COVID-19 infections following outdoor mass gatherings in low incidence areas: retrospective cohort study
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Abstract
Objective
Indoor mass gatherings in counties with high COVID-19 incidence have been linked to infections. We examined if outdoor mass gatherings in counties with low COVID-19 incidence are also followed by infections.
Methods
We retrospectively examined COVID-19 incidence in 20 counties that held mass gathering rallies (19 outdoor and 1 indoor) in the United States in August-September 2020. They were compared to the rest of the United States counties. We utilized a 7-day moving average and compared the change on the gathering date and 15 days later, based on the 95% confidence interval. For control counties we used the median of the gathering dates.
Setting
The United States
Population
8.4 million in the counties holding mass gatherings, and 324 Million in the rest of the counties in the United States.
Main Outcome Measure
Change in COVID-19 incidence rate per 100,000 capita during the two weeks following mass gatherings.
Results
In the two weeks following the gatherings, the COVID-19 incidence increased significantly in 14 of 20 counties. The county with the highest incidence increase (3.8-fold) had the 2 nd lowest incidence before the gathering. The county with the highest decrease (0.4-fold) had the 3 rd highest incidence before the gathering. At the gathering date, the average incidence of counties with gatherings was lower than the rest of the United States, and after the gathering, it increased 1.5-fold, while the rest of the United States increased 1.02-fold.
Conclusion
These results suggest that even outdoor gatherings in areas with low COVID-19 incidence are followed by increased infections, and that further precautions should be taken at such gatherings.
What is already known on the topic
Mass gatherings have been linked to COVID-19 infections, but it is less clear how much it happens outdoors, and in areas with low incidence.
What this study adds
COVID-19 infections increased significantly in 14 of 20 counties that held mass gathering rallies in the United States, 19 of which were outdoors. The county with the highest incidence increase (3.8-fold) was outdoors and had a low incidence before the gathering. The average incidence of all 20 counties with gatherings was lower at the gathering day compared with the rest of the United State, and it increased 1.5-fold following the gatherings. Our findings suggest a need for precautions in mass gatherings, even when outdoors and in areas with a low incidence of COVID-19.
Article activity feed
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SciScore for 10.1101/2020.10.22.20184630: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
No key resources detected.
Results from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:The main limitation of our findings is that counties that held mass gatherings during the COVID-19 pandemic might be less likely to take other COVID-19 precautions that reduce COVID-19 transmission, such as masks, and keeping a distance of 6 feet.10 There have been reports of a lack of such precautions in the analyzed mass gatherings.3 Our findings suggest that mass gatherings may increase COVID-19 incidence even when they are held …
SciScore for 10.1101/2020.10.22.20184630: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
No key resources detected.
Results from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:The main limitation of our findings is that counties that held mass gatherings during the COVID-19 pandemic might be less likely to take other COVID-19 precautions that reduce COVID-19 transmission, such as masks, and keeping a distance of 6 feet.10 There have been reports of a lack of such precautions in the analyzed mass gatherings.3 Our findings suggest that mass gatherings may increase COVID-19 incidence even when they are held outdoors and in areas with low COVID-19 incidence. Therefore, the public health consequences of such mass gatherings should be considered. If such mass gatherings continue, preventive measures, such as masks, distancing, and contact tracing, should be taken in those gatherings to limit COVID-19 infections.
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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