A study concludes that the factors of supercontagion “remain a mystery” after analyzing the main
Harvard epidemiologist Michael Mina points out that supercontagion may depend not on people’s particularities but on the moment of maximum viral load, which goes from 1,000 to 100,000 million in one day.
It explains that 99% of the SARS-CoV-2 viruses that a patient’s body has from the beginning to the end of the covid accumulate in just a couple of days
Supercontagators. We already know – this study has just confirmed – that they are playing a key role as “engine” of the pandemic. The data that indicate that a few people would be behind the majority of infections is increasingly refined, as they are carriers of the vast majority of the virus circulating in a population, at any given time. But who are they? Can we all be, at any given moment? What turns an infected person into a supercontagator?
They are questions that still have no clear answer, even those responsible for the study at the University of Colorado recognize it. “It is not known if these are special individuals capable of harboring extraordinarily high viral loads, or if many infected people experience extremely high viral loads for a very short period of time. Regardless of the mechanism, at any given time, a small number of people harbor the vast majority of virions (infective viral particles) ”. Nothing is clear about it, but it does seem that that little nuance that is repeated, that of “At a given moment” can be the key to understanding what is happening.
“Over-propagation remains a mystery”
Because, as the American scientist points out Eric Topol, At the moment, no clear factors have been seen that have to do with genetic or demographic characteristics, or with the genomics of the virus. Who, then, are these unmasked men and women?he wonders.
This recent study makes a review of what we know at the moment on this matter, and concludes that “The super spread of coronaviruses remains a mystery.” Its authors assure that “the genetic sequence of the virus, the severity of the disease and the conditions of the host – such as age, sex and health conditions – are not related to overpropagation.” So what is the key?
Possible parameters that can influence super contagion
Researchers have studied whether certain physical, biological and environmental conditions influence that provide more stability to the virus so that it can continue to be infectious, once it leaves the supposed “supercarrier”. These would be some of those parameters that can play a role, although they are only listed as “possible”.
What the virions (infectious particles) of the supercontagators are different. This may have to do with the host’s blood group and differences that affect their susceptibility to the virus and its transmission. Have some paper the microbiome, that is, the genes of that set of microscopic organisms (bacteria, viruses and fungi) present in our body that we call the microbiota. This study suggests that “the virus could bind directly to the host’s microbiota”, and that it has been seen that “nasal microbiomes can influence the efficient airborne transmission of respiratory viruses.” What physical factors optimize transmission: they ensure that “in superpropagation events, long-range transmission is likely to have something to do with it, in most cases,” referring to contagion by aerosols. Remember the study that has been shown that there are 20% of infected who expel much more aerosols than the rest. They suggest that the obese may contribute to a super-propagation event by releasing a greater amount of infective aerosols. That influence environmental conditions: the persistence of viruses in the environment depends, basically, on temperature and humidity. They influence the greater or lesser stability of the virus, and its viability. In relation to this, they assure that the greater or lesser indoor ventilation would not be defining the supercontagion events, but it is “clear that greater ventilation and reducing the indoor capacity reduces the transmission of SARS-CoV-2. Therefore, until more details are known about the supercontagators, increasing the exchange rates and air renewal is important, because it can alter the consequences of a super-propagation event ”, they warn.
But, after analyzing all these parameters, the conclusion they reach in the study is that there is no conclusion. There is still nothing clear about it. In response to this, the prestigious Harvard epidemiologist and immunologist Michael Mina contributes his own hypothesis: that what underlies these mysterious cases of supercontagion is, simply, a window of opportunity.
In the wrong place and time
“Wrong place, wrong time”, summarizes Mina on her Twitter account. “Being in the wrong place and time”. And with this, we return to the nuance that we highlighted at the beginning, when defining supercontagators: the importance of “in a given moment”.
My thought: wrong place, wrong time.
Virus load goes from 1000 -> 100,000,000,000 in a day and then drops back to 100,000 in just a few days.
If you show up to dinner, presymptomatic and in the unlucky time window wa virus load of 100,000,000,000 you might be a superspreader
– Michael Mina (@michaelmina_lab) May 12, 2021
Mina explains that “The viral load goes from 1,000 to 100,000,000,000 on the same day, and then drops back to 100,000 in just a few days.” So if, being infected, “you show up for dinner, presymptomatic, and in that” unlucky time window “, with a virus load of 100,000,000,000, it is possible that you are a supercontagator.” As simple as that. And worrying. Because Mina’s thesis assumes that we can all be supercontagators, at any given time.
99% of viruses, concentrated in the initial moments of infection
To explain his idea, he has produced a graph showing the time interval of just one or two days that a person has 99% of the SARS-CoV-2 viruses that your body will contain throughout the infection. Almost all viral load is concentrated in a minimal amount of time. This hypothesis reinforces the importance of rapid detection and the possibility of frequent self-testing (a recommendation that this expert has insisted on throughout the pandemic) so that those infected can isolate themselves as soon as possible, just at the beginning or before starting to test. have symptoms, because that’s the time with the highest viral load.
The immunologist clarifies, in fact, that the Colorado study was not suggesting that 2% of people cause 90% of transmission, but that Most infected people go through a peak viral load peak and, in doing so, contribute to that 2% over 1-2 days. Because If that moment coincides with that dinner, the union of both factors can be explosive. Mina explains it very graphically in this other tweet.
Not carried by 2% of people. But rather 2% in a given snapshot. Most infected people likely to pass through the “super carrier” state. It’s not about the person but where in the course of an infection the person is swabbed.
See this for instance: pic.twitter.com/by1NYHKySA
– Michael Mina (@michaelmina_lab) May 10, 2021
This in turn assumes that the virus detection tests would only be a “snapshot”, a still photo of the viral load that the infected person has “at that precise moment”. But it may be different hours later. This is something the authors of the Colorado study were already warning about. And that will have to be taken into account, because one may not be a supercontagator when the test is done, but hours later.
That is being a “supercarrier” has nothing to do with the person, according to the Harvard epidemiologist, but rather “with the time of infection when that person has been tested” for the virus. In fact, Mina assures that “most of those infected are” supercarriers “at some point during their infection.”