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What are the sources of exposure in healthcare personnel with coronavirus disease 2019 infection?

Published:August 11, 2020DOI:https://doi.org/10.1016/j.ajic.2020.08.004

      Highlights

      • Healthcare personnel are at risk for nosocomial acquisition of COVID-19.
      • We evaluated the exposure history of hospital personnel with COVID-19.
      • Twenty-five percent of personnel with COVID-19 were exposed to an infected patient or co-worker.
      • Exposure to infected co-workers occurred in nonpatient care settings.
      • Fourteen percent of personnel with COVID-19 were exposed in the community.
      In our facility, 25% of personnel with coronavirus disease 2019 (COVID-19) had a higher-risk exposure to an infected patient or co-worker and 14% reported a higher-risk exposure in the community. All higher-risk exposures to infected patients occurred on non-COVID-19 units, often when there was a delay in diagnosis because COVID-19 was not initially suspected. Higher-risk exposures to co-workers with COVID-19 often involved lapses in compliance with masking in nonpatient care areas such as nursing stations and staff work or break rooms.

      Key Words

      Introduction

      One of primary goals of infection control programs during the coronavirus disease 2019 (COVID-19) pandemic is to minimize the risk for acquisition of infection by healthcare personnel. Factors such as inadequate personal protective equipment, work overload, insufficient diagnostic testing and exposure to infected patients have been associated with risk for infection in healthcare personnel.
      Characteristics of health care personnel with COVID-19 – United States, February 12 – April 9, 2020

      Shrestha NK, Marco Canosa F, Nowacki AS, et al. Distribution of transmission potential during non-severe COVID-19 illness [e-pub ahead of print]. Clin Infect Dis. https://doi.org/10.1093/cid/ciaa886. Accessed August 28, 2020.

      Roxby AC, Greninger AL, Hatfield KM, et al. Outbreak investigation of COVID-19 among residents and staff of an independent and assisted living community for older adults in Seattle, Washington. JAMA Intern Med. 2020;180:1101-1105.

      Mani NS, Budak JZ, Lan KF, Bryson-Cahn C, Allison Zelikoff, Gwendolyn E C Barker, et al. Prevalence of COVID-19 infection and outcomes among asymptomatic healthcare workers in Seattle, Washington. Clin Infect Dis. 2020;71:2702-2707.

      Ran L, Chen X, Wang Y, Wu W, Zhang L, Tan X. Risk factors of healthcare workers with corona virus disease 2019: a retrospective cohort study in a designated hospital of Wuhan in China. Clin Infect Dis. 2020;71:2218-2221

      In addition to infected patients, healthcare personnel are at risk for nosocomial acquisition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from co-workers with COVID-19 infection. In a recent study from Greece approximately half of all high-risk exposures were to healthcare personnel with COVID-19.

      Maltezou HC, Dedoukou X, Tseroni M, et al. SARS-CoV-2 Infection in healthcare personnel with high-risk occupational exposure: evaluation of seven-day exclusion from work policy. Clin Infect Dis. 2020;71:3182-3187

      There is an urgent need for additional information regarding sources of work-related exposure to SARS-CoV-2. Therefore, we evaluated the exposure history of healthcare personnel with COVID-19 in an acute care hospital during a 4-month period.

      Methods

      Study setting

      The Cleveland VA Medical Center is a 215-bed hospital with a dedicated 22-bed COVID-19 ward; eight beds in the medical intensive care unit are also dedicated to care of COVID-19 patients. The first COVID-19 patient was identified in the facility on March 15, 2020. The average daily census of COVID-19 inpatients peaked in May at 18 cases, decreasing to 4 and 7 cases on average in June and July, respectively. For personnel with symptoms concerning for COVID-19 infection, testing was available if requested at the Cleveland VA Medical Center or was obtained through their primary care providers. For asymptomatic healthcare personnel, no testing was offered unless they were identified as being at risk through contact tracing.
      Personnel caring for known or suspected COVID-19 patients or performing aerosol-generating procedures wore either a powered air purifying respirator or an N95 respirator with a face shield. On April 27, 2020, universal masking of personnel was implemented throughout the facility and patients were required to wear cloth facemasks when out of their room or when personnel entered the room. Diagnostic testing was initially restricted to symptomatic patients and personnel, but on May 17, 2020 was expanded to include all admissions and prior to many medical procedures. Personnel were screened for COVID-19 symptoms on arrival to work and encouraged not to work and/or to request testing if they had symptoms consistent with SARS-CoV-2 infection.

