Wednesday, July 1, 2020

The epidemic in the US: a comment by the virologist Guido Silvestri

Many have noted the spike in the number of coronavirus cases observed in the United States. The fear is, obviously, that this increase will result in a corresponding spike in the number of deaths after some delay. The virologist Guido Silvestri wrote a comment in Italian on Facebook about the situation and I thought it was interesting to translate it in its entirety and post it here. This translation is made by smoothing a Google-translated text and it remains rough, but I verified that it maintains the meaning of the original. This text was written a few days ago and, so far, we saw no large changes in the trends of cases and deaths in the US. But, as Dr. Silvestri himself says, we need to wait a few more days in order to see if the spike will continue and result in an increase in the number of victims. On this subject, see also this post by Chuck Pezeshky.

Update of July 2nd, 2020. The trends are still the same: the number of new cases keeps growing, but the number of deaths goes down. It seems to disprove Silvestri's hypothesis 1, the other three remain possible

By Guido Silvestri

Many ask me to talk about the situation of the COVID-19 epidemic in the US. I try in these lines to start from the data, without making political considerations. Science, always science, and very strongly science, as you and I like it :)

First of all, I would start from the curve that you see in the graph, above. Today (28 June), it was the second-highest day in terms of number of cases (yesterday was the highest ever). So it is clear that we are in full pandemic with many new cases diagnosed, especially in the large southern states (CA, TX, AR, FL, GA etc). Not that it is a subject not discussed at length, but it is good to start from these data.

It is equally clear that we are not experiencing the Apocalypse. In fact, if you look at the graph of daily deaths (above, lower graph) you can see that today was the 85th worst day since the beginning of the epidemic - which is not so bad since everything started here early March 2020. As far as I know, there is also no sign of the hospital overload seen in the past in Wuhan, Lombardy, New York / New Jersey, and other places.

The question asked by those who try to understand the facts (and do not have pre-packaged and/or ideology-driven answers) is the following: since we are facing this massive increase in cases that has lasted for ~ 3 weeks, why there is no corresponding increase in deaths or seriously ill people?

Of course, I don't have the absolute answer (and in fact nobody has it), but let me try to make some hypotheses and comments.

Hypothesis # 1. There will be a surge of deaths in the coming days. It is possible, of course, and we will see that in the next few days (so I already anticipate that in a week we will return to this discussion). I would point out, softly, that, looking at the graphs of last March, the time gap between increase in cases and increase in deaths is ~ 1 week. I repeat: we'll see.

Hypothesis # 2. Many diagnoses (i.e., positive swabs) are being made in asymptomatic and/or young subjects and therefore less at risk of developing severe forms of COVID-19. It is difficult to find precise data in this regard, but the feeling of many is that this is an important point, especially if the feared surge of deaths does not occur. If confirmed, this aspect would open up interesting implications in terms of natural immunity.

Hypothesis # 3. Positive swabs have a lower viral load, as it was already demonstrated in Italy first by the group of Massimo Clementi and Nicasio Mancini at the San Raffaele hospital and then by others (Pavia, Treviso, etc). This in turn could be linked to environmental factors (many infections in the South) and/or seasonality, which favor infections caused by lower viral inoculation. I would like to remind readers that lower inoculation infections = less serious infections, as known from the animal model of CoVs

Hypothesis # 4. Patients have a better prognosis because we treat them better. This point, in my opinion, is important and, if confirmed, goes in the direction of putting COVID-19 among the diseases with which the health services are concerned, without asking the general population to upset its existence - which, then, to think about it well, they are all other diseases. It seems clear to me that between dexametazone, tocilizumab, baricitinib, remdesivir, convalescent plasma, anticoagulant therapy, better ventilation protocols, etc. we are much more effective in treating the infection today than 3-4 months ago. This is important and a harbinger of optimism.

I add: note that I have not even mentioned the possibility of a virus-host adaptation, which is very plausible for me, because I do not want the scandalized chorus of some "purists" to say that it is too early to make this hypothesis ((but not other hypotheses) :-)

For now, therefore, I leave you with a key question, some preliminary hypotheses for an answer, and an appointment next week, to see if at that point we will have clearer ideas of what is going on.


Dr. Guido Silvestri received his MD in Ancona, Italy, and completed Residency training in Internal Medicine & Clinical Immunology (Florence 1990) and Pathology (U. Penn 2001). He is currently a Georgia Research Alliance Eminent Scholar in Comparative Pathology, and Professor and Vice-Chair of Pathology and Laboratory Medicine at the Emory University School of Medicine, where is also serves as Chair of the Division of Microbiology & Immunology at the Yerkes National Primate Research Center. 


Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)