Rebuild Public Trust with Good Information on Viral Loads

Said by Larry Leisure, Founder and Managing Partner at Chicago Pacific Founders:

Health authorities at all levels can regain public trust with specific real-life guidance.
For example, emphasize viral loads' role in indoor COVID-19 transmission. And discard often useless, 6-feet social distance edict.

MakeUsWell wants you to know that we deeply believe in and strive to be non-partisan in our work. But we also want you to get practical insights from the real world—our America, circa, December, 2020.

Governments and officials and politicians—of both parties—at the local, state, and federal levels have lost a lot of the public's trust. They need to communicate science clearly and credibly, And apply it intelligently to specific life situations. This will start the slow process of regaining the public's trust.

The six feet, physical distancing guideline—misnamed as social distancing—lost credibility. Because it's too vague, broad, and disconnected from sound scientific principles.

Some of the data here was based on Erin Bromage's work. But we augmented and refined that with our original research and data and insights.
Erin Bromage has a PhD in Microbiology and Immunology from James Cook University, Australia. He is an associate Professor of Biology at the University of Massachusetts, Dartmouth. He teaches and researches infectious diseases and host immune responses of animals.

The Fundamentals

People do these things.

Human Activity Droplets Simplified Characteristics
Breathing Nose or Mouth 50 - 5,000 Low velocity, fall to the ground
Speaking 200-250 per min Mix of high and low velocity particles
Loud Singing ~1,000 per min Most are higher velocity particles
Cough 3,000 Velocity ~50 mph
Most droplets are large, and fall quickly. But many stay in the air and can travel across an indoor space
Sneeze 30,000 Velocity ~200 mph
Most droplets are small and can travel across a room

Nota bene

We also analyzed more sophisticated medical studies and research. With particle mass emission rate, average # of droplets per frame and other metrics. We decided that you want the key insights distilled and the complexity removed.

The key insight is that droplets less than 5 microns in diameter, called aerosols, can remain in the air for hours.

We continue to build and augment these models and intend to present future simulations with more variables.

Viral Load?

The viral load is a metric that measures virus particles. Once a person has been infected, the viral load measures the amount of virus present. With COVID-19, the higher your viral load, the sicker you'll get.

An infected person can expel two hundred million virus particles. A successful Infection is the product of the 2 variables, Exposure to Virus and Time of exposure.

So let's say you talk to someone for 10 minutes, and they expel 225 droplets a minute, for a total of 2,250. This is much higher than the rule of thumb, ~1,000 particles to get infected. But this kind of behavior doesn't happen at stores with strangers.

Let's say you are walking around a large store like Costo. With general breathing—through the mouth or nose—about 50 viral particles per minute are released into the Costco.

(Again we simplify here, and don't account for the type of ventilation system, number of people in the store, the number of masks, filtration effectiveness of different types of masks, body of research, masks people wear, the current infection rate of that specific population, etc.)

But let's take an unlikely scenario—100% of the virus particles end up in your lungs. So you would need (1,000 / 50) or 20 minutes with the same person from less than 6 feet away to get infected.

In practice, mask compliance within stores tends to be ~90%+. And cashiers are often behind a glass barrier. So again the 6 feet guidance fails.

Effective Guidance

An effective public health guidance may be positioned as:

Don't be afraid to go closer than 6 feet from a person in a store. Just don't linger there. And stay silent and don't sneeze or cough.