Risk of hospitalisation associated with infection with SARS-CoV-2 lineage B.1.1.7 in Denmark: an observational cohort study

SPS commentary:

In the study, 1944 (6·4%) individuals had a COVID-19 hospitalisation and of these, 571 (29·4%) had a B.1.1.7 infection and 1373 (70·6%) had an infection with other SARS-CoV-2 lineages.

 

According to a commentary, these findings are consistent with early reports and strengthen the association between B.1.1.7 and increased disease severity observed previously. Particularly increased severity observed with B.1.1.7 appeared to be specific to adults older than 30 years, and pronounced among those older than 65 years. It notes that the study highlights three key considerations when trying to attribute an increase in disease severity to a variant of concern that also increases transmission risk, in the context of surveillance data. First, potential confounders in this context include factors that increase acquisition risk overlapping with factors known to increase severity, irrespective of lineages, such as age or comorbidities. Second, selection biases can play a major role in drawing inference on relative severity risks. Third, increased transmission potential means that the lineage can take over and thus, some studies might be limited in comparing B.1.1.7 cases with historical cases of other lineages

 

Also published in the journal are data on mortality and critical care unit admission associated with the SARS-CoV-2 lineage B.1.1.7 in England from an observational cohort study. This showed that patients with lineage B.1.1.7 were at increased risk of CCU admission and 28-day mortality compared with patients with non-B.1.1.7 SARS-CoV-2. The primary care cohort included 198,420 patients with SARS-CoV-2 infection. Of these, 117 926 (59·4%) had lineage B.1.1.7, 836 (0·4%) were admitted to CCU, and 899 (0·4%) died within 28 days. The critical care cohort included 4272 patients admitted to CCU. Of these, 2685 (62·8%) had lineage B.1.1.7 and 662 (15·5%) died at the end of critical care. In the primary care cohort, the adjusted hazard ratios (HRs) were 2·15 (95% CI 1·75–2·65) for CCU admission and 1·65 (1·36–2·01) for 28-day mortality for patients with lineage B.1.1.7 compared with the non-B.1.1.7 group. For patients receiving critical care, mortality appeared to be independent of virus strain.