# Screening of wild roe deer populations in Sweden 2016–2022 for SARS-CoV-2

## TL;DR

This study tested Swedish roe deer for SARS-CoV-2 from 2016 to 2022 and found no evidence of the virus, supporting the idea that spill-over is rare in Europe.

## Contribution

First SARS-CoV-2 screening in Swedish roe deer using retropharyngeal lymph node samples.

## Key findings

- All 110 tested roe deer samples were negative for SARS-CoV-2 RNA.
- Results align with European trends showing limited spill-over into wild deer.
- Contrasts with North American findings where deer show high infection rates.

## Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic with significant human impact and zoonotic concerns. In North America, white-tailed deer (Odocoileus virginianus) show high prevalence of infection and viral mutations, raising concerns about novel variants and reverse zoonosis. The World Organisation for Animal Health (WOAH) stated that cervids could become silent reservoirs, urging global surveillance. In Europe, studies have not found significant spill-over into wild deer populations, with negative results in red, roe, fallow, and other deer species across Poland, Germany, Austria, and the UK. However, seropositivity was recently detected in urban fallow deer in Ireland. To assess SARS-CoV-2 presence in Swedish roe deer (Capreolus capreolus), retropharyngeal lymph nodes from 110 individuals (2016–2022) were tested for viral nucleic acid. All samples were negative, suggesting limited or no spill-over in Sweden. These findings align with broader European data but contrast with North American trends, highlighting the importance of continued wildlife monitoring.

•First SARS-CoV-2 screening in Swedish roe deer (Capreolus capreolus).•110 retropharyngeal lymph node samples tested from 2016 to 2022.•All samples negative for viral RNA, indicating no spill-over detected.•Results align with European trend, contrasting North American findings.•Emphasizes need for ongoing wildlife surveillance in Sweden.

First SARS-CoV-2 screening in Swedish roe deer (Capreolus capreolus).

110 retropharyngeal lymph node samples tested from 2016 to 2022.

All samples negative for viral RNA, indicating no spill-over detected.

Results align with European trend, contrasting North American findings.

Emphasizes need for ongoing wildlife surveillance in Sweden.