Coronavirus disease 2019 (COVID-19) is an acute respiratory tract infection causing a pandemic
that emerged in 2019 initially in China involving 13.8% cases with severe, and 6.1% with critical
course and later throughout the globe. Vaccines or antiviral medications are yet to be used to prevent or
treat infections of Human Coronavirus (HCoV). The much-discovered HCoV found in 2003, SARSCOVID-
19, which caused respiratory syndrome, has special pathogenesis as it causes respiratory tract
infection. The coronavirus spike protein's association with its host cell receptor complement is crucial in
deciding the virus infectivity, tissue tropism and species variety. SARS, COVID-19, infects human cells
by binding to angiotensin-converting enzyme 2 (ACE2) receptor and uses the TMPRSS2 cell protease to
activate it. Lungs are most affected by COVID-19 as host cells are accessed by the virus through ACE2,
which is most abundant in alveolar cells of the lungs. Special attention and efforts should be given in
reducing transmission in vulnerable populations, including infants, health care providers and the elderly.
COVID 19, is the main causative agent of potentially lethal disease and is of significant concern for
global public health and in pandemics which was highlighted in this review.