Hospital Admission and Emergency Care Risk for COVID Delta Variant

Quick Takes

  • Patients with the delta variant had more than two times the risk of hospital admission compared with patients with the alpha variant.
  • These and other data suggest that vaccination leads to a similar relative reduction in the risk of hospitalization for patients with the delta variant or the alpha variant.
  • These findings have implications for resource planning and policy decisions to mitigate the impact of the delta variant globally, in areas where the rapid spread of the delta variant might possibly occur.

Study Questions:

What is the severity of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta (B.1.617.2) variant compared with the alpha variant by determining the relative risk of hospital attendance outcomes?

Methods:

The investigators conducted a cohort study among all patients with coronavirus disease 2019 (COVID-19) in England between March 29 and May 23, 2021, who were identified as being infected with either the alpha or delta SARS-CoV-2 variant through whole-genome sequencing. Individual-level data on these patients were linked to routine health care datasets on vaccination, emergency care attendance, hospital admission, and mortality (data from Public Health England's Second Generation Surveillance System and COVID-19–associated deaths dataset; the National Immunisation Management System; and NHS Digital Secondary Uses Services and Emergency Care Data Set). The risks for hospital admission and emergency care attendance were compared between patients with sequencing-confirmed delta and alpha variants for the whole cohort and by vaccination status subgroups. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar week, and vaccination status.

Results:

Individual-level data on 43,338 COVID-19–positive patients (8,682 with the delta variant, 34,656 with the alpha variant; median age, 31 years [interquartile range, 17–43]) were included in the analysis. 196 (2.3%) patients with the delta variant versus 764 (2.2%) patients with the alpha variant were admitted to hospital within 14 days after the specimen was taken (adjusted hazard ratio [HR], 2.26 [95% CI, 1.32–3.89]). 498 (5.7%) patients with the delta variant versus 1,448 (4.2%) patients with the alpha variant were admitted to the hospital or attended emergency care within 14 days (adjusted HR, 1.45 [1.08–1.95]). Most patients were unvaccinated (32,078 [74.0%] across both groups). The HRs for vaccinated patients with the delta variant versus the alpha variant (adjusted HR for hospital admission, 1.94 [95% CI, 0.47–8.05] and for hospital admission or emergency care attendance, 1.58 [0.69–3.61]) were similar to the HRs for unvaccinated patients (2.32 [1.29–4.16] and 1.43 [1.04–1.97]; p = 0.82 for both), but the precision for the vaccinated subgroup was low.

Conclusions:

The authors concluded that this large national study found a higher hospital admission or emergency care attendance risk for patients with COVID-19 infected with the delta variant compared with the alpha variant.

Perspective:

This cohort study reports that patients with the delta variant had more than two times the risk of hospital admission compared with patients with the alpha variant. Emergency care attendance along with hospital admission was also higher for patients with the delta variant. Of note, the number of hospital attendances was low in the vaccinated subgroup, suggesting that vaccination leads to a similar relative reduction in the risk of hospitalization for patients with the delta variant or the alpha variant. These and other studies suggest that outbreaks of the delta variant in unvaccinated populations might lead to a higher health care burden compared with the previous prevalent SARS-CoV-2 strains. These findings also have implications for resource planning and policy decisions to mitigate the impact of the delta variant globally, in areas where the rapid spread of the delta variant might possibly occur.

Clinical Topics: Prevention

Keywords: Coronavirus, COVID-19, Delivery of Health Care, Disease Outbreaks, Emergency Medical Services, Emergency Service, Hospital, Immunization, Primary Prevention, Risk, SARS-CoV-2, Vaccination, Whole Genome Sequencing


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