Super Contagiator: What Is It And What Are The Causes?
The Coronavirus pandemic continues to be a part of our life, forcing us to familiarize ourselves with some terms. From screening tests to rates, to predictions and statistics, we find ourselves having to interpret a vast amount of epidemiological information. Today we talk about a new definition: the super contagiator.
What does it mean and what role does it play in this epidemic? Answering these questions is important in understanding how it contributes to the spread of the virus.
What is a super contagiator?
It is defined as a sick person capable of infecting a higher number of people than the average. Let’s take an example:
- The R0 value of Coronavirus (the basic reproduction number) is between 1.4 and 2.5 according to the WHO. This means that each infected person, in the course of the disease, can infect more than one person on average, but less than three.
- The SARS virus had an R0 of about three. But even during this epidemic, super contagiators capable of infecting up to 36 people have been identified. That is, in these subjects the individual reproduction number of the disease was 10 times higher than in the other patients.
- Cases of super contagiators had already been observed in Wuhan, China. A clear example, the patient who transmitted COVID-19 to at least 16 healthcare workers.
- There are other cases in the rest of the world. In New York, a judge infected 20 people.
One concept must be clear: if the R0 represents an average, the individual contagiousness index of a super contagiator is excessive. Once the term is defined, it is equally important to understand the role of super-contagiators during a pandemic.
You may also be interested in: Patient zero: research during the pandemic
A statistical game
Like all natural phenomena, this too is explained by a mathematical theorem. It is necessary to enter the universe of numbers with the Pareto principle. According to this theorem, in any dynamics in which there is a cause and an effect, it is only a small portion of the causes that contribute most to the final result.
It’s the 20/80 rule. In this case, 20% of infected people cause 80% of infections. Clearly, not all cases of super contagion meet this rule, but it is a distribution already observed in other epidemics.
There is talk of super contagiator even when the 20/80 ratio is not met. But why does it happen?
Risk factors
There are several theories as to why a sick person can infect such a large number of people. The precise cause, however, is unknown.
- Co-infection with other pathogens. The coexistence of more than one pathogen can lead to a greater transmissibility of one or more of them to other people. HIV studies conducted on patients with other ancillary diseases have shown that the disease is more aggressive than the average.
- Immunosuppressed people. A weakened immune system may not be able to effectively block the spread of the virus within the body, increasing its viral load. A higher than average viral load is linked to a higher transmission capacity.
- Overreactive immune system. Another possibility is that the infected person’s immune system is so reactive that the disease goes unnoticed. In this way it is easier for the sick person, leading a normal life, to infect a large number of people.
Research published in the journal Synapse offered interesting results. During the SARS pandemic, monitoring was initiated: patients considered super diffusers vs normal patients. Contrary to popular belief, no differences in symptoms emerged in the two groups.
Both the super contagiators and normal patients had the classic effects of the disease such as fever and lung damage. Only one difference was observed: a longer hospital stay was required for the super contagious patient.
Super contagiator, a definition full of unknowns
Identifying and understanding the role of the super contagiator in this context is a complex job. However, health organizations stress the importance of identifying these individuals to prevent further infections in pandemic situations.
