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BACKGROUND: SARS-CoV-2 in exhaled aerosols is considered an important contributor to the spread of COVID-19. However, characterizing the size distribution of virus-containing aerosol particles has been challenging as high concentrations of SARS-CoV-2 in exhaled air is mainly present close to symptom onset. We present a case study of a person with COVID-19 who was able to participate in extensive measurements of exhaled aerosols already on the day of symptom onset and then for the following three days. METHODS: Aerosol collection was performed using an eight-stage impactor while the subject was breathing, talking and singing, for 30 min each, once every day. In addition, nasopharyngeal samples, saliva samples, room air samples and information on symptom manifestations were collected every day. Samples were analyzed by RT-qPCR for detection of SARS-CoV-2 RNA. RESULTS: SARS-CoV-2 RNA was detected in seven of the eight particle size fractions, from 0.34 to >8.1 µm, with the highest concentrations found in 0.94-2.8 µm particles. The concentration of SARS-CoV-2 RNA was highest on the day of symptom onset, and declined for each day thereafter. CONCLUSION: Our data showed that 90% of the exhaled SARS-CoV-2 RNA was found in aerosol particles <4.5 µm, indicating the importance of small particles for the transmission of COVID-19 close to symptom onset. These results are important for our understanding of airborne transmission, for developing accurate models and for selecting appropriate mitigation strategies.
ABSTRACT
Introduction: Alpha-1-antitrypsin (AAT) has been shown to inhibit SARS-CoV-2 cell entry and suggested as a therapeutic agent for COVID-19. Furthermore, epidemiological association of high prevalence of Alpha-1-antitrypsin deficiency (AATD) and regional severity of COVID-19-impact has been hypothesized. In our study setting, the estimated prevalence rates of mild (PI*MZ, PI*SS or PI*MS) and moderate-to-severe AATD (PI*ZZ or PI*SZ) are high, 9% and 0.2%, respectively. Our primary aim was to examine the prevalence rate of AATD among hospitalized COVID-19-patients. Methods: In this prospective observational study, enrollment occurred from December 2020 to January 2021 in two COVID-19-units at Skåne University Hospital, Lund, Sweden. Case definition was a patient hospitalized due to COVID-19. Patients were screened for AATD with PI-typing and if results were inconclusive, PCR for the S- and Z-genes were performed. Patients were categorized as severe or moderate COVID-19 and 30-day-mortality data were collected. The primary outcome was prevalence rate of AATD. The secondary outcome investigated association between presence of mild AATD and severe COVID-19. Results: We enrolled 61 patients with COVID-19. Two patients out of 61 (3%) had mild AATD (PI*MZ) and none had moderate-to-severe AATD. 30/61 (49%) had severe COVID-19. Both patients with mild AATD developed severe COVID-19. Yet, presence of AATD was not significantly associated with severe COVID-19 (p=0.24). Conclusion: Mild AATD (PI*MS or PI*MZ) was rare in a small cohort of hospitalized patients with COVID-19 in a study setting with a high background prevalence of AATD.
ABSTRACT
BACKGROUND: Coronavirus disease 2019 (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 February-March 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 2-stage cyclone, and all samples were analyzed by RT-qPCR for severe acute respiratory syndrome coronavirus 2 (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 1 aerosol sample from 19 of 38 (50%) included cases. The odds ratio (OR) of finding positive aerosol samples decreased with each day from symptom onset (OR 0.55, 95 confidence interval [CI] .30-1.0, Pâ =â .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%) (χ2 test, Pâ =â .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.
Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Family Characteristics , Humans , RNA, Viral , Respiratory Aerosols and DropletsABSTRACT
BACKGROUND: In health care workers SARS-CoV-2 has been shown to be an occupational health risk, often associated with transmission between health care workers. Yet, insufficient information on transmission dynamics has been presented to elucidate the precise risk factors for contracting SARS-CoV-2 in this group. METHODS: In this cross-sectional study, we investigated association between questionnaire answers on potential exposure situations and SARS-CoV-2-positivity. Health care workers with and without COVID-19-patient contact at nine units at Skåne University Hospitals in Malmö and Lund, Sweden and university employees from Lund University, Sweden were enrolled. To limit impact of health care worker to health care worker transmission, units with known outbreaks were excluded. A SARS-CoV-2-positive case was defined by a previous positive PCR or anti-SARS-CoV-2 IgG in the ZetaGene COVID-19 Antibody Test. RESULTS: SARS-CoV-2-positivity was detected in 11/51 (22%) health care workers in COVID-19-units, 10/220 (5%) in non-COVID-19-units and 11/192 (6%) University employees (p = .001, Fischer's exact). In health care workers, SARS-CoV-2-positivity was associated with work in a designated COVID-19-unit (OR 5.7 (95CI 2.1-16)) and caring for COVID-19-patients during the majority of shifts (OR 5.4 (95CI 2.0-15)). In all participants, SARS-CoV-2-positivity was associated with a confirmed COVID-19 case (OR 10 (95CI 2.0-45)) in the household. CONCLUSION: Our study confirmed previous findings of elevated risk of acquiring SARS-CoV-2 in health care workers in COVID-19-units, despite exclusion of units with known outbreaks. Interestingly, health care workers in non-COVID-19-units had similar risk as University employees. Further measures to improve the safety of health care workers might be needed.KEY POINTSPrevious findings of elevated risk of contracting SARS-CoV-2 in health care workers with COVID-19 patient contact was confirmed, despite exclusion of wards with known SARS-CoV-2 outbreaks. Further measures to improve the safety of health care workers might be needed.