INSIGHT: An Epidemiologist’s Look at COVID-19

By Chris Li, MD, PhD

Full Professor, Division of Public Health Sciences | Faculty Director, Office of Diversity, Equity & Inclusion [Fred Hutchinson Cancer Research Center], Trustee [Eastside Preparatory School]

One of the small benefits of the pandemic for me has been that when people ask me what I do I no longer need to explain what an epidemiologist is. At its essence epidemiology is about figuring out why certain numbers are what they are. In my field of cancer, this can be trying to understand things like why do some women have a high risk of aggressive, lethal breast cancer while others do not; why do Alaska Natives have rates of colon cancer that are more than double that of the general U.S. population; and how can we reduce the false positive and false negative rates of cancer screening tests? The COVID-19 pandemic has broadened the public’s understanding of how we track, measure, and understand the impact of disease; data are available everywhere we look. As an epidemiologist I am often asked about where I think we are in the pandemic and how I track it. I want to emphasize that I am not an infectious disease expert, but I thank Terry Macaluso for this opportunity to share my thoughts. Below are some of the websites that I regularly monitor:

King County COVID dashboard: Like I imagine is true for many of you, every Monday-Friday I refresh this site for the latest local data. Each indicator provides a different piece of useful information, but the ones I focus on are the trends in new reported cases and hospital bed occupancy. This first metric is important because a rate <25/100,000 is often cited as a threshold for when places like high schools could safely reopen. Hospital bed capacity is also critical as we are seeing regions across the country where hospital capacities are being exceeded, impairing our ability to treat not just COVID patients, but also patients with other diseases – heart disease, cancer, injuries, etc.
UW Virology: Well publicized is the use of the % of COVID tests that are positive in decision making as this has been a key metric used by New York City to determine if its public schools should be open or closed (their goal has been <3%). UW is one of the major local COVID-19 testers and their test is one of the most accurate available. As of December 4 this positivity rate is 10.3% where the desired King County metric is a rate <2%. These data indicate that not only are we testing as many people as we ever have, the positivity rate is also one of the highest it has ever been.
UW’s Institute for Health Metrics and Evaluation (IHME): The IHME COVID model, widely cited in the media, is a statistical model that uses various inputs to project the future course of the pandemic. For me this is one of the scariest numbers to look at because I have only ever seen their projected number of COVID deaths go up. When first published in May, it projected a little over 60,000 COVID deaths which at the time felt like an incredibly high number. It currently estimates that the total number of U.S. COVID deaths will nearly double from the ~270,000 we have had to date to 538,893 deaths by 4/1/2021. If this holds, it will put COVID neck and neck with cancer as the second leading cause of death in the U.S. over the past 12 months (after heart disease). That total will exceed the total numbers of deaths due to the third, fourth and fifth (accidents, lung disease, and stroke) most common causes of death in the U.S. in 2018 combined.

While all signs point to the pandemic further worsening over the next few months (based on the current spread of the virus, increased time indoors with colder weather, and anticipated travel and gatherings over the holidays), there is finally some light at the end of the tunnel. The COVID vaccines that have been developed have wildly exceeded all expectations. When discussing the prospects of a vaccine several months ago the biggest question for me was whether we were going to have a vaccine with the effectiveness of a polio vaccine (99-100% effective, essentially eradicating the disease), or a vaccine like the seasonal flu vaccine which over the past several years has ranged from 19-52% effective (which would dampen but not quickly end the pandemic). Fortunately, we are much closer to the former than the latter given the 95% effectiveness of the two leading vaccines.

While the end is in sight, for now and even once immunization begins, we all need to continue to do everything we can to slow the spread of COVID. This is particularly challenging as we enter winter break and the holiday season, but we all can and need to continue to do our part by wearing masks, maintaining physical distance, not gathering in groups, and avoiding travel that is not essential.

What I have deeply appreciated about EPS is the leadership it has shown since the very beginning of the pandemic. EPS has made difficult decisions that are driven not only by science but have also been in the interests of protecting the safety of those both inside and outside of our community. In the coming weeks we may see further state and federal restrictions, but I will note that the new CDC recommendations are prioritizing efforts to open K-12 schools to the extent that is safely possible saying that schools should be “the last settings to close” and “the first to reopen.” As a Trustee, I have seen how EPS has clearly established the infrastructure to rapidly implement a variety of measures when it does become possible for the school to safely reopen. I am deeply appreciative of every member of the EPS team of administrators, faculty, and staff who have gone above and beyond in their efforts to deliver the school’s mission during this challenging time.