What is a Super-Spreader?

May 4, 2020
A super-spreader is a sick person who transmits illness more than the average infected individual. In this article, we'll discuss whey this happens, as well as its implications during a pandemic.

The coronavirus (COVID-19) outbreak continues to be a part of our present life. This situation is forcing us to become familiar with the different terminology that appears on the media. From virus detection tests, statistics, predictions, and all sorts of scientific concepts, we’ve had to interpret a great deal of epidemiological information. Meanwhile, now we’re going to take a look at one more concept: a super-spreader.

What does this term refer to? What role does it play in an epidemic?

Answering these questions is important to understand how these individuals contribute to the spread of a virus. Therefore, in the following paragraphs, we’ll go into detail regarding the meaning and implications of this term.

What is a super-spreader?

A super-spreader refers to a sick person that can infect more individuals than average. Let’s take a look at the following examples:

  • The R0–the basic reproductive rate–of coronavirus is between 1.4 and 2.5, according to the World Health Organization (WHO). This means that each infected patient will infect an average of more than one but less than two other individuals throughout the infection.
  • The SARS virus has an R0 of approximately 3. During the SARS outbreak, professionals observed the existence of super-spreaders who were capable of infecting up to 36 individuals each. In other words, the individual R0 of the illness was 10 more than 10 times higher in a super-spreader than the average infected individual.
  • At the beginning of the coronavirus COVID-19 pandemic, scientists detected cases of super-spreaders in Wuhan, China. A clear example was the patient that spread the illness to at least 16 sanitary workers.
  • More cases have appeared throughout the rest of the world. For example, a judge in New York spread the illness to more than 20 others.

The idea is clear: The basic reproductive rate only represents an average, and the individual reproductive rate of a super-spreader is disproportionate in comparison with the average R0. Now that we’ve made the definition of a super-spreader clear with the above examples, we need to examine the significance of super-spreaders during a pandemic.

A woman wearing a mask during the COVID-19 pandemic.
Patients with COVID-19 that are considered super-spreaders can infect more individuals than average.

You may also want to read: A Study Confirms Three Types of Coronavirus in the World

Super-spreaders: A statistics game

Like any natural process, the importance of these subjects is governed by mathematical theorems. Therefore, we need to delve into the world of numbers and look at the Pareto principle.

This theorem describes the statistical phenomenon by which, in any population that contributes to a common effect, there’s a small proportion that contributes to the large majority of the effect.

To make this easier to understand, let’s look at the 20/80 rule. 20% of infected individuals cause 80% of infections. Clearly, not all cases of super-spreaders respond to this rule, but epidemiologists have observed this distribution in other epidemics.

Just the same, transmission by a super-spreader can take place even if it doesn’t obey the 20/80 rule. So, what gives super-spreaders their ability to infect so many others?

Risk factors

Different theories exist when it comes to how a patient can come to infect a disproportionate number of individuals. However, the exact cause remains a mystery.

Nevertheless, here are some of the current theories:

  • Co-infection with other pathogens: The coexistence of more than one pathogen in our body may contribute to the increased transmissibility of one of the two illnesses–or both–to others. Research has shown that patients with HIV and another accessory illness displayed a greater development of this illness than those that didn’t present co-infection.
  • Weakened immune system: A weakened immune system may be unable to effectively detain the spread of a virus in our bodies, resulting in a higher viral load. A viral load that’s above average is associated with greater transmissibility.
  • An overly effective immune system: Another theory claims that the immune system of super-spreaders is so effective that they don’t even realize that they’re sick. Therefore, they carry on with their normal lives, thus spreading the disease to a greater number of others.
The fear of coronavirus.
To date, scientists are unaware of the exact reason why some individuals are super-spreaders. However, several theories attempt to explain the phenomenon.

A study published in Synapse reveals some interesting results regarding the issue. During the SARS pandemic, the study monitored both patients considered super-spreaders and normal patients. Contrary to what you may think, there were no differences in the symptomatology of each group.

Both super-spreaders and normal infected patients suffered similar effects regarding fever and lung damage. Researchers only observed one difference: Super-spreaders had to stay in the hospital longer to overcome the illness.

Find out more: How Long Will a Coronavirus Vaccine Take?

Super-spreader: A term full of questions uncertainties

Both the identification and the role of a super-spreader during a pandemic are parameters that are difficult to discern. Just the same, expert organisms emphasize the importance of identifying these individuals to prevent more contagion during a pandemic.