Q&A with Infectious Disease Modeler Natasha Martin

UC San Diego’s plan for the fall quarter is continually evolving, informed by the university’s Return to Learn program. We invited students, faculty and staff to submit their questions, including inquiries about the overarching goal of the program, the role of testing in preventing a major outbreak, how viral transmission is being monitored, and more.

To address several of these important topics, we spoke with Natasha Martin, associate professor of medicine at UC San Diego School of Medicine and one of the Return to Learn project leads.

As an infectious disease modeler, Martin develops epidemic models that help the university better understand transmission risk on campus. Through quantitative analysis, she integrates different data pieces to inform decisions about how to identify and mitigate potential outbreaks. This process is ongoing, allowing the Return to Learn program to be adaptive.

Q. How does the Return to Learn program work?

A. The Return to Learn program has three pillars that are central to our strategy to resume on-campus activity in the fall.

1. Reduce transmission. By requiring face masks, using personal protective equipment, enhancing sanitation and restructuring the configuration of the campus in terms of housing and classroom density, we aim to significantly reduce the risk of transmission.
2. Monitor viral activity. We want to detect outbreaks at their earliest possible stage so that we can intervene. This includes daily symptom screenings of employees and students coming to campus; symptomatic and asymptomatic testing; and wastewater monitoring. These tools will hopefully allow us to understand where viral activity is happening on campus, and do more testing to determine the extent of a potential outbreak.
3. Public health interventions. Our program strives to ensure that students living on campus with COVID-19 are provided support and a place to isolate, and that contact tracing is performed.

Finally, our approach will be adaptive. We will continually monitor the data and adjust our approach as we receive new data and if circumstances change.

Q. What type of testing is planned for the fall?

A. We want to make it easy for students, faculty and staff to get tested. For asymptomatic testing, we envision placing testing boxes around campus. Starting in the fall, our plan is for asymptomatic individuals to be able to test themselves without having to come to the student health service, a physician’s office or the hospital. Each will receive a collection sample bag and will either swab their own nose or mouth, then return the sample to a collection container. We know people prefer to have saliva testing, and we are working on getting this option validated so that we can offer it in the fall. Test results will be delivered directly to the individual’s mobile phone through the MyChart app. Under most circumstances the results will be available within 24 hours.

I want to reiterate that asymptomatic testing is just one part of a broader framework that we are implementing. These tests are happening in coordination with daily symptom screenings for employees and students; environmental monitoring such as wastewater and surface testing; interventions like masking and lowering the campus density within housing and classrooms; and case isolation and contact tracing. Together, these strategies help us identify viral activity on campus and reduce the risk of widespread transmission.

Q. When will asymptomatic testing begin?

A. We’ve already begun testing some employees reporting to campus. Students will be tested in a staggered approach as they arrive on campus when they move in. After that point, we will start our ongoing testing program for all on-campus community members. On-campus community members are encouraged to take part in asymptomatic testing as a collective public health program that will help us resume on-campus activities as safely as possible.

We acknowledge that UC San Diego is not an island. We want everyone who is coming to campus to be tested. There are some populations for which we may recommend increased testing, for instance those who cannot socially distance or appropriately mask. But one thing that I want to underscore is that our approach is adaptive. We will adjust our strategy on who we test and how frequently we test based on the viral activity we find during our ongoing monitoring.

Q. How have you used modeling data to shape the UC San Diego fall plan?

A. The goal of our asymptomatic testing program is to enable us to detect outbreaks at their earliest stage so that we can intervene and prevent them from growing. Our simulation models have helped us understand that we have a high likelihood of detecting an outbreak before there are 10 detectable infections if we test at least 75 percent of the population on campus every month.

The program is designed to be adaptive, based on data as it emerges. For example, it may be more effective to test some populations more or less frequently based on their particular likelihood of infection and their potential impact on the campus based on the number and variety of people they come into contact with.

We've also done other kinds of simulation models tailored to understanding certain campus operations, such as the impact of housing density as well as classroom sizes. For example, our modeling indicated that we would see a very strong reduction in transmission if we put a maximum cap of classroom size at 50 and shifted many of our courses online. This will substantially help to reduce the risk of transmission if an infection occurs on campus.

Q. Can you describe how wastewater testing will happen?

A. Wastewater testing is part of our strategy of trying to monitor viral activity on campus to detect outbreaks early. One of the things that we are interested in is whether monitoring wastewater and sewage, for example within residential housing, can give us an early indication that there are some infections occurring there, potentially earlier than our asymptomatic testing program. If we identify viral activity in the wastewater of a dorm, we can then go into the building to perform more extensive testing. This will allow us to identify who is infected and conduct appropriate contact tracing and quarantine of contacts.

Q. How is UC San Diego working with and being guided by county and state recommendations?

A. We're working closely with the county and state to ensure that all of our activities are in alignment with their recommendations, their orders and their policies. This is occurring on a number of levels, including the testing that we provide and the symptom screening, as well as the sanitation and other activities on campus to reduce the transmission risk. We're really working hand in hand to ensure that we are following guidelines but also enhancing them with our own understanding of how we can better target and reduce risk on campus and identify outbreaks early.

Have more questions? We invite the campus community to submit your inquiries online. A new Q&A with a Return to Learn expert will be published each Thursday in This Week @ UC San Diego for the next 15 weeks.