Hello, and welcome to Medicine with Dr. Moran. I'm Dr. Keith Moran. My viewers have asked me how the
current Coronavirus pandemic compares to other serious infectious outbreaks of coronaviruses
such as MERS and SARS This video is an update from a previous video that I made a number of
months ago on the same topic. I will talk about the different types of Coronaviruses and the
odds of dying from each one. Most people haven't heard about Coronaviruses before the last serious
outbreak in 2003 which was SARS but actually many of you have had coronavirus infections before.
There are seven main kind of Coronaviruses which can affect humans. They are listed on this slide.
Now the first four Coronaviruses produce common colds in adults. They're responsible for about
a third of upper respiratory tract infections during the winter and 5 to 10% of overall colds
in adults. These viruses are seasonal and they're identified between December and May
with a peak in January and February in the northern hemisphere. Only 2.5% of infections
are actually identified between June and September . Transmission for these common cold Coronaviruses
is through direct contact with infected secretions which are large aerosolized droplets.
Re-infection is common because immunity does tend to wane after you've had an infection. Now
there's no current treatment for coronavirus infections of these particular four types.
These common cold coronaviruses do not typically lead to death by themselves other than the fact
that they can set in motion secondary bacterial infections and other complications that might
lead to death in older people as well as people with other health problems.
This brings us to the three coronaviruses which cause significant disease in humans. The first is
MERS, the Middle Eastern Respiratory Syndrome and this was isolated in 2012 and is called MERS Cov.
It has been found primarily in the Arabian peninsula particularly South Arabia. The last
significant outbreak was in 2015. Cases though are still being reported globally all the time. Cases
have occurred worldwide secondary to travel in and out of the Arabian Peninsula. It's believed that
bats are likely the reservoir for this particular illness and that camels most likely serve as a
host. Camel to human interactions can transmit the virus and it's known that human to human
transmission can occur as you can see on this slide. The incubation period which is the time
from infection to the first symptoms is around five days with a range of two to fourteen days.
The symptoms are fever,, cough shortness of breath, myalgias, which means muscle aches and
GI symptoms in 20% of people. Acute respiratory distress syndrome when the lungs have been
overwhelmed with viral infection and secondary inflammation happens secondary to Pneumonia.
Now real-time PCR testing of lower respiratory tract specimens meaning sputum that you cough up
as opposed to upper respiratory tract specimens such as a swab that we might take from the nose
and throat is what's recommended here with MERS. This is because the virus tends to affect the
lower respiratory tract and there is much less infection noted in the upper respiratory tract.
Antibody tests are not available for this virus. There isn't a vaccine for MERS and there isn't any
specific treatment for MERS other than supportive care. The next virus I want to talk about is SARS.
This had a worldwide outbreak in 2003 where there were 8,096 cases reported.
Initial cases were noted in China and subsequently it spread to Hong Kong,
Vietnam, Singapore and Canada primarily as you can see from the slide. PCR testing of a swab from
the lower respiratory tract was what was used for diagnosis. The SARS virus much like MERS primarily
infects the cells of the lower respiratory tract. The current Coronavirus causing Covid-19 which is
called SARS Cov-2 tends to effect both the upper and lower respiratory tract and thus
is much more infectious or transmissible than both SARS and MERS. Now getting back to SARS
antibody testing can be done for SARS. The reservoir is likely to be bats or possibly Civets.
The spread was believed to be droplet but other forms of transmission were never ruled out.
This is a very similar illness with fever, malaise, headache, and muscle aches,
and then respiratory lung symptoms with lung failure ultimately.
Really the clinical presentation of MERS, SARS and Covid-19 are extremely similar. As far as
treatment goes for SARS there's no antiviral therapy, steroids are not recommended, and there's
no vaccine. Antibody plasma has not been utilized for this. Now surgical masks and N95 respirators
were studied and they were found to be useful at blocking the spread of SARS just like they're
helpful against Influenza like illnesses and other viral infections and even bacterial pneumonias.
The virus that's causing Covid-19 pandemic is of course SARS Covi-2. The virus is seen
on the slide. Unlike all of the coronaviruses it looks like a crown thus it's named a coronavirus.
