Aerosol Particle Size Influences the Infectious Dose and Disease Severity in a Golden Syrian Hamster Model of Inhalational COVID-19.

Significant evidence suggests that SARS-CoV-2 can be transmitted via respiratory aerosols, which are known to vary as a function of respiratory activity. Most animal models examine disease presentation following inhalation of small-particle aerosols similar to those generated during quiet breathing or speaking. However, despite evidence that particle size can influence dose-infectivity relationships and disease presentation for other microorganisms, no studies have examined the infectivity of SARS-CoV-2 contained in larger particle aerosols similar to those produced during coughing, singing, or talking.

Comparison of Dose-Response Relationships for Two Isolates of SARS-CoV-2 in a Nonhuman Primate Model of Inhalational COVID-19.

As the COVID-19 pandemic has progressed, numerous variants of SARS-CoV-2 have arisen, with several displaying increased transmissibility. The present study compared dose-response relationships and disease presentation in nonhuman primates infected with aerosols containing an isolate of the Gamma variant of SARS-CoV-2 to the results of our previous study with the earlier WA-1 isolate of SARS-CoV-2. Disease in Gamma-infected animals was mild, characterized by dose-dependent fever and oronasal shedding of virus.

Comparison of the survival of different isolates of SARS-CoV-2 in evaporating aerosols.

Numerous variants of SARS-CoV-2 with increased transmissibility have emerged over the course of the pandemic. Potential explanations for the increased transmissibility of these variants include increased shedding from infected individuals, increased environmental stability, and/or a lower infectious dose. Upon exhalation of a respiratory particle into the environment, water present in the particle is rapidly lost through evaporation, resulting in a decrease in particle size.

Seroconversion and fever are dose-dependent in a nonhuman primate model of inhalational COVID-19.

While evidence exists supporting the potential for aerosol transmission of SARS-CoV-2, the infectious dose by inhalation remains unknown. In the present study, the probability of infection following inhalation of SARS-CoV-2 was dose-dependent in a nonhuman primate model of inhalational COVID-19. The median infectious dose, assessed by seroconversion, was 52 TCID50 (95% CI: 23-363 TCID50), and was significantly lower than the median dose for fever (256 TCID50, 95% CI: 102-603 TCID50), resulting in a group of animals that developed an immune response post-exposure but did not develop fever or other clinical signs of infection.

The Stability of an Isolate of the SARS-CoV-2 B.1.1.7 Lineage in Aerosols Is Similar to 3 Earlier Isolates.

Background: Our laboratory previously examined the influence of environmental conditions on the stability of an early isolate of SARS-CoV-2 (hCoV-19/USA/WA-1/2020) in aerosols generated from culture medium or simulated saliva. However, genetic differences have emerged among SARS-CoV-2 lineages, and it is possible that these differences may affect environmental stability and the potential for aerosol transmission.

Methods: The influence of temperature, relative humidity, and simulated sunlight on the decay of 4 SARS-CoV-2 isolates in aerosols, including 1 belonging to the recently emerged B.