.1.1.7 in Norway, December 2020 – April 2021

Whittaker, Robert; Kristofferson, Anja Bråthen; Seppälä, Elina; Salamanca, Beatriz Valcárcel; Veneti, Lamprini; Storm, Margrethe Larsdatter; Bøås, Håkon; Aasand, Nina; Naseer, Umaer; Bragstad, Karoline; Kvåle, Reidar; Golestani, Karan; Feruglio, Siri Laura; Vold, Line; Nygård, Karin; Buanes, Eirik Alnes

doi:10.1016/j.jinf.2021.07.025

Cited by 6 publications

(6 citation statements)

References 9 publications

(5 reference statements)

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“…Ultimately, 26 studies that met the inclusion criteria were selected in this review for further analysis. Each study's main findings are summarized in Table 1 ( 25 – 50 ). Among the 26 studies, most were related to variant Alpha, followed by Beta, Gamma, and Delta.…”

Section: Resultsmentioning

confidence: 99%

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

Lin

Liu

Tang

et al. 2021

Front. Public Health

181

165

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With the continuation of the pandemic, many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have appeared around the world. Owing to a possible risk of increasing the transmissibility of the virus, severity of the infected individuals, and the ability to escape the antibody produced by the vaccines, the four SARS-CoV-2 variants of Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2) have attracted the most widespread attention. At present, there is a unified conclusion that these four variants have increased the transmissibility of SARS-CoV-2, but the severity of the disease caused by them has not yet been determined. Studies from June 1, 2020 to October 15, 2021 were considered, and a meta-analysis was carried out to process the data. Alpha, Beta, Gamma, and Delta variants are all more serious than the wild-type virus in terms of hospitalization, ICU admission, and mortality, and the Beta and Delta variants have a higher risk than the Alpha and Gamma variants. Notably, the random effects of Beta variant to the wild-type virus with respect to hospitalization rate, severe illness rate, and mortality rate are 2.16 (95% CI: 1.19–3.14), 2.23 (95% CI: 1.31–3.15), and 1.50 (95% CI: 1.26–1.74), respectively, and the random effects of Delta variant to the wild-type virus are 2.08 (95% CI: 1.77–2.39), 3.35 (95% CI: 2.5–4.2), and 2.33 (95% CI: 1.45–3.21), respectively. Although, the emergence of vaccines may reduce the threat posed by SARS-CoV-2 variants, these are still very important, especially the Beta and Delta variants.

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Section: Resultsmentioning

confidence: 99%

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

Lin

Liu

Tang

et al. 2021

Front. Public Health

181

165

View full text Add to dashboard Cite

show abstract

“…However, when we restricted our study population to hospitalised cases, we found no difference in the risk of ICU admission between B.1.1.7 and non-VOC. In a separate analysis, we have also found no difference in the time from symptom onset to hospitalisation, length of stay in hospital or ICU, nor odds of mortality up to 30 days post discharge for persons infected with B.1.1.7 compared to non-VOC in Norway [ 17 ]. Several studies from the UK have also found no evidence of an association between severe disease, death, and/or need for increased ICU resources among hospitalised patients infected with B.1.1.7, compared to other lineages [ 9 , 18 – 20 ].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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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.

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“…This ‘bias’ may affect the results from a number of studies, for example, the authors in. 11–22 We have proposed a simple, easily implemented sensitivity analysis. This involves a third risk: that conditional on T 0, the infection time plus a random time that is independent of the outcome.…”

Section: Discussionmentioning

confidence: 99%

“…Numerous studies have compared the risks of hospitalisation, intensive care unit admission and/or death in individuals infected with two variants of SARS-Cov-2 (either Alpha vs. pre-existing non-Alpha or Delta vs. Alpha), adjusting for calendar time of positive test, for example, the authors in. [11][12][13][14][15][16][17][18][19][20][21][22] In all these studies, the incidence of one variant has been rising while the incidence of the other has been falling or has been rising at a slower rate.…”

Section: Introductionmentioning

confidence: 99%

Adjusting for time of infection or positive test when estimating the risk of a post-infection outcome in an epidemic

Seaman

Nyberg

Overton

et al. 2022

Stat Methods Med Res

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When comparing the risk of a post-infection binary outcome, for example, hospitalisation, for two variants of an infectious pathogen, it is important to adjust for calendar time of infection. Typically, the infection time is unknown and positive test time used as a proxy for it. Positive test time may also be used when assessing how risk of the outcome changes over calendar time. We show that if time from infection to positive test is correlated with the outcome, the risk conditional on positive test time is a function of the trajectory of infection incidence. Hence, a risk ratio adjusted for positive test time can be quite different from the risk ratio adjusted for infection time. We propose a simple sensitivity analysis that indicates how risk ratios adjusted for positive test time and infection time may differ. This involves adjusting for a shifted positive test time, shifted to make the difference between it and infection time uncorrelated with the outcome. We illustrate this method by reanalysing published results on the relative risk of hospitalisation following infection with the Alpha versus pre-existing variants of SARS-CoV-2. Results indicate the relative risk adjusted for infection time may be lower than that adjusted for positive test time.

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Trajectories of hospitalisation for patients infected with SARS-CoV-2 variant B.1.1.7 in Norway, December 2020 – April 2021

Cited by 6 publications

References 9 publications

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

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

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

Adjusting for time of infection or positive test when estimating the risk of a post-infection outcome in an epidemic

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