Coronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in
Wuhan, China in December 2019. The disease has since spread worldwide, leading to an
Symptoms of COVID-19 are variable, but often include fever, cough, headache, fatigue,
breathing difficulties, and loss of smell and taste. Symptoms may begin one to fourteen days after
exposure to the virus. At least a third of people who are infected do not develop noticeable symptoms.
Of those people who develop symptoms noticeable enough to be classed as patients, most (81%) develop
mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea,
hypoxia, or more than 50% lung involvement on imaging), and 5% suffer critical symptoms
(respiratory failure, shock, or multiorgan dysfunction). Older people are at a higher risk of
developing severe symptoms. Some people continue to experience a range of effects (long COVID) for
months after recovery, and damage to organs has been observed. Multi-year studies are underway
to further investigate the long-term effects of the disease.
COVID-19 transmits when people breathe in air contaminated by droplets and small
airborne particles containing the virus. The risk of breathing these in is highest when
people are in close proximity, but they can be inhaled over longer distances, particularly
indoors. Transmission can also occur if splashed or sprayed with contaminated fluids in
the eyes, nose or mouth, and, rarely, via contaminated surfaces. People remain contagious
for up to 20 days, and can spread the virus even if they do not develop symptoms.
Several testing methods have been developed to diagnose the disease. The standard
diagnostic method is by detection of the virus' nucleic acid by real-time reverse
transcription polymerase chain reaction (rRT-PCR), transcription-mediated amplification
(TMA), or by reverse transcription loop-mediated isothermal amplification (RT-LAMP) from
a nasopharyngeal swab.
Prevention And Treatment
Several COVID-19 vaccines have been approved and distributed in various countries,
which have initiated mass vaccination campaigns. Other preventive measures include
physical or social distancing, quarantining, ventilation of indoor spaces, covering
coughs and sneezes, hand washing, and keeping unwashed hands away from the face. The
use of face masks or coverings has been recommended in public settings to minimize the
risk of transmissions. While work is underway to develop drugs that inhibit the virus,
the primary treatment is symptomatic. Management involves the treatment of symptoms,
supportive care, isolation, and experimental measures.
John Hopkins University CSSE
Housed in the Johns Hopkins Department of Civil and Systems Engineering,
CSSE takes a multidisciplinary approach to modeling, understanding, and optimizing
systems of local, national, and global importance. These include medicine, health care
delivery, national infrastructure, information security, disaster response, and education.
In addition to faculty from across multiple engineering departments, CSSE utilizes the
expertise of researchers from the schools of Medicine, Public Health, Nursing, Arts and
Sciences, Business, and Education; and from JHU’s Applied Physics Laboratory, already
one of the nation’s leading centers of systems engineering.
Total cases refers to the number of confirmed infections of the COVID-19 virus
since the first known case was identified in Wuhan, China in December 2019.
Total deaths refers to incidents since December 2019 where COVID-19
was directly linked to causing acute complications, respiratory or otherwise, that
resulted in fatalities.
Total recovered refers to the number of cases in which individuals with confirmed COVID-19
virus cases were dismissed as being active or acute.
Mortality rate refers to the percentage of formely active COVID-19
virus cases that resulted in fatality or death.