In 2018, a total of 2,839,205 resident deaths were registered in the
United States—25,702 more deaths than in 2017. From 2017 to 2018, the
age-adjusted death rate for the total population decreased 1.1%, and
life expectancy at birth increased 0.1 year. Age-specific death rates
between 2017 and 2018 decreased for age groups 15–24, 25–34, 45–54,
65–74, 75–84, and 85 and over.
Age-adjusted death rates decreased for six leading causes and
increased for two.
Life expectancy at birth increased 0.1 year from 78.6 years in 2017
to 78.7 in 2018, largely because of decreases in mortality from cancer,
unintentional injuries, chronic lower respiratory diseases, and heart
After increasing 0.2 year between 2010 and 2014, life expectancy
decreased 0.3 year between 2014 and 2017 (2).
The 0.1-year increase in the 2018 life expectancy estimate for the
total population results in the same estimate before the increase began
(78.7 in 2010), and is 0.2 year below the peak life expectancy of 78.9
In 2018, a total of 21,467 deaths occurred in children under 1 year,
which was 868 fewer infant
deaths than in 2017.
The IMR decreased for 2 (unintentional injuries and cord and
placental complications) of the 10
leading causes of infant death.
In 2018, the 10 leading causes of death (heart disease, cancer,
unintentional injuries, chronic lower respiratory diseases, stroke,
Alzheimer disease, diabetes, influenza and pneumonia, kidney disease,
and suicide) remained the same as in 2017.
Causes of death are ranked according to number of deaths (1). The 10
leading causes accounted for 73.8% of all deaths in the United States in
Severe Adult Respiratory Syndrome
CoronaVirus-2 (SARS CoV-2)
COronaVIrus Disease 2019 (COVID 2019)
Neal R. Chamberlain, Ph.D., Department of Microbiology/Immunology,
ATSU/Kirksville College of Osteopathic Medicine
SARS CoV-2 (old name 2019-nCoV)
is the viral cause
2019 or COVID-19. In December of 2019, SARS CoV-2 was identified as
the cause of an outbreak of acute respiratory illness in Wuhan,
China. As of March 19, 2020, there have been 229,336 cases of
COVID-19 reported worldwide with over 10,000 cases reported in the
SAR CoV-2 is a coronavirus (a positive sense single stranded RNA
virus) named because of the crown-like appearance of the
glycoprotein projections on the outer surface of the virus (see
image below). There are hundreds of coronaviruses. Most infect
animals (pigs, camels, bats and cats). Occasionally, these animal
coronaviruses can infect and cause disease in humans. This is called
a spillover event.
Seven different coronaviruses currently infect humans. Four cause
the common cold (229E, OC43, NL63 and HKU1). Three coronaviruses can
cause serious disease in humans; pneumonia, SARS (severe acute
respiratory syndrome), sepsis, septic shock and multiorgan
The first of the serious coronaviruses, SAR CoV-1 emerged in late
2002 and disappeared by 2004. MERS CoV (Middle East Respiratory
Syndrome) emerged in 2012 and remains in circulation in camels. The
third coronavirus of the serious three is SAR CoV-2 and it emerged
in December 2019 from China. Genome sequencing and phylogenic
analysis indicated that SAR CoV-2 is a betacoronavirus in the same
subgenus as SAR CoV-1 but in a different clade. SAR CoV-1 was a
spillover event from bats to humans.
Many believe SAR CoV-2’s reservoir host was also from bats.
However, differences between the bat coronavirus and SARS-CoV-2
suggest that an intermediate host infected humans. The intermediate
host that infected humans with SARS-CoV-2 is unknown. Phylogenetic
analysis of SARS-CoV-2 strains have identified two different types
of SARS-CoV-2 so far. They are designated type L (70 percent of the
strains) and type S (30 percent). The L type was most the most
common cause of human infection during the early days of the
epidemic in China. The S type accounts for most of the strains
outside Wuhan, China. The clinical implications of these findings
are currently unknown.
Incubation period- 14 days following exposure, with
most manifesting infection about four to five days after exposure
(median- 5.1 days).
