CDC examines COVID-19 outbreak among U.S. office workers: a case study in transmission

By Angela Betsaida B. Laguipo, BSNFeb 1 2021

The U.S. currently reports the highest number of coronavirus disease 2019 (COVID-19) cases worldwide. To date, over 25.59 million people have been infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the causative pathogen of COVID-19 – which has resulted in 429,000 deaths.

Researchers from the Centers for Disease Control and Prevention and the Federal Emergency Management Agency in the U.S. found that despite mitigation efforts, two COVID-19 outbreaks emerged among office workers in Washington, DC.

Study: SARS-CoV-2 Infection and Mitigation Efforts among Office Workers, Washington, DC, USA. Image Credit: Halfpoint / Shutterstock

COVID-19 outbreaks

In response to the coronavirus pandemic, the Federal Emergency Management Agency (FEMA) rolled out the National Response Coordination Center in Washington, DC, on March 19, 2020.

From March onwards, the U.S. has seen skyrocketing cases of SARS-CoV-2 infection. In Washington, DC., about 200 cases had been reported since March 7. The government imposed lockdown orders and closed nonessential businesses by March 24.

During this time, FEMA remained open, and to protect the staff from COVID-19, all employees were screened for their symptoms and temperature readings. However, by April 6, six cases were identified.

The agency implemented infection control measures, including requiring face masks at all times, social distancing of about 6 feet between employees, and reducing occupancy in the open office space building from 1,300 persons to just 400 persons.

Conducting a serologic survey

In the report, which appeared in the journal Emerging Infectious Diseases, the researchers explored workplace and community factors tied to COVID-19.

To do this, they conducted a serologic survey of SARS-CoV-2 antibodies among the employees after the infection control measures and mitigation efforts were imposed. Apart from the serologic survey, the team also examined occupational case surveillance data.

The researchers identified the staff who worked in the building between April 1 and 22 through turnstile records. The team sent emails to these employees to invite them to take the survey. From April 23 to 29, the survey participants completed a self-administered questionnaire online to assess their potential community and workplace exposure to SARS-CoV-2. Blood samples were obtained and tested for SARS-CoV-2 using an enzyme-linked immunosorbent assay (ELISA) test.

Survey findings

The survey findings showed that of the 466 participants, 15 tested positive for antibodies against SARS-CoV-2. Of these, 11 individuals reported never having been tested for SARS-CoV-2 infection, and eight said they did not develop symptoms suggestive of COVID-19.

The participants spent an average of 20.5 days in the FEMA building since March 2020. The mitigation measures did not have any differences in participants who tested positive and those who were negative. However, a higher percentage of the participants who shared a workspace were seropositive.

Further, 13.3 percent of the people who spent more than ten minutes less than six feet from a COVID-19 case in the FEMA building were seropositive, which means they have antibodies against SARS-CoV-2, hinting a previous infection. The team also found that a higher percentage of those who were seropositive lived with someone who had COVID-19 than those who were seronegative.

In terms of transportation, 60 percent of the seropositive cases traveled by cab or rideshare compared with 32.3 percent of those who were negative.

After the mitigation procedures to combat the pandemic were implemented, two clusters of COVID-19 cases were identified. There was a total of 15 cases. The researchers noted that two factors outside of the workplace can potentially be tied to SARS-CoV-2 infection. These include living with a household member with COVID-19 and using shared transportation.

Overall, the team revealed that though seroprevalence was low among office workers, preventing exposure in the workplace was hard between March and April 2020. More than half of those who had antibodies against SARS-CoV-2 were asymptomatic or were never tested for COVID-19. Meanwhile, about 20 to 40 percent did not comply with infection control measures, including wearing of masks and physical distancing.

Lastly, the study highlights that despite infection control measures implemented in the workplace, outside work activities and noncompliance with mitigation efforts may have contributed to the virus spread.

The study offers an interesting case study for transmission dynamics among office workers, highlighting the need for strict prevention measures in these contexts to prevent occupational outbreaks.