'Warning Lights' Ahead: Insights From COVID Epidemiology

Paul G. Auwaerter, MD


October 29, 2020

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This transcript has been edited for clarity.

Hello. I'm Paul Auwaerter with Medscape Infectious Diseases, speaking from virtual IDWeek and Chasing the Sun, a 24-hour event that attempts to capture the incredible amount of information [on COVID-19] scientifically and clinically, and how the pandemic has affected different countries across the globe. Today I'd like to focus on the epidemiology.

The COVID-19 Dashboard

Dr Lauren Gardner was one of the first speakers, and she is one of the forces behind the creation of the Johns Hopkins COVID-19 data tracking map that many of you may be familiar with, which tracks not only cases but also deaths.

I was impressed, mainly because this came together so quickly. There were scant resources, with many manual components early on in the building of this dashboard, which has undergone many refinements.

She spoke to some of these refinements, including adding more maps, such as case incidence rates that help in terms of normalizing per populations to give a better sense of how significant the virus might be in a certain region. They added smaller maps on a county level so that people have a better sense of what's happening in their community and can try to understand whether they should be ratcheting up their mitigation efforts.

Dr Gardner also bemoaned the lack of standardization. It's been made much more difficult because different countries have different reporting methods. Attempts made by the Johns Hopkins team to correct for errors have obviously taken a great deal of time, but the reliability has improved.

For example, the CDC has taken this information and has now incorporated it into their own forecasting models as well as other modelers. Dr Gardner has been a modeler and is most interested as a data user rather than a data assembler. We're so glad and lucky that she stepped into the breach.

These improvements are no doubt continuing, but she signed off with an important message that I hope many of us, including public health officials and politicians, will take from this pandemic: If we are ready ahead of time with a hypothetical virus or other infectious illness that has such impact, we would be far better prepared and able to use standardized data, open data, and principles with transparency to help guide early policymaking.

Insights From Surveillance

The next talk was from Aron Hall from the CDC. He started off talking about the first 12 cases of COVID-19 in the United States and looked at some of their early work. They determined that viral carriage goes beyond clinical infectiousness, for example, as they were only able to find infectious virus in people 10 or less days after symptom onset.

He spoke about the complexities of contact tracing and the important point that members of households seem to be at highest risk — with a percentage in the teens — of acquiring the disease. That's where I think more efforts could be directed for household investigations as opposed to wider ones, if resources are limited.

By July, there were maps showing that most seroprevalence sites across the United States were well under 10%, with the exception of areas in the New York City metro area. That still probably reflects anywhere from two to seven times the amount of actual confirmed and reported cases. I think this is no surprise that, despite best efforts, even in a pandemic, not every person who's infected is getting diagnosed.

There's a nationwide program in place that showed — at least with the data presented up to August 12 — that the seroprevalence rates varied in parts of the country from 0.4% to 23%. I think this speaks to the fact that in terms of herd immunity, we still have far to go, and that of their testing sites, 46 of 49 rest under 10%.

Clearly there are still large amounts of vulnerable populations, which are especially important nowadays as we see these numbers climb. There's also some setup for active surveillance (instead of passive surveillance), especially with hospitalizations, that may give us a better handle in this regard.

I think the epidemiology is clearly an area that is being watched with much interest. It informs the aspects that are important for our public health officials and politicians, who are hopefully working together to make the best choices for protecting vulnerable people and in trying to staunch the pandemic as we head into the fall and winter months, which I think are flashing some very important warning lights already as of late October 2020.

Thanks very much for listening.

Paul G. Auwaerter, MD, is a professor of medicine at the Johns Hopkins University School of Medicine and clinical director of the Division of Infectious Diseases. His areas of clinical expertise include Lyme disease, Epstein-Barr virus, and fever of unknown origin. He has been a Medscape contributor since 2008.

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