Initial Presentation- The most common clinical
features at the onset of illness are fever (99%), fatigue (70%), dry
cough (59%), anorexia (40%), myalgias (35%), dyspnea (31%), and
sputum production (27%) (Notice runny nose does not appear to be a
common symptom. Rhinorrhea may indicate the patient has some other
cause, other than SAR CoV-2, for their respiratory symptoms). NO
clinical features can reliably distinguish COVID-19 from other viral
Pneumonia appears to be the most frequent serious manifestation
of infection. Symptoms include fever, cough, dyspnea, and bilateral
infiltrates on chest imaging (ground glass opacities with or without
consolidations in the periphery bilaterally on CT).
Presentations — Ranges from mild to critical. Most
infections are not severe.
- Asymptomatic- percent is unknown
- Mild- fever, dry cough and dyspnea TO mild
pneumonia - 81%
- Severe disease- dyspnea, hypoxia, or >50
percent lung involvement on imaging within 24 to 48 hours – 14%
- Critical disease- respiratory failure,
shock, or multiorgan dysfunction – 5%
Recovery- Appears to take around 2 weeks for mild
infections and 3-6 weeks for severe disease.
Age and severity of illness — All ages of patients
can acquire SARS-CoV-2. Adults of middle age and older are more
likely to have symptoms of this infection. The median age for
COVID-19 symptoms ranged from 49 to 56 years. In a report from
China, 87 percent of patients were between 30 and 79 years old. A
recent study in the US revealed that 38% of hospitalized patients
with COVID-19 were between 20 and 54 years of age.
Symptomatic infection in children is uncommon. If symptoms occur
in children, they are usually mild (low-grade fever, cough, sore
throat, OR focal pneumonia on CT; no oxygen supplementation needed).
Severe cases of COVID-19 have been reported in children. So far, all
children with severe disease have recovered.
Between 2-6.3% of symptomatic infections were in individuals
younger than 20 years old. Older age is also associated with a
higher percent with symptoms and increased mortality (see graph
below). The case fatality rate is around 8% for patients aged 70-79
and about 15% for patients 80 years or older.
Other predisposing conditions for severe disease-
Men have a higher fatality ratio than women. Patients with
cardiovascular disease, diabetes, respiratory disease, hypertension
and immunocompromised patients are more likely to manifest symptoms,
develop severe disease and to die following infection with SARS
CoV-2 (see graph below).
Complications- Some patients with mild symptoms
progress over the course of a week to severe disease. In patients
with pneumonia due to SARS CoV-2, dyspnea developed after 5-8 days
following onset of symptoms Hospital admission occurred after a
median of seven days of symptoms.
Acute respiratory distress syndrome (ARDS) is the most frequent
complication in patients with severe disease. ARDS developed in 20
percent after about eight days, and mechanical ventilation was
implemented in 12.3 percent. Age greater than 65 years, diabetes
mellitus, and hypertension were each associated with ARDS.
Other less frequent complications include arrhythmias (17%),
acute cardiac injury (7%) and shock (9%).
Overall case fatality rate is 1-3%. Fatality rate differs by
country and age of the patient. No deaths were reported among
COVID-19 has spread, in four months’ time from China to 164
countries (March 20, 2020). The only continent with no reported
cases is Antarctica. As of March 20, 2020, there have been 272,042
cases of COVID-19 reported worldwide with over 18,000 cases reported
in the US. States in the US with the highest number of reported
cases are New York, Washington, California, Florida, Massachusetts,
New Jersey, Illinois and Colorado.
Updated case counts can be found on the World
Health Organization and European
Centre for Disease Prevention and Control websites.
Transmission — Understanding of the transmission
risk is incomplete. Initially there was an association with people
who worked or visited a seafood market in Wuhan, China that sold
live animals. As the outbreak progressed, person-to-person spread
became the main mode of transmission.
Person-to-person spread of SARS-CoV-2 occurs by respiratory
droplets. Others have shown that the virus has a half-life survival
rate of 1.3 h on these airborne droplets. Virus is released in the
respiratory secretions when a person with infection coughs, sneezes,
or talks to another person. If those droplets make contact with the
mucous membranes (eye, nose, or mouth) a person can be infected.
