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- Alsved, Malin, et al.
(författare)
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SARS-CoV-2 in exhaled aerosol particles from covid-19 cases and its association to household transmission
- 2022
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Ingår i: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. - : Oxford University Press (OUP). - 1537-6591. ; 75:1, s. 50-56
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Covid-19 transmission via exhaled aerosol particles has been considered an important route for the spread of infection, especially during super-spreading events involving loud talking or singing. However, no study has previously linked measurements of viral aerosol emissions to transmission rates.METHODS: During Feb-Mar 2021, covid-19 cases that were close to symptom onset were visited with a mobile laboratory for collection of exhaled aerosol particles during breathing, talking and singing, respectively, and of nasopharyngeal and saliva samples. Aerosol samples were collected using a BioSpot-VIVAS and a NIOSH bc-251 two-stage cyclone, and all samples were analyzed by RT-qPCR for SARS-CoV-2 RNA detection. We compared transmission rates between households with aerosol-positive and aerosol-negative index cases.RESULTS: SARS-CoV-2 RNA was detected in at least one aerosol sample from 19 of 38 (50%) included cases. The odds ratio of finding positive aerosol samples decreased with each day from symptom onset (OR 0.55, 95CI 0.30-1.0, p=0.049). The highest number of positive aerosol samples were from singing, 16 (42%), followed by talking, 11 (30%), and the least from breathing, 3 (8%). Index cases were identified for 13 households with 31 exposed contacts. Higher transmission rates were observed in households with aerosol-positive index cases, 10/16 infected (63%), compared to households with aerosol-negative index cases, 4/15 infected (27%) (Chi-square test, p=0.045).CONCLUSIONS: Covid-19 cases were more likely to exhale SARS-CoV-2-containing aerosol particles close to symptom onset and during singing or talking as compared to breathing. This study supports that individuals with SARS-CoV-2 in exhaled aerosols are more likely to transmit covid-19.
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| 2. |
- Thuresson, Sara, et al.
(författare)
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Airborne Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Hospitals : Effects of Aerosol-Generating Procedures, HEPA-Filtration Units, Patient Viral Load, and Physical Distance
- 2022
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Ingår i: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. - : Oxford University Press (OUP). - 1537-6591. ; 75:1, s. 89-96
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Transmission of coronavirus disease 2019 (COVID-19) can occur through inhalation of fine droplets or aerosols containing infectious virus. The objective of this study was to identify situations, patient characteristics, environmental parameters, and aerosol-generating procedures (AGPs) associated with airborne severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus.METHODS: Air samples were collected near hospitalized COVID-19 patients and analyzed by RT-qPCR. Results were related to distance to the patient, most recent patient diagnostic PCR cycle threshold (Ct) value, room ventilation, and ongoing potential AGPs.RESULTS: In total, 310 air samples were collected; of these, 26 (8%) were positive for SARS-CoV-2. Of the 231 samples from patient rooms, 22 (10%) were positive for SARS-CoV-2. Positive air samples were associated with a low patient Ct value (OR, 5.0 for Ct <25 vs >25; P = .01; 95% CI: 1.18-29.5) and a shorter physical distance to the patient (OR, 2.0 for every meter closer to the patient; P = .05; 95% CI: 1.0-3.8). A mobile HEPA-filtration unit in the room decreased the proportion of positive samples (OR, .3; P = .02; 95% CI: .12-.98). No association was observed between SARS-CoV-2-positive air samples and mechanical ventilation, high-flow nasal cannula, nebulizer treatment, or noninvasive ventilation. An association was found with positive expiratory pressure training (P < .01) and a trend towards an association for airway manipulation, including bronchoscopies and in- and extubations.CONCLUSIONS: Our results show that major risk factors for airborne SARS-CoV-2 include short physical distance, high patient viral load, and poor room ventilation. AGPs, as traditionally defined, seem to be of secondary importance.
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