Catch Me if You Can: Superspreading of COVID-19

Abstract

While significant insights have been gained concerning COVID-19, superspreading of coronaviruses remains a mystery. The vast majority of cases have been linked to a relatively small portion of infected individuals. Yet, the genetic sequence of the virus, severity of disease, and underlying host parameters, such as age, sex, and health conditions, are not clearly driving the superspreading phenomenon. In this commentary we discuss what is known and what is not known about coronavirus superspreader transmission and explore whether characteristics of the virion, the donor, or the environment contribute to this phenomenon.

Keywords: COVID-19; Coronavirus; SARS-CoV-2; superspreading; transmission.

Figure 1

Superspreading in the Context of Coronaviruses. While coronaviruses such as severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have a low R₀ for most patients (<1), about 10% of patients have been found to be superspreaders (red circles), accounting for >80% of infections associated with coronavirus outbreaks. Factors that contribute to superspreading are unknown but are not due to changes in viral RNA sequence or severity of disease in the host. Created with BioRender.com.

Figure 2

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) Spike with Glycan Shield. SARS-CoV trimer (green, PDB: 6NB6) [20] displaying N-linked glycan distribution (blue spheres) and the predicted sites for potential O-linked glycosylation based on Net-O-Gly server 4.0 (red residues) [22].

Figure 3

Airborne Transmission of Respiratory Viruses. An infected donor can expel a range of aerosol sizes that can be virus-laden. These aerosols can fall onto surfaces to create fomites or be inhaled by a donor. At close range a recipient is exposed to all aerosol sizes, increasing infection probability. At a further distance away, recipients will inhale smaller aerosols. Created with BioRender.com