Patterns of COVID-19 in Health Professionals Offers Clues for Disease Control

Roughly one out of every 100 healthcare workers (HCWs) employed at hospitals treating COVID-19 patients tests positive for SARS-CoV-2, the virus responsible for the disease, according to two new studies published this week in JAMA Network Open. 

In an analysis of a large, tertiary care hospital in Wuhan, China, the epicenter of the COVID-19 worldwide pandemic, 110 of 9,684 HCWs (1.1%) tested positive for the disease. Of those, 17 worked in fever clinics or wards treating patients with COVID-19. This translates into an infection rate of 0.5% among first-line workers.

Paradoxically, the infection rate was higher among those not on the front line, with 1.4% of 6,574 of these HCWs infected with SARS-CoV-2. In fact, the risk of infection was more than 16 times greater among non-first-line nurses younger than 45 compared with first-line physicians 45 years and older. Xiaoquan Lai, MD (Tongji Medical College, Wuhan, China), and colleagues say the higher infection rate among these workers is likely explained by the long incubation time of COVID-19, which made it hard to recognize patients with the disease in its early stage.

“Insufficient protective measures were available in clinical departments other than fever clinics and wards, which could have put non-first-line HCWs at a higher risk,” write Lai and colleagues. “Our results indicated that most HCWs (60.0%) were infected during the early stage of the COVID-19 outbreak.” Additionally, the virulence of SARS-CoV-2 might not be as severe as SARS, meaning infected patients might have had subtle, atypical, or even no symptoms. “The existence of such patients could greatly endanger the health of staff even though clinical areas caring for patients with and without COVID-19 were separated from each other.”

Of the HCWs with COVID-19, nearly 85% had nonsevere disease, although one person died. Fever was the most common symptom, but it was present in just 60.9% of HCWs. The other most common symptoms included myalgia or fatigue (60.0%), cough (56.4%), sore throat (50.0%), and muscle aches (45.5%).

Community-Acquired SARS-CoV-2

In the Netherlands, investigators also took a look at the risk of infection to HCWs, although their goal differed from the Chinese study. In this analysis, lead researcher Marjolein Kluytmans-van den Bergh, PhD (Amphia Hospital, Breda, the Netherlands), and colleagues characterized the prevalence and clinical presentation of HCWs with symptoms of COVID-19 at two Dutch hospitals during the early phase of pandemic.

Senior investigator Jan Kluytmans, PhD (Amphia Hospital), told TCTMD that the first patient with COVID-19 in the Netherlands was reported on February 27, 2020. In the following two weeks, another 127 COVID-19 cases were documented; this included nine HCWs who worked at the Dutch hospitals, only one of whom had traveled to China or northern Italy. “We were especially interested in our healthcare workers, such as what kind of symptoms they had and how many were infected,” he said. “We wanted to learn more so we started testing our healthcare workers with even the slightest complaints for COVID-19.”

In total, 9,705 HCWs were employed at the Amphia Hospital and Elisabeth-TweeSteden Hospital, both in the south of the country. Of these, 1,353 reported a fever or respiratory symptoms between March 7 and March 12, 2020, and were tested for COVID-19. Of these, 86 HCWs, or 6%, had a positive diagnosis. This represents 1% of all the HCWs at the two hospitals. A little more than half of HCWs reported fever as a symptom, while 12% reported feeling feverish without having their temperature checked. Eighty of the 86 HCWs met a case definition of fever and/or coughing and/or shortness of breath.

This identification of HCWs with COVID-19 changed national policy, said Kluytmans. Initially, as recommended by the World Health Organization and Dutch national health authorities, fever was necessary to meet the definition of a COVID-19 case requiring testing, but now any patient presenting to the hospital with respiratory symptoms, even mild ones, is tested for COVID-19.

“We found that only half had fever and that much milder symptoms could be associated with COVID-19,” Kluytmans continued. “That is now the main issue with this disease and controlling it. It often presents, especially in younger patients, with very mild symptoms, or they might experience specific symptoms. That’s the big struggle we have with fighting this disease. It’s difficult to identify the cases.”   

The HCWs worked in 52 different hospital departments, including 36 medical wards, and most experienced mild disease. Nearly 25% had no contact with patients during their daily work and only 3% reported exposure to a patient diagnosed with COVID-19 before their symptoms started. “For healthcare workers, the majority of [COVID-19] is picked up in the community,” said Kluytmans.

HCWs Remaining Vigilant

In an editorial, Vincent Chi-Chung Cheung, MD, Shuk-Ching Wong, MNurs (both from Queen Mary Hospital, Hong Kong), and Kwok-Yung Yuen, MD (University of Hong Kong), state that the higher rate of infection among HCWs working in lower-risk areas of the hospital in Wuhan, China, needs to be studied further. These workers might not be aware of the risks, although that is unlikely given that infection control training has been given to all HCWs.

“The presence of patients with subclinical or asymptomatic SARS-CoV-2 infection may have played an important role in nosocomial transmission in low-risk areas, especially when aerosol-generating procedures, such as cardiopulmonary resuscitation, manual ventilation, endotracheal intubation, tracheostomy, noninvasive ventilation, and bronchoscopy, are performed,” they write.

The editorialists also state that, like others in the community, HCWs need to be vigilant about community risk, noting that it is important for persons to maintain social distance and avoid social gatherings after work. To TCTMD, Kluytmans noted that Carnival takes place in Holland every February, and this 3-day festival is believed to have contributed to the transmission of SARS-CoV-2.