COVID-19 Pathophysiology

Coronaviruses are a family of viruses that have existed for many years. These viruses cause illnesses such as the common cold, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

In December 2019, the coronavirus now known as COVID-19 emerged in Wuhang, China. This virus is highly contagious and its spread has been declared a pandemic. The estimate as of today (4/1/2020) is that the death toll in the United States may be anywhere from 100,000 to 240,000 Americans. So what is the pathophysiology of this virus?

Pathophysiology

The COVID-19 virus infects individuals through droplet transmission. It moves deeper into the body terminating in the spleen, intestines, or the lungs. The lungs are lined with epithelial cells and are infected by COVID-19 which then injects its genetic material into them. The cell executes the new COVID-19 instructions and duplicates the virus in healthy cells. After replicating, the cells self-destruct and then continue to spread the genetic message to keep replicating in healthy lung cells.

COVID-19 then attacks the immune system. It infects some immune system cells and causes them to overreact sending more immune cells to the lungs. Neutrophiles and killer T-cells start ordering healthy cells to start destroying themselves as well. In the majority of cases, the immune system figures out that the virus has hijacked the respiratory and immune system and begin to destroy the virus cells, leading to recovery.

In some situations, virus-infected individuals do not recover as quickly and develop pneumonia, possibly leading to mechanical ventilation and possible death. Those with a higher mortality rate include the elderly and immunocompromised.

Symptoms

Many of the symptoms of COVID-19, the seasonal flu, and allergies overlap. Symptoms of COVID-19 develop 2-14 days after exposure, most commonly occurring around day 4-5. Individuals that infected with COVID-19 have shown all of the following symptoms:

Fever
Cough
Shortness of breath

Other symptoms may include the following:

Tiredness
Sore throat
Achiness
Runny nose
Loss of smell
Anorexia

The diagnosis of COVID-19 is done by laboratory testing and can be confirmed within 4-6 hours using Real-Time Reverse Transcriptase (RT)-PCR Diagnostic Panels.

Transmission

COVID-19 is spread by droplet transmission. Someone is infected when they have virus-infected droplets touch their mucous membranes in their eyes, nose or mouth. This can happen directly by having someone cough, sneeze, or talk expelling the droplets or indirectly by touching a surface with the virus-infected droplets and then touching their eyes, nose or mouth.