Outbreak of delta variant SARS-CoV-2 virus on a psychogeriatric ward in Helsinki, Finland, August 2021; two-dose vaccination reduces mortality and disease severity amongst the elderly.

We describe an outbreak of delta variant SARS-CoV-2 on a psychogeriatric ward of elderly patients. Retrospectively collected data was analysed using Fisher's exact test to assess the association between patients’ vaccination status and infection rates, severity of disease and mortality. Vaccination with two doses was shown to reduce severity of disease (5% 75%, < 0.