Increased aerosol transmission for B.1.1.7 (alpha variant) over lineage A variant of SARS-CoV-2

Abstract

Airborne transmission, a term combining both large droplet and aerosol transmission, is thought to be the main transmission route of SARS-CoV-2. Here we investigated the relative efficiency of aerosol transmission of two variants of SARS-CoV-2, B.1.1.7 (alpha) and lineage A, in the Syrian hamster. A novel transmission caging setup was designed and validated, which allowed the assessment of transmission efficiency at various distances. At 2 meters distance, only particles <5 micrometer traversed between cages. In this setup, aerosol transmission was confirmed in 8 out of 8 (N = 4 for each variant) sentinels after 24 hours of exposure as demonstrated by respiratory shedding and seroconversion. Successful transmission occurred even when exposure time was limited to one hour, highlighting the efficiency of this transmission route. Interestingly, the B.1.1.7 variant outcompeted the lineage A variant in an airborne transmission chain after mixed infection of donors. Combined, this data indicates that the infectious dose of B.1.1.7 required for successful transmission may be lower than that of lineage A virus. The experimental proof for true aerosol transmission and the increase in the aerosol transmission potential of B.1.1.7 underscore the continuous need for assessment of novel variants and the development or preemptive transmission mitigation strategies.

Advances and gaps in SARS-CoV-2 infection models

“…It is now clear, however, that, in competition studies, at least the alpha and beta VOCs show enhanced transmission in comparison with lineage A SARS-CoV-2 in a number of models, including hamsters, ferrets, and white-tailed deer [21][22][23][24]. This attribute could be dependent, at least partially, on the presence of VOC-specific spike substitutions such as N501Y, D614G, and V367F, which improve the affinity of the SARS-CoV-2 spike protein for the human and hamster angiotensin-converting enzyme 2 (ACE2AU : PleasenotethatACE2hasbeendefinedasangiotensi…”

UV-C light completely blocks highly contagious Delta SARS-CoV-2 aerosol transmission in hamsters

“…To test the ability of UV-C light to prevent infection of naïve hamsters by naturally aspirated aerosols we employed a modified version of an aerosol transmission system described previously. 4 In this system two cages are separated by a 1250 mm X 73 mm tube resulting in a size exclusion of airborne particles ≥10 µm. The central portion of the tube is quartz enclosed in a HDPE box containing a UV-C light source (Figure 1).…”

“…1 Epidemiological and experimental data suggests that the primary mode of transmission of the virus is through airborne particles. [2][3][4] Medical countermeasures, such as vaccines and monoclonals antibody therapies were rapidly developed, but have had limited impact on the overall control of the pandemic. While the developed vaccines are highly effective against preventing sever COVID-19 and hospitalization, their transmission-blocking potential on population level appears limited.…”

Modeling Effects of Spatial Heterogeneities and Layered Exposure Interventions on the Spread of COVID-19 across New Jersey

“…Figure S7 shows the predicted median of the new/total confirmed deaths from the 21 New Jersey counties for each of the three scenarios, i.e., Baseline (scenario 1), Social Distancing without Face Masks (scenario 2), and Social Distancing with Face Masks (scenario 3). When considering the situation of practicing social distancing but without wearing face masks (scenario 2 vs. scenario 1), the model predicts that there is a 16 [IQR (14,21)] days delay of peaks, with 179 [IQR (115, 212)] deaths averted per 100,000 people. The effectiveness of social distancing in "flattening the curve" results from the significant reduction of disease transmission/exposure, according to the estimates of transmission rates shown in Figure S8.…”

“…Aerosol-based transmission of SARS-CoV-2 has been explored in several laboratory studies [13][14][15], while extensive work is ongoing to further elucidate the role of this transmission mode on the spread of the COVID-19 pandemic [16][17][18]. A wide spectrum of studies reveal multiple physical and biological process complexities associated with the aerosol transmission pathway, ranging from the role of indoor ventilation patterns [19] to different viral loads in aerosols for different variants of SARS-CoV-2 [20,21].…”