Denver Catholic

can be drawn from these studies is that if a scientist puts the coronavirus on an inanimate surface, it can be detected at some future time point by a very good and sensitive test. It does not prove that the virus can actually be transmitted that way, and to what extent this mechanism plays in epidemics. The only way one could actually prove virus transmission in this fashion would be experiments involving humans, which are clearly unethical. The CDC coronavirus webpage now states the following: "It may be possible that a person can get COVID -19 by touching a sur- face or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes. This is not thought to be the main way the virus spreads, but we are still learning more about how this virus spreads." The take-home message is that surfaces play some role in virus trans- mission, but it is thought to be a minor and secondary role. And by the way, President Trump did not force CDC to make this statement; they were just reminding us of something that has long been established in the scientific community. Secondly, we have learned quite a bit about who is dying from this virus. Let's face it, the "million-dollar question" is: What is the risk of dying from this virus if one is infected? To determine this, scientists calculate something known as the case fatality rate (CFR), which is a very simple fraction. It is the total number of deaths due to coronavirus divided by the total number of infections; all within a particular geographic region. The total number of deaths is something that can be fairly accurately determined. I know there have been reports of over and under estimations of deaths, but in my experience working with epidemics, these are a "wash." The problem in determining the CFR is getting an accurate denominator – the total number of infections within a particular area – since many people will not have any symptoms. In the early phase of the epidemic, this was completely unknown. That is why we heard various CFR estimates that were as high as three to five percent. The only way to determine the denominator in the CFR fraction (total number of infections) is by conducting what is called a serosurvey. These are quite straightforward in theory, however difficult in practice to carry out. In the most common scenario, a team goes door-to-door randomly asking for volunteers to donate a blood sample. While at CDC, we conducted one of these in Queens, NY, to determine the number of West Nile infections that had occurred; you can imagine some of the responses the team received! Once enough samples are obtained (enough to make the study statistically meaningful), they are then tested for the presence of antibody to the virus, which indicates that the individual was infected, regardless of whether or not they had any symptoms. The results of a number of these serosurveys for COVID -19 have now become available, and the resulting CFR calculations are significantly lower than originally predicted. In fact, CDC just recently released results where they have determined that the overall CFR in the USA is approximately 0.26 percent. This is approximately twice the CFR of our annual flu epidem- ics. Another very informative way to look at this data is to determine the CFR among different age and health status categories. New York provides a large data set to perform this analysis, and when the CFR is determined for various age & health categories, these data show us fairly accurately the 14 DENVER CATHOLIC | JUNE 13-26, 2020

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