New research finds COVID-19 can be spread through speech

Without a certified COVID-19 vaccine arriving anytime soon, flattening the disease’s exponential growth curve comes down to the mutualistic relationship between research and preemptive measures. As the number of confirmed cases increases so do the documented substrates that facilitate them. 

We know that SARS-Cov-2 fomites are small (with an average diameter of 0.1 micrometers).

We know  that they remain active for at least three hours while airborne and that this value increases to 72 hours (three days) when applied to plastic and stainless steel surfaces. On cardboard, the virus remains viable for up to 24 hours. On copper, it takes roughly four hours for the virus to become deactivated and infectious debris can live on smartphone screens, (assuming they’re composed of glass material) for up to 96 hours or just about four days. 

It was previously assumed that transmission most reliably occurs between an infected individual six feet or less away from a subject through infectious droplets produced by a sneeze or a cough.

The aforementioned distance turned out to be based on outdated information published more than 40 years ago. Ensuing literature determined that coronavirus-bearing droplets of all sizes can actually travel 23 to 27 feet from their host after emission.

Moreover merely speaking bears the potential to produce an alarming number of active aerosols from SARS-Cov-2 infected respiratory particles.

“Long ago it was established that ordinary breathing and speech both emit large quantities of aerosol particles. These expiratory particles are typically about 1 micron in diameter, and thus invisible to the naked eye; most people unfamiliar with aerosols are completely unaware that they exist,” researchers write in a new study published in the journal Aerosol Science and Technology. “The particles are sufficiently large, however, to carry viruses such as SARS-CoV-2, and they are also in the correct size range to be readily inhaled deep into the respiratory tract of a susceptible individual.”

The louder a carrier speaks the more infectious debris they emit while speaking. Superemmiters were defined as individuals who produce ten times as many fomites compared to the average infected individual. These findings welcome an extra degree of caution but mostly on the basis of assuming the worst. 

When it comes to the minutiae of incubation factors, contact-tracing performed by epidemiologists only tells us so much about risk. If an individual comes into contact with a confirmed carrier there are a myriad of ways in which contraction can occur. Although repository droplets pose the greatest threat, it’s not unknown how much of the virus needs to be present in an aerosol, turbulent gas cloud, or on a surface to cause infection. 

Different correlates like temperature, comorbidities and bio-dispositions further influence successful transmission and case severity. Some of the early patients who were infected by fomites located in the Wuhan Sea Market evidenced high viral loads and critical manifestations of COVID-19.

Conversely, some positive cases recorded in the US remain asymptomatic or exhibit mild symptoms irrespective of how they came into contact with active viral agents. 

“Although we argue here that speech plausibly serves as an important and under-recognized transmission mechanism for COVID-19, it is up to aerosol scientists to provide the technology and hard data to either corroborate or reject that hypothesis. In terms of technology, improved bioaerosol sampling technology (Pan et al. 2016) is necessary; the authors conclude.”The stakes for the world are enormous. The aerosol science community needs to step up and tackle the current challenge presented by COVID-19, and also help better prepare us for inevitable future pandemics.”

If you do not have access to a surgical mask, The CDC and Wake Forest University experts recommend constructing a mask composed of two layers of tightly woven 100% cotton fabric, a double layer of cotton with a thread count of at least 180, or a double layer of normal cotton with a layer of flannel in between. SARS-Cov-2 remains active on cotton for about 24 hours so be sure to disinfect with common household disinfectants and warm water after every use.