Droplets typically do not travel more than six feet and do not
linger in the air; however, in one study, SARS-CoV-2 remained viable
in aerosols under experimental conditions for at least three hours.
Infection can also occur if a person touches an infected surface
and then touches their eyes, nose, or mouth. Preliminary research
indicates that the virus is viable on plastic and stainless steel
for up to three days, but does not survive on cardboard for more
than 24 h or on copper for more than 4 h.
The reported rates of transmission from an individual with
symptomatic infection vary by location and infection control
interventions. According to a joint WHO-China report, the rate of
secondary COVID-19 ranged from 1-5 percent in China. In the United
States, the symptomatic secondary attack rate was 0.45%.
Viral RNA levels appear to be higher soon after symptom onset
compared with later in the illness. Transmission might be more
likely in the earlier stage of infection. The R nought (Ro) varies
by study and has been calculated from 1.32 to 3.9.
Transmission of SARS-CoV-2 from asymptomatic individuals (or
individuals within the incubation period) has also been described.
However, the extent to which this occurs remains unknown.
SARS-CoV-2 RNA has been detected in blood and stool specimens.
Live virus has been cultured from stool in some cases but fecal-oral
transmission does not appear to be a significant factor in the
spread of infection.
SARS-CoV-2 has four structural proteins, known as the S (spike), E
(envelope), M (membrane), and N (nucleocapsid) proteins; the N
protein holds the RNA genome, and the S, E, and M proteins together
create the viral envelope. The spike protein allows the virus to
attach to the membrane of a host cell.
Like SAR CoV-1, SAR CoV-2’s S-protein binds to the host cell
receptor angiotensin converting enzyme 2 (ACE2). This host cell
receptor is present on epithelial cells of the conducting airways
(trachea, bronchi, bronchioles) and the alveoli (type 1 and 2
After a SARS-CoV-2 virion attaches to a target cell, the host
cell's transmembrane protease serine 2 (TMPRS2) cuts open the spike
protein, exposing a fusion peptide. The virion’s RNA is then
released into the cell. The host cell produces copies of the virus
that can then infect more cells. SARS-CoV-2 produces several
virulence factors that promote shedding of new virions and
inhibit host immune response.
Destruction of the host epithelial cells causes an immunological
response. This response brings in lymphocytes (T-cytotoxin cells;
CD8 cells) to destroy the virus infected cells. A number of
proinflammatory cytokines are also produced by the lymphocytes. One
of the proinflammatory cytokines, interleukin-1 (IL-1), can cause
the fever seen in many patients with this viral infection. The
immune response increases the amount of interstitial fluid in the
walls of the conducting airways and alveoli. On chest radiograph
this can be seen as an infiltrate.
At the same time the immune response results in partial filling
of the alveoli with fluid from the vasculature. This partial filling
results in the ground glass appearance of the lungs on CT. If the
immune response does not eliminate the infection at this stage then
the virus can gain access to the blood stream and be transported
This viremia can cause even more proinflammatory cytokines to be
produced. If high concentrations of these cytokines are produced it
can result in a cytokine storm resulting in septic shock and
Clinical suspicion and testing criteria- Since
there is no proven treatment or vaccine, initial management should
focus on early recognition of suspect cases, immediate isolation and
institution of infection control measures.
1. The possibility of COVID-19 infection should be considered in
patients with fever and/or respiratory tract symptoms (e.g., cough,
dyspnea) who have had any of the following in the prior 14 days:
- Close contact with a confirmed/suspected COVID-19 infected
person. This includes work in health care settings. Close
contact means being within six feet of a patient for a prolonged
period while not wearing personal protective equipment (PPE) or
having direct contact with infectious secretions while not
- Residence in or travel to areas where widespread community
transmission has been reported (e.g., China, South Korea, most
of Europe [including Italy], Iran, Japan).
- Potential exposure through attendance at events or spending
time in specific settings where COVID-19 cases have been
- The possibility of COVID-19 should also be considered in
patients with severe lower respiratory tract illness when an
alternative etiology cannot be identified, even if there has
been no clear exposure.
