Estimating Preventable COVID19 Infections Related to Elective Outpatient Surgery in Washington State: A Quantitative Model

Yuemei Zhang; Sheng-Ru Cheng

We assume that since the majority of patients and HCWs reside in WA, their infection statuses would initially also be representative of that of the general WA population. Thus we multiplied our ratio with 3047 total patients per day and 2742 total HCW to arrive at the initial values of 0.18 asymptomatic infected patients per day, 3046.82 uninfected patients per day, 0.16 asymptomatic infected HCW, and 2741.84 uninfected HCW. Asymptomatic infected HCW were further subdivided into groups based on how long they had been infected. Because asymptomatic COVID19+ individuals would remain in the workforce, we included infected HCW in the perioperative workforce for days 1-4 of their infections (during which time they could also infect other HCW and patients), and then removed them from the workforce once they reached day 5 and displayed symptoms. For our initial conditions, we divided asymptomatic infected HCW evenly into . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Since we are interested in the total infection spread, data for some known infected population, both symptomatic and asymptomatic, is required. For this, we used data extracted from the Diamond Princess cruise ship, 27 since the close quarters approximate the perioperative setting. Due to the isolated nature of the ship, health officials were able to test everyone onboard the cruise ship, even if there are no symptoms evident. Using the data at hand and the equation above, we can readily determine the transmission constant by dividing the number of new cases at time t + 1 (with time measured in days) by the product of infected population at time t and the uninfected population at time t, which we calculated to be an average of k = 1.219e-4.