Obtain the data you need to make the most informed decisions by accessing our extensive portfolio of information, analytics, and expertise. Sign in to the product or service center of your choice.
The lack of distance between workers was among the top risk
factors for the spread of COVID-19 at a Smithfield meat processing
facility in South Dakota, according to a report from the US Centers
for Disease Control and Prevention (CDC).
The report detailed the South Dakota Department of Health's
(SDDOH) investigation of a COVID-19 outbreak that began March 24
that sickened 929 workers and a further 210 people who had contact
with those infected. The 929 infections among workers accounted for
25.6% of employees at the plant. At the peak of the outbreak new
infections reached an average of 67 per day, the report noted. In
all 48 patients were hospitalized (39 of them plant workers) and 2
died (both plant workers).
SDDOH began its investigation March 24, after the first case was
reported after an employee reportedly began to show symptoms March
16 and was tested March 22. The test revealed the employee was
infected with SARS-CoV-2, the virus that causes COVID-19. CDC
joined the investigation April 15.
As a result of rising cases, the facility implemented a phased,
temporary closure April 12.
COVID-19 patients from the facility were ordered to
self-quarantine after diagnosis. Those who had contact with those
positive for COVID-19 were traced, instructed to quarantine and
were monitored for signs and symptoms of illness. On April 3, the
facility began "began screening all employees for fever, installing
physical barriers on the production line, and amending the employee
dress code to include optional masks, which were required as of
April 13."
Among employees infected with COVID-19, the median age of those
hospitalized was 60, with a median length of hospital stay of 6.5
days.
COVID-19 contact exposure was defined as "as persons who were
within 6 feet of an employee who had a positive SARS-CoV-2 test
result for at least 5 minutes during the employee's infectious
period (i.e., from symptom onset to discontinuation of isolation),"
the report said. The infectious period definition was expanded
April 1 to include "persons who had contact with persons with known
COVID-19 during the 48 hours before symptom onset, in accordance
with changing CDC guidance."
Factors contributing to COVID-19
transmission
The outbreak at the plant "highlights the potential for rapid
transmission of SARS-CoV-2 in these types of facilities," the
report said. Factors that might have contributed to the spread of
COVID-19 at the facility "include high employee density in work and
common areas, prolonged close contact between employees over the
course of a shift, and substantial SARS-CoV-2 transmission in the
surrounding community," according to the report.
The highest attack rates were seen in the Cut, Conversion and
Harvest department-groups, CDC said, noting that in those
departments' employees tended to work less than 6 feet apart.
Meanwhile, it found attack rates were higher among wage employees
than salaried ones, suggesting the latter group "typically had
workstations that could be adjusted to maintain distancing and did
not work in close proximity to other employees on the production
line," which may have reduced their risk of contracting the
virus.
Those differences in attack rates "highlight the importance of
engineering controls (e.g., physical barriers) and administrative
controls (e.g., cohorting employees) in mitigating the risk for
SARS-CoV-2 transmission in meat processing facilities," CDC said.
It also noted that "consistent and correct use of masks" can also
reduce transmission of the virus.
The outbreak rapidly spread beyond an initial three departments,
which CDC speculated may have been facilitated via cross-department
contact in common areas including cafeterias, locker rooms and
equipment-dispensing locations. However, some cases may have been
linked to transmission that occurred because of employee contact
outside the facility including carpooling, cohabitating and
socializing outside work, the report acknowledged.
Based on those findings, CDC suggested that signs encouraging
physical distancing and staggered shifts/breaks "might reduce risk
for transmission among employees in these areas."
While physical distance may have been a factor in differing
attack rates across departments, CDC said that despite different
employee densities across the three shifts, it found "similar
attack rates." It also noted that third shift employee duties
already entail physical distancing and the use of personal
protective equipment, but said similar attack rates seen among
those employees "might have occurred in common areas or outside the
facility."
Following the phased closure of the plant, "cases among
employees declined to approximately 10 cases per day within 7 days
of facility closure," the report found, though some decrease in
cases was also observed before the plant shuttered, it noted.
Control measures like physical distancing that were implemented
before the closure "might have contributed to this decrease," it
said.
Caveats in the data include the limited characteristics
available to calculate attack rates (department-group, shift and
compensation status), a lack of race and ethnicity data, limited
testing of asymptomatic persons and a "likely" underestimation of
COVID-19 cases in the community population, CDC cautioned.
Most cases symptomatic
Of the 929 COVID-19 infected employees, 96.3% were symptomatic.
During the March 16-April 25 period SSDOH and CDC found that plant
employees accounted for 920 (41.8%) of the 2,199 cases identified
in the surrounding community.
The analysis excluded employees who did not work between March 2
and April 25, and data was aggregated based on department: Bacon,
Conversion, Cut, Harvest, Sausage, Smoke meat and Other. Attack
rates were calculated by shift, department-group and compensation
status.
At the plant, two shifts harvest and process animals while a
third sanitizes the facility, the report noted.
Infection mitigation recommendations
Based on the analyzed data, CDC laid out a set of proactive
recommendations that if implemented "before, or soon after" the
introduction of COVID-19 to a plant might "substantially reduce the
risk" for COVID-19 spread among employees:
Engineering, including modification of workstations to separate
workers
Administrative, including promoting social distancing when
possible
Correct and consistent use of masks
Prompt isolation of infected employees and contact tracing once
a case is identified
No one control measure "likely will eliminate transmission" CDC
warned, encouraging a multi-faceted approach to control and
mitigation. Even when comprehensive measures are implemented, it
acknowledged that should widespread transmission occur, plant
closures may still be needed to curb transmission among employees
and their contacts.
The report was published in the August 7 release of CDC's weekly
Morbidity and Mortality Weekly Report (MMWR).
Posted 11 August 2020 by Richard Morrison, Writer/Editor, IHS Markit
