Antibodies to SARS-CoV-2 were detected in 33% of the 481 samples collected from January 2020 through 2021. None of the deer populations surveyed showed signs of clinical illness associated with SARS-CoV-2. Results of the study indicate that certain white-tailed deer populations in Illinois, Michigan, New York, and Pennsylvania were exposed to SARS-CoV-2.
It is important to note that this surveillance was designed to determine exposure of deer to SARS-CoV-2 in their natural environment. It was not designed to determine whether the deer were replicating and shedding SARS-CoV-2.
The Biorxiv preprint of the deer study does contain two interesting paragraphs that refer to Sars-CoV-2 positive tests in white tailed deer in 2019 and early 2020:
“Antibodies to SARS-CoV-2 were detected in 40% of the 2021 surveillance samples (Table 1). Antibodies were also detected in three samples from 2020 and one sample from 2019. No detections were observed in samples from 2011-2018. The results from the sVNT screening showed high concordance with those obtained by VNT (Table 1). Specifically, 24/24 of 2021 detections and 24/24 of 2021 negatives were concordant for sVNT compared to VNT.
Most of the positive samples from 2021 had percent inhibition values between 80-100% while the 2019-2020 positive samples had relatively low percent inhibition values (30.03-43.72, Figure 1). Percent inhibition scores ≥30 are considered positive for this assay. Low percent inhibition could represent potential waxing/waning immunity, non-specific antibody binding, or cross-reactivity from exposure to unknown endemic coronaviruses. The three positive samples from 2020 were collected in January, very early in the pandemic. In fact, the majority of the 2020 samples that were available for testing were from January-March, with only 21 samples collected later in the year, 20 of which were collected in October from a single location. Consequently, we have limited information on prevalence over time in 2020.