With the novel status of COVID-19, scientists and researchers are working day and night to understand everything possible about the coronavirus.
The general consensus among experts is that COVID-19 is spread by person-to-person contact and by coming into contact with contaminated objects and surfaces, according to the United States Centers for Disease Control.
Person-to-person contact involves respiratory droplets produced when an infected person coughs or sneezes. The droplets can land in the mouths or noses of people who are nearby, about 6 feet, or possibly be inhaled into the lungs, the CDC said.
While people are generally most contagious when they are showing symptoms, some spread might be possible before that; there have been reports of this occurring with COVID-19, but it is not thought to be the main way the virus spreads, according to health officials.
The way in which the virus actually attacks the body to make people sick is under investigation as well. The World Health Organization Scientific and Technical Advisory Group for Infectious Hazards found that COVID-19 replicates itself in the upper respiratory system of the human body, making droplets from coughing and sneezing an effective means of spreading the disease.
The CDC has found that infected people produce a large quantity of the virus at the beginning of the infection with an incubation period of about 5.1 days. The fact that symptoms do not appear immediately after infection means people can function normally and continue daily life as normal before even realizing they are sick.
Once infected, the body will launch an attack against the virus in which immune cells will target COVID-19, according to the CDC.
During this attack, people will likely feel symptoms of fever, tiredness and dry cough; medical experts say some people may develop a productive or “wet” cough, but it is less likely than a dry cough.
[MORE COVERAGE: Data shows these are the two most common coronavirus symptoms]
The World Health Organization reported COVID-19 attacks the lungs in three stages: viral replication, immune hyperreactivity, and pulmonary destruction. WHO also reported that not all people go through all stages of infection, and early findings suggest that about 82% of infections remain mild.
As described above, COVID-19 first enters the body, then starts replicating itself rapidly in the lungs, creating the viral replication stage.
The virus invades the cells of the lungs creating respiratory problems, ultimately filling the airways of patients with fluid and debris, according to WHO.
Phase two, immune hyperreactivity, occurs next, according to early studies on the progression of the disease. This is when the body’s immune system effectively kicks into overdrive and bombards the lungs with with immune cells in an effort to repair lung tissue. According to researchers at the University of Maryland School of Medicine, when this type of response is triggered, immune cells can overreact and damage healthy tissues. This can also make physical symptoms worse.
The third response phase, pulmonary destruction in which lung damage continues, then begins, much like the progression of the SARS disease, according to the WHO. In severe cases, respiratory failure can begin and patients may require the assistance of ventilators to breathe.
Older adults are at the greatest risk of dying if infected with coronavirus and of contracting COVID-19, many health experts have said. The data backs this up, too. A breakdown of all known cases and deaths by the Chinese Center for Disease Control and Prevention shows 14.8% of patients 80 years and older who were infected have died as a result. The mortality rate for younger patients in China was much lower.
Research and data also shows those with an underlying health condition are at higher risk for contracting the virus, including cardiovascular disease, diabetes, chronic respiratory diseases, hypertension and cancer, according to the report.