      Study design

      The study protocol was approved by the Cleveland VA Medical Center's Institutional Review Board. Between March 15, 2020 and July 15, 2020, we examined the exposure history of personnel with COVID-19 infection or asymptomatic carriage. A diagnosis of COVID-19 infection required symptoms consistent with COVID-19 and a nasopharyngeal swab polymerase chain reaction assay positive for SARS-CoV-2. Asymptomatic carriage was diagnosed if there was a positive nasopharyngeal swab test in the absence of symptoms consistent with COVID-19.
      All personnel diagnosed with COVID-19 infection or asymptomatic carriage were interviewed by personnel health department employees using a standardized checklist to identify potential exposures. Higher-risk exposures were defined as prolonged (greater than 15 minutes), close (less than 6 feet) contact occurring within 2 days before symptom onset through the time when the source individual met criteria for discontinuation of transmission-based precautions.

      Interim U.S. guidance for risk assessment and work restrictions for healthcare personnel with potential exposure to COVID-19. Available at: https://www.cdc.gov/coronavirus/2019-ncov/hcp/guidance-risk-assesment-hcp.html. Accessed August 28, 2020.

      For exposures to personnel, we classified contacts that did not meet criteria for higher-risk exposure as lower-risk exposures. Exposures were categorized as contacts with patients, personnel, family members, or individuals in the community with COVID-19. Personnel were classified as nurses, physicians, ancillary staff providing patient care and administrative personnel. Personnel providing patient care were stratified based on whether they worked on the COVID-19 wards or in other areas.

      Results

      During the 4-month study period, 1,534 personnel had nasopharyngeal swabs collected for SARS-CoV-2 testing, including 1,111 (72.4%) tested due to presence of symptoms and 423 (27.6%) asymptomatic individuals tested as part of contact tracing. Of the 1,534 personnel tested, 96 (6.3%) had nasopharyngeal swabs with positive PCR results, including 90 (93.4%) with and 6 (6.3%) without COVID-19 symptoms. Of the 96 cases, 24 (25.0%) had a higher-risk exposure at work, including 18 exposures to COVID-19 patients and 6 exposures to infected personnel. Ten additional personnel with COVID-19 had a lower-risk exposure to staff members with COVID-19. Higher-risk exposures to family members or to infected individuals in the community were reported by 7 (7.3%) and 6 (6.3%) of the 96 personnel with COVID-19.
      Of the 96 personnel with positive PCR results for SARS-CoV-2, 53 (55.2%) were nursing staff, 3 (3.1%) were physicians, 16 (16.7%) were ancillary clinical staff, and 24 (25.0%) were nonclinical personnel. No cases occurred in personnel working on COVID-19 wards. None of those with a positive result had previously been tested for COVID-19 in our healthcare system.
      Figure 1 shows the number of higher-risk exposures to known COVID-19 cases over the course of the study by exposure category. Exposures to infected patients were common early in the outbreak and often occurred when recognition of COVID-19 was delayed due to absence of fever and atypical presentations (eg, diabetic ketoacidosis and confusion or shortness of breath with no other respiratory symptoms). All higher-risk exposures to COVID-19 patients occurred on non-COVID-19 wards.
      Fig 1
      Fig 1Number of high-risk exposures to known COVID-19 cases over the course of the study by exposure category.
      Table 1 provides a summary of the 6 higher-risk and 10 lower-risk exposures of personnel infected with COVID-19 to other staff members with COVID-19. Exposures to personnel with COVID-19 often occurred when infected personnel were pre-symptomatic (4 of 6 higher-risk exposures) or when they worked despite having symptoms consistent with COVID-19 (eg, sore throat or nasal congestion initially attributed to allergies followed by diagnosis of COVID-19 when symptoms progressed). However, 2 of the infected personnel admitted to working despite having prominent symptoms including cough. Seven of the 10 (70%) lower-risk exposures occurred when the infected personnel were pre-symptomatic or asymptomatic. All higher-risk and lower-risk exposures to personnel with COVID-19 occurred on non-COVID-19 wards.
      Table 1Summary of 16 exposures to personnel infected with COVID-19 for personnel subsequently diagnosed with COVID-19
      Occupation of COVID-19 caseOccupation of COVID-19 exposure sourceDate of source case diagnosis with COVID-19Symptomatic at time of exposure? Yes/No (symptoms)Type of exposure
      Definite higher-risk exposure to personnel with COVID-19
      Higher-risk exposures were defined as prolonged (greater than 15 minutes), close (less than 6 feet) contact occurring within 2 days before symptom onset through the time when the source individual met criteria for discontinuation of transmission-based precautions based on Centers for Disease Control and Prevention criteria.6
      Registered nurseRegistered nurse4/2/20Yes (diarrhea, sore throat)Worked together in office including unmasked contact
      Registered nurseRegistered nurse5/20/20NoAte lunch together with no masking or social distancing
      Registered nurseRegistered nurse5/11/20NoAte lunch together with no masking or social distancing
      Instrument TechnicianRegistered nurse5/12/20NoAte lunch together with no masking or social distancing
      Student nurseStudent Nurse6/22/20Yes (cough)Frequent prolonged unmasked contact during social interactions at work
      Ward clerkNursing assistant6/22/20NoProlonged contact at nursing station, unreliable use of masks in shared work areas
      Shared work areas included the nursing station and personnel work and break rooms.
      Lower-risk exposure to personnel with COVID-19
      PhysicianPhysician3/29/20Yes (cough, nasal congestion)Worked on same unit, interactions with masking by case but not by source with COVID-19
      Nursing assistantRegistered nurse6/29/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      Registered nurseStudent nurse6/20/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      Nursing assistantStudent nurse6/20/20Yes (cough)Unclear contact but worked on same ward with unreliable use of masks in shared work areas
      Registered nurseStudent nurse6/24/20Yes (cough)Unclear contact but worked on same ward with unreliable use of masks in shared work areas
      Registered nurseRegistered nurse6/25/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      Registered nurseNursing assistant6/25/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      Registered nurseNursing assistant6/26/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      Registered nurseNursing assistant6/25/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      Nursing assistantStudent Nurse6/25/20NoUnclear contact but worked on same ward with unreliable use of masks in shared work areas
      COVID-19, coronavirus disease 2019.
      low asterisk Higher-risk exposures were defined as prolonged (greater than 15 minutes), close (less than 6 feet) contact occurring within 2 days before symptom onset through the time when the source individual met criteria for discontinuation of transmission-based precautions based on Centers for Disease Control and Prevention criteria.

