According to a JAMA Network Open study, the greatest COVID-19 risk factors for healthcare personnel (HCP) aren’t patient contact or clinical duties but rather community exposure.
The study looked into survey and serologic data from ~25,000 HCPs in the US: Atlanta, Georgia (Emory Healthcare), Baltimore, Maryland (Johns Hopkins Medicine and University of Maryland Medical System), and Chicago, Illinois (Rush University System).
Researchers found that exposure to a positive community contact increased the likelihood of infection 3.5 times and high cumulative exposure increased the likelihood 1.8 times.
Researchers collected volunteer samples and survey data from 24,749 HCP across four large healthcare systems and three states (Georgia, Maryland, and northeast Illinois).
Serologic tests looking for COVID-19 antibodies showed that, from Apr 19 to Aug 30, 2020, 4.4% of HCPs were positive, ranging from 3.1% (University of Maryland) to 5.7% (University of Emory). Of the HCP, 69.6% were younger than 50, 78.2% were women, and 61.2% were White. About half (50.2%) of all participants had contact with COVID-19 patients in any way, and 35.9% worked in inpatient settings.
The most common occupations were nurses (31.6%), nonclinical staff (21.4%), and physicians (18.2%); 9.7% worked in the emergency department.
Even though HCP were likely to have work-related contact with people infected by COVID-19, the adjusted odds ratio (aOR) did not show significantly increased risk (1.1; 95% confidence interval [CI], 0.9 to 1.3). Working as a nurse also did not increase odds (aOR, 1.1; 95% CI, 0.9 to 1.3), nor did working in the emergency department (aOR, 1.0; 95% CI, 0.8 to 1.3).
While environmental services such as physical, occupational, or speech therapy did show an increased likelihood of infection (aOR, 1.5; 95% CI, 0.8 to 3.1), the researchers say those data may be skewed because of the small sample size (122, 0.5%).
“The news is reassuring in that it shows the measures taken are working to prevent infections from spreading in healthcare facilities,” said study co-investigator Dr. Anthony Harris, MD, MPH, in a University of Maryland press release.
Community factors, on the other hand, carried the highest risk of COVID-19 infection. Being in contact with someone from the community (for example a friend or housemate) increased the likelihood by 3.5 (95% CI, 2.9 to 4.1). Only 7.0% (1,730) of participants had a known COVID-19 exposure from the community, but of those, 12.6% had confirmed COVID-19 infection, compared with 3.5% of the 20,072 who said they didn’t have any COVID-19 community contacts.
The cumulative incidence in the community also affected infection likelihood, with an aOR of 1.8 (95% CI, 1.3 to 2.6). Data collected the week prior to participants’ COVID-19 tests showed that the average prevalence was 72.4 infections per 10,000 people, but it could range anywhere from 8.2 to 275.6.
Additionally, age affected the risk of infection. HCPs who were younger than 30 were more likely to be seropositive compared with those 60 and older (aOR, 1.3; 95% CI, 1.0 to 1.7), and as age increased, odds decreased. This could be because this age-group may convene more with friends, go out in the community more often, or have children who attend school or daycare.
The study was not able to assess COVID-19 mitigations across the different sites, but the researchers say it nonetheless affirms that the control measures that healthcare systems use, such as disinfecting and personal protective equipment (PPE), are effective.
Dr. Melvin Sanicas (@Vaccinologist) is a physician-scientist specializing in vaccines, infectious diseases, and global health.