[Correspondence] Increased risk of hospitalisation and death with the delta variant in the USA

Increased hospitalisation risk with SARS-CoV-2 delta (B.1.617.2) variant infection compared with alpha (B.1.1.7) variant infection in unvaccinated people was reported by Katherine Twohig and colleagues in the UK (hazard ratio [HR] 2·32 [95% CI 1·29–4·16])1 and Peter Bager and colleagues in Denmark (3·01 [2·02–4·50]).2 To corroborate these results in the USA, as well as to examine risk of intensive care unit (ICU) admission or death, we analysed a large cohort of unvaccinated COVID-19 cases within the Veterans Health Administration (VHA) using the previously described COVID-19 Shared Data Resource.