Risk factors for community transmission of SARS-CoV-2. A cross-sectional study in 116,678 people
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Abstract
Background
The risk factors for SARS-CoV-2 transmission are not well characterised in Western populations. We sought to identify potential risk factors for transmission and actionable information to prevent for SARS-CoV-2.
Methods
Individuals tested for SARS-CoV-2 at four major laboratories were invited. In addition, participants were sampled by convenience after a media campaign. Self-reported test results were compared with laboratory results, demographic data and behavioural facts were collected using a digital platform. In a cross-sectional design positive cases were compared with negative and untested control groups.
Findings
Approximately 14 days after a countrywide lockdown in Norway, 116,678 participants were included. Median age was 46 years, 44% had children in preschool or in school; 18% were practicing health professionals. International flights, contact with infected, and gatherings of more than 50 people, were associated with high risk. Health professionals who used public transport were at higher risk of testing positive than those who did not. Having undergone light infections, the last six months was strongly associated with lower odds ratio of SARS-CoV-2 positivity. Contact with children, use of hand sanitiser and use of protective gloves in private were also associated with lower odds ratio of testing positive for SARS-CoV-2.
Interpretation
Further research is needed to explore if being a parent or looking after children is associated with lower risk of SARS-CoV-2 positivity in the next phases of the pandemic. Immunological research should be done to determine the effects of prior trivial infections on SARS-CoV-2 infection. We confirm that large gatherings during the pandemic should be avoided and those who are infected, or under suspicion thereof, posed very high risks to others this population.
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SciScore for 10.1101/2020.12.23.20248514: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: Ethical considerations: The study was approved by the Norwegian ethics committee (REK 124170) and followed the Helsinki Declaration. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Software and Algorithms Sentences Resources Data was analysed using SPSS version 26 (IBM Corp, New York, USA) and Stata version 16.0 (Stata Corp LLC, Texas, USA). SPSSsuggested: (SPSS, RRID:SCR_002865)Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We …SciScore for 10.1101/2020.12.23.20248514: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: Ethical considerations: The study was approved by the Norwegian ethics committee (REK 124170) and followed the Helsinki Declaration. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Software and Algorithms Sentences Resources Data was analysed using SPSS version 26 (IBM Corp, New York, USA) and Stata version 16.0 (Stata Corp LLC, Texas, USA). SPSSsuggested: (SPSS, RRID:SCR_002865)Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:The main limitation of the study is that we tested fewer than 12.000 of the study population. Health professionals were tested widely throughout the study period. However, having COVID-19 symptoms was a pre-requisite for testing in all phases and we could only do a cross-sectional study. Due to the test policy, most of the negative controls were health professionals with other respiratory tract infections. Many other respiratory tract infections are transmitted in the same way as COVID-19. In terms of risk factors, the negative controls were therefore similar to the SARS-CoV-2 positive cases and some genuine risk factors probably did not reach significance in this comparison. We therefore included the untested group as a second control group of mostly healthy individuals. However, the difference between the untested and the background population was not determined and there are likely biases. Furthermore, less than 40% of the tested, invited individuals participated. Therefore, this study represents a conservative estimate of risk factors for SARS-CoV-2. Old age and a number of clinical conditions associated with old age are risk factors for severe disease.15 This study recruited and asked questions on a digital platform. Although more than 69% of those aged 65-70 years in Norway use the internet on average one hour per day less than five percent of the study participants were above the age of 65 years.16 We cannot preclude that they represent those who were too ill to partic...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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