Modeling transmission dynamics and effectiveness of worker screening programs for SARS-CoV-2 in pork processing...

Area of Science:

• Epidemiology
• Occupational Health
• Mathematical Modeling

Background:

• Pork processing plants were identified as SARS-CoV-2 hotspots in Spring 2020, leading to significant occupational health, financial, and animal welfare crises.
• The swine industry faced unprecedented challenges due to widespread viral transmission within processing facilities.

Purpose of the Study:

• To describe the epidemiological situation of SARS-CoV-2 within pork processing plants.
• To develop mathematical models simulating viral transmission dynamics.
• To evaluate the effectiveness of routine PCR screening in reducing SARS-CoV-2 circulation.

Main Methods:

• Collected epidemiological data on clinical disease incidence and antibody prevalence across three processing plants.
• Developed a mathematical transmission model incorporating asymptomatic, pre-symptomatic, and community transmission.
• Calibrated the model to observed data to estimate the initial reproduction number (R) and simulate various screening scenarios.

Main Results:

• Clinical disease incidence ranged from 2.5% to 25%, with antibody prevalence at 30% to 40% during larger outbreaks.
• Initial reproduction number (R) was estimated between 2 and 4, declining to ~1 within weeks due to biosecurity and immunity.
• Routine PCR screening every three days averted 25% to 40% of clinical cases, significantly more than testing every 14 days (7% to 13%). Testing frequency was more impactful than result delays.

Conclusions:

• Frequent PCR screening (every three days) is effective in minimizing SARS-CoV-2 spread in processing plants, though less effective in preventing initial large outbreaks.
• Model insights on testing frequency are generalizable to other high-density work environments.
• This research provides protocols to enhance occupational safety and business continuity in processing plants.