COVID 19 by the numbers — things to know

A compilation of info, as we know it, about this virus. Sources listed below.

R0 = 2-3
The “R-naught” is description of how spreadable a disease is; how virulent. For example, typical influenza has an R0 of just over 1, meaning that the disease spreads at a one-to-one rate. COVID 19’s R0 is between 2-3. This means that one person can spread it to 2-3 people; who then can spread it to 2-3 — effectively resulting in 9 people infected. This is the ‘exponential’ aspect of COVID that’s so different from other viruses.

6′ apart
We’re all aware that’s the distance we need to stand to create ‘social distancing.’ That’s because we distribute aerosols by breathing/speaking normally. There’s still clarity needed about how much viral load typical aerosols carry (and therefore the risk of exposure). We do know that droplets carry enough viral load to be a risk. Droplets exit the lungs with more vigorous breathing, such as singing, shouting, panting during heavy exercise, and certainly with coughing and sneezing. Covering our mouths becomes a simple strategy.

3 hours
The estimate of how long droplets stay in the air before landing on a surface. This measurement assumes still air flow and enclosed spaces. We don’t have clarity about how those factors may reduce the time line.

24 hours
General agreement of how long this relatively fragile virus can remain on surfaces (between hosts). By comparison, the super-hardy tuberculosis virus can last up to 6 months on surfaces as long as it’s not exposed to sunlight. (That’s why in early days of TB, people were gathered in treatment centers called ‘solariums.’)

2+ / 5 / 11.5 / 14 days
Incubation period between exposure and infection — realizing that some people show few or now symptoms. Two-plus days is a figure from very recent studies in China. Five days is the more agreed upon figure of median incubation period, meaning how long it takes for most people who get the disease. By eleven and a half days after exposure, most (99%) of the people who show symptoms have them. Fourteen days is the conservative, public health margin for all of us to keep to in case of exposure.

Day 1 = onset of symptoms
With the onset of symptoms, another clock begins. This one is important, because we’re learning that people are most infectious at the beginning of symptoms. While some pre-symptomatic contagion has been shown, later studies reveal that this pre-sypmtomatic window is less risky than first thought. What remains is that some people can be ‘silent spreaders’ — spreading the disease unknowingly — because their own symptoms are so mild. Why social distancing is a dance for all of us!

14 days
General span of time from infection to ‘shedding’ the virus — to being through the tunnel. People are developing antibodies — hooray! This is important for three reasons:
• There’s a high likelihood that people will have extended immunity, and so can come back into the work force, potentially in higher risk situations (volunteering, drivers, check out clerks, etc.), and
• Scientists are hot on the trail of vaccines, since this virus appears to be one that mutates slowly. We can be better prepared and protected the next time it comes around, and
• More immediately, clinicians are using antibodies donated from those who have shed the virus as a treatment: injecting antibody rich plasma into severely ill patients giving their immune systems a boost.

This situation keeps unfolding. Do want you need to do to take care of yourself, including the simple precautions of hand washing, social distancing, don’t touch your face. And all the things you know to do to take positive care: sleep, nutrition, exercise, heart connections with beauty and nature.

Ninja Nerd Science: These are great presentations!
Epidemiology, Pathogenesis, Diagnosis (50 min)
Treatment, Prognosis, Precautions (36 min)

CDC Website — COVID-19 pages

JAMA Network: weekly newsletter, articles, studies