This particular virus was first isolated in Wuhan, China. Covid-19 stands for Coronavirus Infectious
Disease 2019. It is believed to have come from an animal as it is very close similarity to bat
Coronaviruses but it also could have come from Pangolins. We really have not determined the
source of this virus. This is still something that requires further evaluation. If it does come from
an animal it would be a Zoonotic disease just like SARS and MERS as everyone knows
SARS-Cov-2 spreads through humans through close contact from respiratory droplets just like SARS
This slide shows the distinction between the case fatality rate and the infection fatality rate.
I frequently get questions about both of these terms.
The infection fatality rate is the percentage of people who die of all people who develop infection
with the Coronavirus and this of course is the statistic that my patients really want to know.
This of course is significantly less than the case fatality rate which is
the percentage of people who die out of all of the cases that come to medical attention.
Now going back to the case fatality rate slide the overall CFR for MERS is 34%
as of late September 2019 which is based on an average of a number of studies. Remember that
this is the case fatality rate and likely is a significant overestimate of the likelihood
of dying if you acquire the virus as there's no data on infection fatality rate. There has
not been widespread population testing to know what the chance is of dying if you get infected
because we simply don't know how many people have been infected with this particular Coronavirus
and either had minimal symptoms or no symptoms and so they've never come to medical attention.
Now based on a single study of 47 patients case fatality rates rose with increasing age from 39%
in the younger than 50 years of age group to 48% in those younger than 60 and 75% in people 60 or older.
Small studies and lack of widespread antibody testing prevents us from knowing the true
infection fatality rate. Comorbidities lead to a higher risk of fatal infection of course.
Now for SARS in 2003 there were 8,096 cases reported with 774 deaths and the case fatality
rate was 9.6% If you look at Covid-19 case fatality rates across the globe have been reported
in the 2 to 5% range but widespread testing for the virus with swabs or using antibody
tests have demonstrated that the infection is much more widespread than these numbers.
On this slide you can see the infection fatality rates for the three Coronavirus infections that
we're talking about. Remember again that infection fatality rates means that if you get the virus
how likely are you to die? Now they're in the 0.3 to at most 0.6% range for Covid-19.
Now the case fatality rate is currently estimated to be about 5 to 10 times what the infection
fatality rate is. The latest CDC data is on this particular slide.
Now their best estimate is in the last column and they express these risks as
ratios and not percentages. To go from a ratio to a percentage you have to multiply by one hundred.
As you can see the chance of death of course varies by age. I have summarized the CDC data on
the following slide. In people below the age of 19 the likelihood of dying if you acquire the virus
is less than 0.003%. In the 20 to 49 age group it's 0.02%.
In the 50 to 69 age group it's 0.5%. Lastly in the over 70 age group it's 5.4%.
Lastly if you take the IFR's for each age group and multiply them by the percentage
that age group comprises in the population in the U.S. then divide by four to figure out the average
and that comes out to 0.2%. That's the average overall IFR that the CDC
is now saying. In the U.K. their figures are a little higher on the order of 0.5%.
It's highly likely that the overall IFR is somewhere thus between 0.2 and 0.6%.
These numbers are low but they do not mean anything if you happen to be the person that gets
really sick with the virus and ends up in the ICU or perishes from this illness. Some people do get
long-term complications from Covid-19. Vaccines are now being rolled out starting with people in the
high risk groups. I have a video both on the Pfizer vaccine as well as the Moderna vaccine to give you
more information. These have both been authorized for emergency use in the UK, Canada and the U.S.
My videos answer all the questions that you may have in regards to these vaccines.
with any infection or disease being healthy is always the key to fighting it off successfully.
A good diet, regular physical exercise, good sleeping habits, and avoiding those bad habits such
as smoking or too much alcohol will go a long way to keep your immune system and body in great shape.
Supplements are important particularly vitamin D we know this from the pandemic. A multivitamin is
important as well making sure that you're getting enough Zinc and other nutrients are also important.
Thank you for joining me today on Medicine with Dr. Moran. Feel free to comment, go ahead
and share with your family and friends. Remember get healthy and stay healthy.