COVID-19 research briefs: Using public transportation or socializing in food/beverage outlets increases rates of infection

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Published: 2020-10-25 © 2020 John Wiley & Sons, Inc.

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Clinical question
Which factors increase the risk of transmission of SARS-CoV-2?

Bottom line
There was significant SARS-CoV-2 transmission among bus riders in China. People who have dined at a restaurant or visited a bar or coffee shop are more likely to have COVID-19. (LOE = 2c)

Reference
Shen Y, Li C, Dong H, et al. Community outbreak investigation of SARS-CoV-2 transmission among bus riders in eastern China. JAMA Intern Med. Published online September 01, 2020. doi:10.1001/jamainternmed.2020.5225.

Study design: Not applicable

Setting: Population-based

Synopsis
Research Brief #60: This study reports SARS-CoV-2 transmission on a bus in China on January 19, 2020. The bus ride was a round trip of 100 minutes to attend a 150-minute worship service. One man on the bus was infected but asymptomatic during the trips to and from the service. However, the individual became symptomatic with systemic and respiratory symptoms that evening after returning home. Of the other 67 individuals on the bus with him, 23 (34%) subsequently became infected. Individuals sitting closest to the index case had a slightly higher risk of infection than the other travelers. There were 60 passengers on a companion bus, and none of these individuals became infected. Both buses used air-conditioning in the recirculation mode. Among the other 172 individuals at the worship event, 7 (4.1%) subsequently received a COVID-19 diagnosis. Individuals on the infected bus were 11.4 (95% CI 5.1 - 25.4) times more likely to have COVID-19 than the other individuals who attended the worship event. Like the Chinese restaurant study, this study demonstrates a high transmission rate in an enclosed space with the air-conditioning on. Shen Y, Li C, Dong H, et al. Community outbreak investigation of SARS-CoV-2 transmission among bus riders in eastern China. JAMA Intern Med. Published online September 01, 2020. doi:10.1001/jamainternmed.2020.5225. Research Brief #61: In this case-control study, 615 potential case patients and 1212 control participants were randomly selected from those tested for SARS-CoV-2 at 11 sites from July 1 to July 29, 2020, and were contacted by phone to complete a survey 14 days to 23 days after the date they received SARS-CoV-2 testing. Among the 802 adults contacted, 314 individuals were included in the final analyses; 154 who tested positive and 160 who tested negative for COVID-19. All participants were symptomatic at the time of their test. Participants were asked about close contact (within 6 feet for at least 15 minutes) with a person with known COVID-19, workplace exposures, mask-wearing behavior, and community activities within 14 days of symptom onset. Close contact with a person with known COVID-19 was more commonly reported among case patients (42%) than among control participants (14%). No significant differences were observed in the bivariate analysis between case patients and control participants in shopping, gatherings with 10 or fewer persons in a home, going to an office setting, going to a salon, gatherings with more than 10 persons in a home, going to a gym, using public transportation, going to a bar/coffee shop, or attending a church/religious gathering. Case patients were more likely to have reported dining at a restaurant (adjusted odds ratio [aOR] = 2.4; 95% CI 1.5 - 3.8) in the 2 weeks before illness onset than control participants. When the analysis was restricted to the 225 participants who did not report recent close contact with a person with known COVID-19, case patients were more likely than control participants to have dined at a restaurant (aOR = 2.8; 1.9 - 4.3) or to have visited a bar/coffee shop (aOR = 3.9; 1.5 - 10.1). One limitation the authors report is the inability to evaluate bar and coffee shop exposure separately, which may represent different risks. Fisher KA, Tenforde MW, Feldstein LR, et al. Community and close contact exposures associated with COVID-19 among symptomatic adults ≥18 years in 11 outpatient health care facilities — United States, July 2020. MMWR Morb Mortal Wkly Rep 2020;69(36):1258–1264.

John Hickner, MD, MS
Professor Emeritus
Dept of Family Medicine
Michigan State University
East Lansing, MI

Copyright © 2020 John Wiley & Sons, Inc.