Human Source Severe Acute Respiratory Syndrome Coronavirus 2 Aerosol Transmission to Remote Sentinel Hamsters

Bioaerosol-mediated transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via building ventilation systems has yet to be convincingly demonstrated. We used the South African Airborne Infections Research (AIR) facility near Pretoria to study human-to-animal (H2A) transmission of SARS-CoV-2 in newly diagnosed patients. While the facility was built to study tuberculosis transmission, this was its first adaptation to study H2A virus transmission.

Patients with clinically confirmed coronavirus disease 2019 were housed for up to 4 days in in the AIR facility with continuously exhausting patient ward air to hamsters housed in animal exposure rooms. After a 3-week exposure period, animals were held for an additional week to allow for antibody development. Animal sera were analyzed for anti-spike and plaque reduction activities and lung samples for pathology.

Seven patients provided ≥400 in-residence hours over a 17-day period. Pair-housed naive golden Syrian hamsters (n = 216) received continuous exposure to mixed patient ward exhaust. Serum analyses revealed anti-SARS-CoV-2 immunoglobulin G in 58% of animals tested. Plaque reduction assays on 7 high-titer serum samples revealed neutralizing activity.

These results support the concept that viral bioaerosols generated from patients remain infectious over long-distance transport through a building ventilation system. The seroconversion among sentinel animals supports the long-held belief that airborne infections manifest as a stochastic rather than deterministic event that is subject to a threshold dose effect. Further confirmatory studies are necessary to characterize the relationship between the bioaerosol delivered and the infections that result in this controlled H2A transmission model.