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Community and Close Contact Exposures Associated with COVID-19 Among Symptomatic Adults 18 Years and older in 11 Outpatient Health Care Facilities — United States, July 2020

Our take —

This case-control study aimed to assess community and close contact exposures associated with COVID-19. This study included 154 cases and 160 controls who presented with symptoms to healthcare facilities within a US network who were tested for SARS-COV-2. COVID-19 cases were 2.4 times more likely to have reported dining at a restaurant in the 2 weeks preceding illness onset than controls. No differences between cases and controls were observed among several other community exposures. These findings should be interpreted in the context of several limitations, especially that controls were not positive for SAR-CoV-2, but they may have been infected with a pathogen with similar transmission characteristics. Although reported mask use in public spaces was high amongst both cases and controls, cases were nearly 3 times more likely to have a known COVID-19 contact many of which would have been contacts in private spaces without masks and cases were significantly higher amongst those attending restaurants where masks were not used by participants. This study suggests that restaurants may be a greater exposure risk than other community activities that do not involve eating or drinking where mask use is uncommon.

Study design

Case-Control

Study population and setting

This case-control study aimed to assess community and close contact exposures associated with COVID-19. This study included adults who were symptomatic and tested for COVID-19 the first time at one of 11 Influenza Vaccine Effectiveness in the Critically Ill (IVY) Network sites across the U.S. between the period of July 1 to 29, 2020. The study included 154 cases and 160 controls. Cases were defined as individuals with evidence of SARS-CoV-2 RNA by RT-PCR in one the networks sites and were selected by random sampling of confirmed patients within a specific time period. Controls were symptomatic individuals from the network sites who tested negative for SARS-CoV-2. Multiple controls were randomly selected for each case, matching on age, sex, and study site. Information on demographic characteristics, medical history, exposure history, community activities, and mask wearing was collected through structured retrospective interviews with participants.

Summary of Main Findings

Close contact with one or more persons with known COVID-19 was reported by 42% of cases and 14% of controls. Cases were more likely to have reported dining at a restaurant in the 2 weeks preceding illness onset than were controls (adjusted odds ratio [aOR] 2.4; 95% CI 1.5–3.8), even after restricting the analysis to participants without a known close contact to be confirmed with SARS-Cov-2 (aOR 2.8, 95% CI 1.9–4.3). Restricted analysis also suggests that cases were more likely than control to have reported going to a bar/coffee shop (aOR 3.9, 95% CI 1.5–10.1) in the 2 weeks preceding illness onset. No differences between cases and controls were observed among those who reported shopping; gatherings with ≤10 persons in a home; going to an office setting; going to a salon; gatherings with >10 persons in a home; going to a gym; using public transportation; or attending church/religious gatherings.

Study Strengths

This study attempts to differentiate between different community activity exposure risks.

Limitations

These findings should be interpreted in the context of several limitations. Authors attempted to match cases and controls at a ratio of 1:2; however, due to ineligibility or refusal to participate the matching ratio was not possible, and matching based on age and sex was not maintained. Those who agreed to participate may differ from those who did not. Participation as well as recall of exposures may have been influenced by symptom severity, and therefore the results may be subject to bias. Controls included individuals who presented at the health facility and reported symptoms, however, did not test positive for COVID-19. These patients may have illness due to another pathogen with similar exposure risks and modes of transmission. Therefore, it may be difficult to differentiate between exposure risks between cases and controls. Finally, a significant limitation was that data were not able to distinguish between indoor and outdoor dining and indoor/outdoor bar/coffee shop attendance.

Value added

This study suggests that the restaurant environment may a particular concern for risk of exposure to SARS-CoV-2 compared to other community activities that do not involve removing masks alongside being in shared indoor spaces.

This review was posted on: 16 October 2020