Friday, March 27, 2020

Stopping the Spread of COVID-19

In times of crisis, people become more concerned about each other. Over the past few weeks, many people have stopped me in the hallway to ask me how I am doing. I can honestly tell them that I am doing fine. I am fine because we have a great team at GBMC - experts in their fields who work very hard and who are focused on our vision.

The community needs us, now more than ever, to remain focused on our vision. Many people are scared, and they are hoping that we will be there for them if they get sick with the coronavirus (COVID-19). We are doing everything we can to manage what is in our control and we are actively creating plans for scenarios that we cannot control.

As a physician, I was trained to look for evidence to make a diagnosis - to use data to decide what to do. One of my frustrations as we deal with the pandemic is the degree of uncertainty that we are experiencing. Will we have a surge of patients and if so, when will they come? So far, we have not had a surge, but has it simply not happened yet?

I have been reviewing the epidemiology of infectious disease outbreaks. There is a statistic called the basic reproduction number (R0) or R naught. A common definition of R0 is the number of secondary cases that one case would produce in a completely susceptible population (i.e. How fast is this disease likely to spread?). Since there is no immunization for COVID-19, we believe that everyone who has not yet been infected is susceptible. An outbreak of a disease will continue if R0 is >1 and it will end if R0 is <1.

There are three primary factors that determine the contagiousness or transmissibility of infectious agents and therefore the R0. They are: 1. The duration of contagiousness of the agent (early data shows that this is about 10 days from the onset of symptoms in COVID-19); 2. The likelihood of infection per contact between a susceptible person and an infected person; and 3. The contact rate between infected and non-infected persons.

We obviously can’t do anything to change the duration of contagiousness, at least until there is a cure. We wear personal protective equipment (PPE) like face shields and N95 masks to reduce the likelihood of getting infected when we are in contact with an infected patient. These are precautions we must take, but the best way to reduce R0 to <1 is to reduce the contact rate. This is why our schools are closed, why most people have been sent home from work, and why the GBMC Fitness Center and all my favorite restaurants are closed. We have essentially shut down our economy and put large burdens on our citizens to stop the spread of this disease.

Is it working? There are some hopeful signs. The number of Emergency Department visits are down, and we have not seen a surge in cases, yet. We can’t really tell what the actual R0 is, in part because we don’t have enough test kits to test a large enough segment of our community to see who has been infected. But we must stay the course. We will overcome the coronavirus if we stay together and stick with the science. If you have questions, our Infoweb is the official source of institutional information for the COVID-19 outbreak and it is updated frequently. Please check it at regular intervals to keep yourself in the know.

Thanks to all of you for your hard work!

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