We are starting to understand the trajectory of spread of the coronavirus, and why it spreads so easily.
Firstly, the virus has a high Ro (pronounced “R naught”), which is a measure of how contagious it is. The
Ro for coronavirus is about 2.5, which means a person can easily transmit the virus to an average of 2.5
people. The Ro for the flu, by comparison, is only about 1.25, meaning it is about half that of
coronavirus. Therefore, you can see how coronavirus is 2x as contagious as the flu.
Secondly, the percent of the population that will contract coronavirus and be asymptomatic is 40%. This
means that 4 out of 10 people will not know they became infected and show no symptoms. An
asymptomatic individual may feel fine, but they are contagious and can easily transmit the virus to
unsuspecting others, who may become symptomatic. If you test an asymptomatic person, they will be
positive for about 3 days, then if you test them again, they will be negative. You can start to see the
limitations of testing asymptomatic individuals. The test detects active viral replication. If they test
negative, you still do not know if they had the virus and recovered, or if they were never infected at all.
This last point raises the question of testing reliability. While we should have rapid tests made available
to health care providers as early as next week, the more accurate and useful test is a test for antibodies.
When an individual has contracted the virus, he or she makes antibodies to it so that the next time that
individual comes in contact with the virus, their own body has the “memory” of it, and has the
antibodies to destroy it without the possibility of becoming sick. This antibody test, also called IgG and
IgM will take longer to roll out practically speaking, but will provide more useful and specific
information. The goal is to get this test within a month.
Thirdly, specific to Florida, 10% of the tests conducted statewide are positive. Based on this data,
epidemiologist extrapolate that 10% of the population is likely positive. If you account for testing bias,
that is, individuals who test tend to be more likely positive because they probably have some type of
symptom, then you can say the percentage of individuals in Florida who have the coronavirus is just
Putting all this information together, you can see how the combination of high infectivity plus an
asymptomatic carrier state can easily cause high spread of the virus. If someone is exposed to the virus,
it does not mean they will absolutely test positive or contract it. Our bodies have an “innate” immune
system which can neutralize many types of foreign bacteria and viruses, including coronavirus, and
eliminate them on the spot, thus preventing infectivity. There are numerous variables which cause
some people to become infected, while others will easily eliminate the foreign threat. The point is that
a person can be exposed to the virus, and not contract it.
This crisis is not just a healthcare crisis, but as I have said before, it is a worldwide crisis on many levels.
The most effective means at slowing the spread is to isolate from one another. While this is quite
difficult, this is the most important action that individuals can take. This action will save lives.
Understand that by staying home, you are contributing to the containment of the coronavirus. When
we go out in public, whether to the store to buy more food or essential items, we are putting ourselves
and others at risk of spreading the virus. Take a minute to decide if you absolutely must go to the store.
If it is not necessary, do not go. We have a great challenge in front of us, a challenge that may turn out
to be the defining moment of our lives. We have an opportunity to make a huge difference right now in
slowing the spread and flattening the curve, as I have said before. The ramifications are great. The
results will not be seen in the distant future, but in the immediate present, over the next few weeks.