Editor’s note: Find the latest COVID-19 news and guidance in Medscape’s Coronavirus Resource Center.
Soon after the first case of COVID-19 was identified in the Netherlands, a substantial number of healthcare workers (HCWs) at two hospitals there — about 1% — tested positive for the novel coronavirus, according to a study published online May 21 in JAMA Network Open.
“This unexpected high prevalence supported the hypothesis of hidden community spread of SARS-CoV-2,” the researchers write.
Exposure to patients also may be a key factor, said Aaron E. Glatt, MD, a spokesperson for the Infectious Diseases Society of America and professor and chair of medicine at Mount Sinai South Nassau in Oceanside, New York.
In the early stages of a COVID-19 outbreak, healthcare workers may not recognize that patients have the disease. Consequently, they are at increased risk when they enter patients’ rooms without personal protective equipment (PPE), said Glatt, who was not involved with the Dutch study.
Once PPE is properly used, however, it is quite effective, Glatt said. Unpublished data from New York suggest that, with proper precautions, rates of infection in healthcare workers are lower than in the general community, he said.
That view is supported by data from a second study, also published in JAMA Network Open by Xiaoquan Lai, MD, from Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China, and colleagues.
Lai and colleagues found that most HCW infections occurred early in the disease outbreak, before clinicians may have been fully aware of the risk — and thus may not have been using adequate PPE.
“At a minimum, every healthcare worker should be given appropriate PPE and taught to use it properly,” he said. In addition, healthcare workers should have a “very, very high suspicion” for COVID-19. Infected people often are asymptomatic, which necessitates wearing masks and practicing social distancing at all times, Glatt noted.
Fever Common but Not Ubiquitous
Following detection of the first case of COVID-19 in the Netherlands on February 27, nine HCWs at the two teaching hospitals were diagnosed with COVID-19. To better understand the overall case number, Marjolein F. Q. Kluytmans-van den Bergh, PhD, from the department of infection control, Amphia Hospital, Breda, the Netherlands, and colleagues performed a cross-sectional study among HCWs with fever or respiratory symptoms.
Through March 12 at the two hospitals, HCWs with fever or respiratory symptoms were asked to voluntarily participate in screening. Investigators tested for SARS-CoV-2 using semiquantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) on oropharyngeal samples and documented symptoms using structured interviews.
Of 9705 HCWs employed at the hospitals, 1353 (14%) reported fever or respiratory symptoms and underwent testing. Of those, 86 (6%) were infected with SARS-CoV-2. Patients with the virus had a median age of 49 years.
Most infected HCWs had mild disease. Just over half (53%) of those who tested positive had fever. Two HCWs with COVID-19 required inpatient care but did not have critical disease at the time of the report.
Among those who tested positive, three had traveled to China or northern Italy, and three had been exposed to an inpatient with a diagnosis of COVID-19 before the onset of their symptoms.
Notably, seven of those who tested positive reported being symptomatic prior to the country’s first reported COVID-19 diagnosis. About 24% of the infected healthcare workers had no patient contact during their work, and 63% had worked while symptomatic.
“During the containment phase and within 2 weeks after the first Dutch case was detected, a substantial proportion of HCWs with self-reported fever or respiratory symptoms were infected with SARS-CoV-2, likely as the result of acquisition of the virus in the community during the early phase of local spread,” Kluytmans-van den Bergh and colleagues concluded. “This observation confirms the insidious nature of SARS-CoV-2 spread, given the high prevalence of mild clinical presentations that may go undetected.”
In addition, the data indicate that the case definition for suspected COVID-19 should include fever as a possible but not required symptom, the researchers say. Adding severe myalgia and general malaise to the definition can further improve the sensitivity of COVID-19 detection, they say.
“Overall, healthcare workers in the Netherlands who were found to be infected were employed in 52 different hospital departments,” write Vincent Chi-Chung Cheng, MD, from Queen Mary Hospital, Hong Kong, and colleagues in an accompanying editorial. “The diversity of working locations among them suggests that hospital outbreak was unlikely… This does highlight how important it is for HCWs, like any other person, to remain vigilant of community risk by maintaining social distancing and avoiding social gatherings after work hours.”
Relative to patients from the general public, HCWs “appear to experience less severe illness and mortality…possibly related to younger age and fewer comorbid conditions,” according to a recent review in the Annals of Internal Medicine that examined studies of coronavirus in this population. The review incorporated data from a preprint of the Dutch study, as well as reports from China and prior coronavirus outbreaks.
“The evidence on SARS-CoV-2 infections in HCWs is sparse and has methodological limitations,” Roger Chou, MD, of Oregon Health & Science University in Portland, and colleagues write. More research is needed to understand how infection affects this group, including their ability to work and the potential for transmission to family members and close contacts. Studies that identify optimal methods for reducing their risk are urgently needed, Chou and colleagues say.
One coauthor of the study served as a scientific advisory board consultant for Luminex. Cheng and colleagues have disclosed no relevant financial relationships.