JAX President and CEO Edison T. Liu, M.D. Photo by Tiffany Laufer.
Social distancing means keeping people apart to minimize the chances of
catching COVID-19 and to reduce the chances of spreading the disease.
Implementing social distancing can be done at the individual level which is
focused on a person not catching COVID-19 or at a population level to slow
the spread of the pandemic across large groups of people.
You can get infected by inhaling the virus released by another person
coughing, or by touching the hands of an infected individual or surfaces
where the virus has been deposited. Social distancing at the level of the
individual is about washing hands before and after contact with other
people, going to the bathroom, preparing food, eating, and going to the
grocery store. Washing means using soap and not just a rinse. Hand
sanitizers are good, especially those with at least a 60% alcohol base, but
proper handwashing actually removes the virus from your hands while hand
sanitizer kills most of it—but not all of it.
This video from the CDC shows
how you should wash your hands.
If you should cough, do so into a napkin, discard that napkin and then wash
your hands or cough into the crook of your elbow to avoid contaminating
your hands. You should avoid all touching: handshakes, hugs, and social
kisses, and keep a distance of about 6 feet from the next person in public
places. Potentially contaminated surfaces such as door handles, shopping
cart handles, and tabletops should be cleaned prior to use. Though not
perfect, there is scientific evidence that guides these recommendations.
COVID-19 is primarily transmitted through tiny water droplets called
aerosols projected out by coughing. The distance that these droplets can
travel is up to 6 feet with each cough or sneeze. Experimentally, the virus
persists in these aerosols in enclosed spaces for up to three hours. The
viral dose coming from an infected individual depends on how much virus is
in their system. People with symptoms excrete more virus than those who
don’t. Since the virus does not survive outside the body well, the dose of
that aerosolized virus is reduced by half in about 1.2 hours.
If you are infected, standard surgical masks help by limiting the distance
that aerosols project; but these masks do little to prevent the intake of
infected particles. “N95” masks can filter much of the viral aerosols out,
but they require special fitting and are currently reserved to protect
healthcare workers so they are not generally available. Because of the
limitations of the supply of all masks, the recommendation is not to wear
one if you are healthy, but only if you have symptoms.
The virus when sprayed onto surfaces will survive for up to three days but
this varies according to the material of the surface: COVID-19 persists
longer on plastic and stainless steel than copper and cardboard. When the
information on all coronaviruses was reviewed, it was found that they
survive better in lower temperatures and higher humidity. Though there is
no cut-off of what specific temperature and humidity the virus survives
best, this justifies the closure of gyms with communal showers. The virus
on such surfaces can be effectively neutralized with solutions containing
70% or more alcohol, or solutions of 0.01% bleach, or 0.5% hydrogen
peroxide.
Often we are careful with social distancing and cleaning when we are not at
home but neglect the fact that our loved ones, including children, can
bring germs home. While social distancing does not mean social isolation,
surfaces should be cleaned at home, handwashing should continue, and family
members who are ill should not sleep in the same room with those who are
well.
At a community and population level, social distancing is accomplished
through limiting the formation of crowds or groups of people, and by
work-at-home and shelter-in-place policies. There is often confusion as to
why events like March Madness, the NCAA basketball tournament, should be
canceled since so few people relative to the population size are deemed
infected. Some are even indignant that events and social gatherings are
canceled. But the math tells us this must happen.
Proper social distancing means a shorter trajectory of the disease. China is
now reporting few, if any, new cases and beginning to lift some of the
quarantine guidelines. Ignoring CDC guidelines and continuing social
contact means a longer period of the epidemic and a higher infection and
death rate.
We now know there are asymptomatic carriers of COVID-19. Since there are
not enough tests for the infection, we do not know how many people are
infected but not showing symptoms. Joshua Weitz and his colleagues at
Georgia Tech calculated the chances of an infection spreading at the NCAA
basketball tournament. Even if only one infected individual attended March
Madness, many would become infected.
This is how the calculations go. Using the estimate that 20,000 Americans
out of the 330 million in our country are infected (as of March 20, there
are 15,219 confirmed US cases - a gross underestimate), they calculated
that every American has a 99.994% chance of being free of disease, or
16,500:1 chance to be in the clear. The probability that all 75,000 people
attending the tournament will be free of COVID-19 is only about 1%. That
means there is a 99% chance that the NCAA tournament will spark another
wave of infection as newly infected spectators return home.
For the COVID-19 pandemic, the danger is wherever people congregate in
significant numbers. This includes workplaces where people often spend 8
hours a day. This is why the Jackson Laboratory and other employers have
implemented a remote work policy to have workers whose jobs can be done
remotely, work from home. In this manner, all employees, including those who
perform essential functions on-site, will have the benefit of reduced
exposure to people traffic. The workplace is not inherently dangerous. It
all depends on how we manage the flow and the concentration of people.
So, what is the “safe” size of an event that makes it unlikely that an
infected individual will be present? That depends on how common the
COVID-19 infection is in the community. The currently recommended limit of
10 in a group means that you are willing to risk a 1% chance of inviting an
infected person, assuming the frequency of COVID-19 to be less than 200,000
in our population. Therefore, the more prevalent the disease in the
population, the smaller the group size limit.
Complicated? Yes, and the numbers are not only changing everyday but some
numbers, like how many Americans have been infected with COVID-19, are
still unknown. To get that number we need widespread testing, which will be
the topic of our next conversation.