2. When COVID-19 is suspected, infection control measures should
be implemented and public health officials notified. Patients who do
not need emergent care should be encouraged to call prior to
presenting to a health care facility for evaluation. Many patients
can be evaluated regarding the need for testing over the phone.
The CDC notes that the decision to test for SARS-CoV-2 should be
based on clinical judgment. Most patients with confirmed COVID-19
have fever (subjective or confirmed) and/or symptoms of acute
respiratory illness (e.g., cough, dyspnea). 3. In areas where
testing capacity is limited, public health officials can guide
prioritization of testing. The CDC suggests prioritizing testing to
include hospitalized patients for infection control decisions,
symptomatic individuals who have a higher risk of poor outcomes
(e.g., age ≥65 years, chronic medical condition, immunocompromising
conditions), and those with high exposure risk (e.g., recent travel
to specific locations, contact with patients with COVID-19, or a
health care worker).
Patient sampling- Reverse Transcriptase
Polymerase chain reaction (RT-PCR) is the only test being used to
confirm cases of COVID-19 infection. Culture for the virus
is not recommended. RT-PCR should be performed as soon as possible
once a person has been prioritized for testing. The specimens used
for testing are taken from the respiratory tract according to the
patient’s clinical state:
- Nasopharyngeal swab (mild or asymptomatic suspected cases)
- Sputum (patients with productive cough, inducing sputum is
- Bronchial and tracheal secretions or bronchoalveolar lavage
(for patients receiving invasive mechanical ventilation)
Other laboratory tests- In patients with
COVID-19, the white blood cell count can vary. Leukopenia,
leukocytosis, and lymphopenia have all been reported. Lymphopenia
appears most common. Elevated lactate dehydrogenase and ferritin
levels are common, and elevated aminotransferase levels have also
been described. High D-dimer levels and more severe lymphopenia have
been associated with mortality.
Imaging findings — Chest CT in patients with
COVID-19 most commonly demonstrates ground-glass opacification with
or without consolidative abnormalities, consistent with viral
pneumonia. Chest CT abnormalities are more likely to be bilateral,
have a peripheral distribution, and involve the lower lobes.
Unenhanced CT images in a 33-year-old woman. A, Image shows
multiple ground-glass opacities in bilateral lungs. Ground-glass
opacities are seen in the posterior segment of right upper lobe and
apical posterior segment of left superior lobe. B, Image
obtained 3 days after follow-up shows progressive ground-glass
opacities in the posterior segment of right upper lobe and apical
posterior segment of left superior lobe. The bilateralism of the
peripheral lung opacities, without subpleural sparing, are common CT
findings of the COVID-19 pneumonia.
Therapy and Prevention
Supportive therapy- There are currently no proven
treatments for SARS CoV-2. A number are being tested and include
remdesivir, chloroquine, hydroxychloroquine, favipiravir, and
Mild disease; stay home, treat fever
(avoid ibuprofen to reduce fever since it suppresses the
immune system.), drink plenty of fluids, rest.
Severe disease; Hospitalize, supplemental oxygen,
ventilation depending on need.
Prevention includes social distancing and “DO THE FIVE”-
- Hands- wash them often.
- Elbow- cough into it.
- Face- don’t tough it.
- Feet- stay more than 3 ft apart.
- Feel- sick? Stay home.
Centers for Disease Control-
WHO SITUATION REPORTS-
EUROPEAN UNION UPDATES-
CDC Consumer information for coronavirus:
CDC Healthcare Professionals information for coronavirus:
CDC Clinics and healthcare facilities information for coronavirus:
COVID 19; Your Questions Answered:
Transmission of COVID 19-
Lecturio COVID 19 article-
Lecturio COVID-19 Video Course-
Interactive Covid 19 map:
Johns Hopkins COVID-19 Map-
Social distancing and prevention
Social distancing and self quarantine;
Wikipedia information on social distancing-
The best video explaining the math for social distancing (excellent
for people who don’t like the math)
How to hand wash with soap and water-
2020 Neal R.
Chamberlain, Ph.D., All rights reserved.