COVID-19 Forecast for El Paso County — Aug. 3

Plus, our resident microbiologist on surveillance testing

Good morning, and happy Monday. On this pre-pandemic date last year, rodeo lovers were attending the second day of the Ride for the Brand Championship Ranch Rodeo in Colorado Springs. The pandemic forced organizers to cancel the 2020 rodeo. (But speaking of Colorado pandemic rodeos, maybe you heard about this?)

Today, Phoebe Lostroh returns to give her weekly COVID-19 forecast for El Paso County and to explain what surveillance testing is and how Colorado College might use it this fall. Lostroh is a professor of molecular biology at Colorado College on scholarly leave who is serving as the program director in Genetic Mechanisms, Molecular and Cellular Biosciences at the National Science Foundation.

➡️ICYMI: On Friday, we explained the college’s updated testing policies for students returning to campus this fall. We also rounded-up recent announcements from other colleges and universities in Colorado about their fall plans.  

Phoebe’s Forecasts

NOTES: These forecasts represent her own opinion and not necessarily those of the National Science Foundation or Colorado College. She used the public El Paso County dashboard for all data. Lostroh prepared these forecasts on Aug. 1.   

⚖️ How her predictions last week shaped up: Aug. 1 is the last day of Morbidity and Mortality Weekly Report week 31 in the national public health calendar. It is the 21st week since the first case was detected in El Paso County. Since March 13, 137 El Paso County residents have died of COVID-19. Two weeks ago, Lostroh forecasted 4,662 cumulative reported cases for July 31 and instead, we have 4,615 cases.  

There is increased uncertainty in the data from one to four days ago, so Lostroh used two curves to forecast this week. The first one is based on the most recent seven points, July 25-31. The second one is based on the most recent 21 points with July 31 as the last day.

Predicted cumulative reported cases in El Paso County

🗝️ Key points: New cases are accumulating three times faster now than they did for the first 136 days of the local outbreak. Our average hospitalization rate for the past month is 6.3%, and if people stay in the hospital for about two weeks, El Paso County can expect about 80, 90, and 100 hospitalized COVID-19 patients in each of the next three weeks.

Number of newly-reported cases in intervals of the same length since the beginning of the local outbreak

Forecast for COVID-19 cases in El Paso County through Sept. 1

🗝️ Key points: You can see the effect of the stay-at-home order in flattening the curve using this type of graph.

Projected cases relative to local education-related dates

🗝️ Key points: Her seven-day curve predicts 7,405 cases the first day of classes at Colorado College on Aug. 24, which is about 2,800 more cases than El Paso County has today. 

14-day incidence annotated with the state’s viral spread thresholds

🗝️ Key points: The Harvard Global Health Institute defines four stages of spread relevant for opening schools:  

• Green: less than one daily new case per 100,000 people 

• Yellow: 1-10 daily new cases per 100,000 people

• Orange: 10-25 daily new cases per 100,000 people

• Red: more than 25 daily new cases per 100,000 people

Because of delays in reporting, these values are usually tracked using 14-day rolling averages. El Paso County has exceeded the “high viral spread” threshold since July 10, and Lostroh predicts the county will continue exceeding it.

14-day rolling average of daily new cases per 100,000 people in El Paso County

🗝️ Key points: El Paso County was in the yellow zone from March 23 to July 20 and has been in the orange zone since July 21. Lostroh predicts the county to still be in the orange zone when Colorado College begins Block 1 on Aug. 24. Lostroh recommends that CC should not hold face-to-face learning until El Paso County is in the safer yellow condition.

So, how prevalent is COVID-19 likely to be in Colorado Springs on Aug. 24, the first day of Block 1?

Aug. 24 is still more than three weeks away. If Colorado Democratic Gov. Jared Polis’ mask mandate and order to stop serving alcohol at bars after 10 p.m. have a substantial effect on the accumulated cases (doubtful), then Lostroh’s predictions might be too pessimistic. As of right now, Lostroh’s curve predicts increasing cases and increasing 14-day rolling incidence.

Q-and-A with Lostroh: Our resident microbiologist on what you need to know about ‘surveillance testing’

This interview has been edited for length and clarity.

CC COVID-19 Reporting Project: Colorado College is planning to conduct “surveillance testing” this fall. What does that mean, and how might the college do it? 

Lostroh: Surveillance testing is testing a random segment of the population regularly. And the reason that’s so important is that about 40% of the cases that arise are arising from contact with somebody who doesn’t have symptoms. So it’s a way to catch asymptomatic cases that have such high viral loads in their noses or mouths that they are probably spreading. What it allows you to do then is to do quick contact tracing and isolation so you can keep the cases low.

The reason CC doesn’t know yet what kind of surveillance it will be is that you have to make decisions like: Are you going to sample 3% of the population every day? Or 5% of the population every other day? Or 50% of the population once a week? Or those sorts of things. … And I know it sounds like when you read the news, ‘Oh it’s just a PCR test. Well we learn to do PCR in our biology lab, so why can’t the CC biology department just, you know, do PCR on all of us?’ And it sounds like a simple thing, but it’s actually a full-time job for a team of four or five people to test a population our size to do surveillance testing with all the logistics, all the sampling, all the de-identifying samples, re-identifying them to trace the positives — it’s a giant job. And so it’s not a job that a professor or a staff person could do on top of their regular duties. The other thing about surveillance testing is that it's really only useful if you have a quick turnaround time. There’s no point in testing asymptomatic people if they don’t get their results back for seven days.

CCRP: What are the possible benefits of some policies at other colleges that plan for frequent testing as students arrive and during the semester? 

Lostroh: They’re trying to catch, like, what if you were exposed on the day that you traveled? Then, if you get sampled when you arrive, you won’t really have enough virus in your nose that it could be detected even though you actually are about to become positive. So what they’re trying to do is catch those cases before classes start.

The mathematical modeling of whether that’s beneficial or not kind of depends on what kind of model you run. I think the science advisory group is working on that ... but you know it’s so frustrating. There should be a national policy on testing and surveillance testing — ‘we’ve tested all these options or we’ve simulated them using the best models that we know of, and the best way to do it is the following, so this is what you should all do.’ But here we are in August, and there’s still no national recommendations for these really important things.

About the CC COVID-19 Reporting Project

The CC COVID-19 Reporting Project is a student-faculty collaboration by Colorado College student journalists Miriam Brown and Arielle Gordon, Journalism Institute Director Steven Hayward, Visiting Assistant Professor of Journalism Corey Hutchins, and Assistant Professor of English Najnin Islam. Work by Phoebe Lostroh, Associate Professor of Molecular Biology at CC and National Science Foundation Program Director in Genetic Mechanisms, Molecular and Cellular Biosciences, will appear from time to time, as will infographics by Colorado College students Rana Abdu, Aleesa Chua, Sara Dixon, Jia Mei, and Lindsey Smith.

The project seeks to provide frequent updates about CC and other higher education institutions during the pandemic by providing original reporting, analysis, interviews with campus leaders, and context about what state and national headlines mean for the CC community. 

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