      Maltezou HC, Dedoukou X, Tseroni M, et al. SARS-CoV-2 Infection in healthcare personnel with high-risk occupational exposure: evaluation of seven-day exclusion from work policy. Clin Infect Dis. 2020;71:3182-3187

      Shared work areas included the nursing station and personnel work and break rooms.
      Five of 6 (83.3%) higher-risk exposures to personnel occurred after universal masking of personnel and patients was implemented. These higher-risk exposures often involved noncompliance with facemask use in nonclinical shared work areas (eg, nursing station, staff work, or break rooms) or during activities such as meals when facemasks were removed, and social distancing was not maintained.

      Discussion

      We found that 25% of healthcare personnel testing positive for SARS-CoV-2 had a higher-risk exposure at work (more than 15 minutes of exposure within 6 feet of a symptomatic or pre-symptomatic individual), including 18 exposures to COVID-19 patients and 6 to infected personnel. An additional 14% of infected personnel reported higher-risk exposures to family members or other infected individuals in the community. These findings have important implications for efforts to minimize the risk for acquisition of SARS-CoV-2 by healthcare personnel.
      For personnel acquiring COVID-19, higher-risk exposures to infected patients were relatively common early in the outbreak. These exposures all occurred on non-COVID-19 units, often when there was a delay in diagnosis of infected patients because COVID-19 was not initially suspected. Such exposures were markedly reduced as availability of testing increased and clinicians had increased awareness of atypical presentations. Implementation of routine admission screening for SARS-CoV-2 also reduced the likelihood that cases would be missed on admission. Only 3 of the 18 (16.7%) exposures associated with acquisition of COVID-19 by personnel occurred after routine admission screening was implemented.
      The finding that infected personnel are an important source of exposure to COVID-19 by personnel is consistent with the recent report of Maltezou et al.

      Maltezou HC, Dedoukou X, Tseroni M, et al. SARS-CoV-2 Infection in healthcare personnel with high-risk occupational exposure: evaluation of seven-day exclusion from work policy. Clin Infect Dis. 2020;71:3182-3187

      In our facility, higher-risk exposures to personnel with COVID-19 often occurred when the source individual was presymptomatic or had symptoms that were initially attributed to noninfectious conditions such as allergies. All higher-risk exposures occurred in nonpatient care settings such as nursing stations and staff work or break rooms. The exposures were due to noncompliance with masking in these settings or occurred during meals when facemasks had to be removed but social distancing was not maintained. There were also numerous instances of exposures to infected personnel that did not qualify as higher-risk exposures, but that could potentially have resulted in transmission. Many personnel working on the same ward as a source individual had frequent short-duration contacts within 6 feet or shared fomites that might potentially result in transmission.
      • Otter JA
      • Donskey C
      • Yezli S
      • Douthwaite S
      • Goldenberg SD
      • Weber DJ
      Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: possible role of dry surface contamination.
      ,
      • Boone SA
      • Gerba CP
      Significance of fomites in the spread of respiratory and enteric viral disease.
      One notable finding in our study was that no personnel working on the COVID-19 ward or intensive care unit developed COVID-19. The fact that all patients on the wards had known or suspected COVID-19 minimized the risk of unprotected exposure to a patient with unsuspected infection. Observations suggested that compliance with universal masking was excellent on these wards including in nonpatient care areas. Protocols were also in place to ensure frequent cleaning and disinfection, including the nursing stations and staff work or break rooms.
      Our study has some limitations. Only one facility was included in a setting with adequate supplies of personal protective equipment and access to diagnostic testing. Additional studies are needed in other settings. Our assessment of exposures and symptoms relied on interviews with personnel. It is possible that some of the information provided was inaccurate particularly if personnel did not acknowledge exposures or working while ill. We did not perform molecular typing to determine the relatedness of source and case SARS-CoV-2 genetic material. Recent studies have demonstrated the value of sequencing analysis in determining the source of acquisition of SARS-CoV-2.

