A contagion is clearly a complex phenomenon. The way that the COVID-19 pandemic has
affected different nations and the unique nature of the virus and its effects
on the human body make for a very puzzling problem. Added to this complexity is the fact that we are attempting to analyze and understand the contagion in real time with only limited historical data.
COVID-19 is clearly a dangerous contagion. The virus, SAR-CoV-2, is much more contagious
than the average flu and also appears to be about ten times as lethal.
The fact that SARS-CoV-2 can create rampant outbreaks and
huge challenges for healthcare systems with large numbers of resultant
fatalities has been made clear in Wuhan, Italy, Spain, France, the UK and the
U.S. However, the pandemic has not yet
had the devastating effect on developing nations that was expected, thankfully,
and has been contained in some countries with relative ease – Sweden for
example.
As we look forward to approaching summer in the U.S., there
are several factors that seem to be critical in determining how things will
develop from here:
Seasonality – Viruses are often seasonal. The flu virus, which is also a coronavirus,
has a distinct increase in its spread in winter and then more or less
disappears in summer. We do not know yet
whether a virus as contagious as SARS-CoV-2 will be ‘seasonal’, but the fact
that the contagion has seemed less dramatic in southern hemisphere countries
may indicate that it is. As far as I can
tell, no one is quite certain why viruses are seasonal. There may be many factors at play – the virus
may be less viable at warmer temperatures, the way people interact changes, the
air and atmosphere change, etc. It is
possible that summer will accelerate the decline of the contagion, which would
certainly be welcome news. But if that
happens, then we would definitely have to be wary of a fall and winter
resurgence.
Social Distancing Effect on Reproduction Number – Much
of the U.S. avoided skyrocketing contagion by putting in place very restrictive
social distancing measures, including the closing of restaurants, bars,
businesses, stores, schools and most events.
Additionally, many people are now wearing masks. Even with these measures, the reproduction
number is just under 1.0 in most states.
The big question is whether relaxing many of these restrictions will
cause the number to jump up (it has been estimated to be as high as 5.7 in some
situations). What is the ideal balance
of social distancing and ‘open for business’?
We will probably have to experiment to discover the right mix, and
hopefully we will not thrust ourselves right back into a catastrophic
situation.
Antibody Effects and Immunity – People who have had
COVID-19 have antibodies in their system.
Do these antibodies provide immunity to re-infection? If so, for how long? Will the immunity vary from person to
person? When a disease is rampaging in
real-time these are the types of questions that are so difficult to
answer. Large amounts of data need to be
gathered and analyzed to make any pronouncements. The goal of herd immunity, where enough of
the population has immunity to stop the spread of the disease (whether by
vaccination or having had the disease) is highly desirable but not easily
attained.
Health Risks of COVID-19 – The SARS-CoV-2 virus is
very dangerous to the elderly and those with serious health problems such as obesity,
diabetes, cardiovascular disease, high blood pressure, cancer and lung
disease. But it also occasionally
strikes young, healthy individuals with dramatic effect, putting them in ICU’s
on ventilators and sometimes killing them.
Yet, the virus can also be totally asymptomatic or have very minor symptoms,
especially in the very young. It takes
time to understand all of the health impacts that a virus can have, and we will
not understand all of the risks associated with allowing this virus to work its
way through the world population for months if not years. Another strange thing about this virus is
that the very young rarely show significant symptoms and there are very few
deaths in that age group, yet they are still a vector for transmission of the
disease.
Testing and Tracking – The general trend of thinking
in research groups and epidemiologists is that our only wise recourse in the
interim period before a vaccine is available is to lower the number of active
cases dramatically by continuing the strong restrictions that most countries
have put in place. Once the number of
active cases is low, then a policy of aggressive testing, tracking and quarantine
must be initiated to keep the contagion from re-surging. If such a system is in place, then a
reasonable level of ‘business as usual’ can be allowed.