Laboratory Modeling of SARS-CoV-2 Exposure Reduction Through Physically Distanced Seating in Aircraft Cabins Using Bacteriophage Aerosol — November 2020

Abstract

On April 14, 2021, this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr).Aircraft can hold large numbers of persons in close proximity for long periods, which can increase the risk for transmission of infectious disease.* Current CDC guidelines recommend against travel for persons who have not been vaccinated against COVID-19, and a January 2021 CDC order requires masking for all persons while on airplanes. †, § Research suggests that seating proximity on aircraft is associated with increased risk for infection with SARS-CoV-2, the virus that causes COVID-19 (1,2). However, studies quantifying the benefit of specific distancing strategies to prevent transmission, such as keeping aircraft cabin middle seats vacant, are limited. Using bacteriophage MS2 virus as a surrogate for airborne SARS-CoV-2, CDC and Kansas State University (KSU) modeled the relationship between SARS-CoV-2 exposure and aircraft seating proximity, including full occupancy and vacant middle seat occupancy scenarios. Compared with exposures in full occupancy scenarios, relative exposure in vacant middle seat scenarios was reduced by 23% to 57% depending upon the modeling approach. A 23% exposure reduction was observed for a single passenger who was in the same row and two seats away from the SARS-COV-2 source, rather than in an adjacent middle seat. When quantifying exposure reduction to a full 120-passenger cabin rather than to a single person, exposure reductions ranging from 35.0% to 39.4% were predicted. A 57% exposure reduction was observed under the vacant middle seat condition in a scenario involving a three-row section that contained a mix of SARS-CoV-2 sources and other passengers. Based on this laboratory model, a vacant middle seat reduces risk for exposure to SARS-CoV-2 from nearby passengers. These data suggest that increasing physical distance between passengers and lowering passenger density could help reduce potential COVID-19 exposures during air travel. Physical distancing of airplane passengers, including through policies such as middle seat vacancy, could provide additional reductions in SARS-CoV-2 exposure risk.The study consisted of three components. The first involved analysis of data on virus aerosol dispersion in aircraft cabin mock-ups from a previous study conducted at KSU during *

Identifying mitigation strategies for COVID-19 superspreading on flights using models that account for passenger movement

“…Airlines have discontinued such practices as air travel increased in recent months [ 25 ]. A recent study suggested that keeping middle seats empty lowers exposure (dose) significantly [ 26 ]. But it did not calculate the infection risk, account for passenger movement, or study the impact of masks.…”

“…Following PRCC methodology described in Refs. [ 26 , 27 ], we rank the uncertain parameters, κ and d 0 , in the sampling matrix together with the outcome measures. The PRCC measures the effect of each input parameter on outcome variable, assuming the parameters to be independent.…”

Effects of nanosized water droplet generation on number concentration measurement of virus aerosols when using an airblast atomizer

“…Given that many of the routine laboratory procedures used to study and process virus samples (sample de-capping, pipetting, centrifugation, and mixing) exhibit high potential for producing aerosols 13 , 17 , 18 , it is important to adopt strict safety precautions when artificially aerosolizing virus particles using atomizers. Hence, it is preferable to generate aerosolized viruses at low concentrations to reduce health risks 16 , 19 and mimic the actual environment in which airborne virus particles are present as low concentrations 20 , 21 . Several studies indicate that SMPS results are affected by particle shape and morphology and by the upper and lower size limits set by the instrument 5 , 6 , 22 .…”

Assessment of a Biosafety Device to Control Contamination by Airborne Transmission during Orthodontic/Dental Procedures

“…In order to access small particles in the aerosol contamination, a bacteriophage for Escherichia coli previously isolated from domestic sewage samples was used [ 16 ]. The choice of a bacteriophage as a contamination model is due to its similar size to SARS-CoV-2 [ 17 ] and because this microorganism is harmless to humans.…”