      Safdar N, Moreno GK, Braun KM, Friedrich TC, O'Connor DH. Determining the source of transmission of SARS-CoV-2 infection in a healthcare worker [e-pub ahead of print]. medRxiv. https://doi.org/10.1101/2020.04.27.20077016. Accessed August 28, 2020.

      Finally, it is notable that 49 of the 96 (51%) personnel with positive tests for SARS-CoV-2 did not have known higher or lower-risk exposures at work or higher-risk exposures in the community. Although a standardized interview was conducted, we cannot exclude the possibility that more intensive and/or anonymous interviews might identify additional exposures.

      Conclusion

      In our facility, 25% of personnel with COVID-19 had a higher-risk exposure to an infected patient or co-worker at work and 14% reported a higher-risk exposure in the community. Improved detection of patients with atypical presentations and efforts to reduce high-risk contacts among personnel may reduce the risk for acquisition of SARS-CoV-2. For personnel, efforts are needed to reduce lapses in compliance with masking in nonpatient care areas. Because most personnel with COVID-19 did not report a higher-risk exposure, there is a need for studies to identify sources of acquisition in the absence of such exposures.

      Acknowledgments

      We thank the nurses, environmental management services personnel, and patients at the Cleveland VA Medical Center who participated in the study.

      References

        • Characteristics of health care personnel with COVID-19 – United States, February 12 – April 9, 2020
        MMWR Morb Mortal Wkly Rep. 2020; 69: 477-481
      1. Shrestha NK, Marco Canosa F, Nowacki AS, et al. Distribution of transmission potential during non-severe COVID-19 illness [e-pub ahead of print]. Clin Infect Dis. https://doi.org/10.1093/cid/ciaa886. Accessed August 28, 2020.

      2. Roxby AC, Greninger AL, Hatfield KM, et al. Outbreak investigation of COVID-19 among residents and staff of an independent and assisted living community for older adults in Seattle, Washington. JAMA Intern Med. 2020;180:1101-1105.

      3. Mani NS, Budak JZ, Lan KF, Bryson-Cahn C, Allison Zelikoff, Gwendolyn E C Barker, et al. Prevalence of COVID-19 infection and outcomes among asymptomatic healthcare workers in Seattle, Washington. Clin Infect Dis. 2020;71:2702-2707.

      4. Ran L, Chen X, Wang Y, Wu W, Zhang L, Tan X. Risk factors of healthcare workers with corona virus disease 2019: a retrospective cohort study in a designated hospital of Wuhan in China. Clin Infect Dis. 2020;71:2218-2221

      5. Maltezou HC, Dedoukou X, Tseroni M, et al. SARS-CoV-2 Infection in healthcare personnel with high-risk occupational exposure: evaluation of seven-day exclusion from work policy. Clin Infect Dis. 2020;71:3182-3187

      6. Interim U.S. guidance for risk assessment and work restrictions for healthcare personnel with potential exposure to COVID-19. Available at: https://www.cdc.gov/coronavirus/2019-ncov/hcp/guidance-risk-assesment-hcp.html. Accessed August 28, 2020.

        • Otter JA
        • Donskey C
        • Yezli S
        • Douthwaite S
        • Goldenberg SD
        • Weber DJ
        Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: possible role of dry surface contamination.
        J Hosp Infect. 2016; 92: 235-250
        • Boone SA
        • Gerba CP
        Significance of fomites in the spread of respiratory and enteric viral disease.
        Appl Environ Microbiol. 2007; 73: 1687-1696
      7. Safdar N, Moreno GK, Braun KM, Friedrich TC, O'Connor DH. Determining the source of transmission of SARS-CoV-2 infection in a healthcare worker [e-pub ahead of print]. medRxiv. https://doi.org/10.1101/2020.04.27.20077016. Accessed August 28, 2020.