Some people who are infected with coronavirus do not get symptoms because their immune system is able to fight it off. Others may just have mild symptoms, such as fever, cough, and breathing difficulties. However, 5 to 15% of them die from the infection. That’s because the virus damages the victim’s respiratory system or spreads to the victim’s kidneys and sometimes into their brain. These severe cases can be fatal within one week of infection with severe pneumonia or septic shock. In severe cases, people may be admitted to ICU (intensive care unit) in hospital for their respiratory insufficiency and their kidney failure. Early death could occur even within one day of infection.
It is not yet known why some people are more severely affected by the disease than others. “There is a subset of people—about 10% of those infected—who will die quickly from this debilitating condition,” says Dr. Kirsty Bentley, the study’s lead author and assistant professor of pediatrics at Johns Hopkins University in Baltimore, Maryland. “And they have a much lower threshold for survival than those with milder disease. But the thing that we don’t know yet is why this subset of patients might die so quickly”.
The airborne nature of the virus is guilty
The virus is not transmitted through the air, like flu, but instead it spreads in droplets and tiny particles released by coughing or sneezing. The coronavirus is hard to detect in body fluids, because they are usually low enough to be undetectable. It lives on surfaces and in the air for several hours after a person has coughed or sneezed, but not long enough to infect someone else.
The new research shows the virus does not appear to damage a patient’s lungs immediately—in fact no one knows what exactly causes the damage that kills 5 to 15% of those infected. It may take weeks or months to become sick. The new research suggests that the damage may be caused by other viruses that spread through the blood and infiltrate tissues of the body.
The research also shows that people who do not recover from coronavirus die from a different cause “killing off” their immune system. “We found a new subgroup of patients with severely weakened immune systems,” said Bentley. “Senseless killing of their own immune cells causes them to develop severe lung infections.”
Bentley’s team has suggested for years that the virus is initially cleared from the lungs and then something else happens to make it lethal. In the new study, they found that patients with severe symptoms had high levels of immune system molecules called interferons, which are the body’s first line of defense against viral infections. They believe that interferons are the trigger for what is killing these patients. But interferons are generally good for you and so we do not know how this paradox is happening.
“We would like to be able to predict who will get severe disease or even death and then we can make interventions,” says Bentley. “If we can predict who is going to get the worst complications, then we can treat them in certain ways or perhaps give them some prophylaxis.”
Is there any connection with the blood of those infected?
We might be able to predict who is going to get the worst complications by looking at the interferons in their blood. It shows these high levels of interferons were not enough to control a person’s immune system from random and senseless killing of their own immune cells.
Lack of immune control may not be enough to kill someone, however. The researchers have also found that the virus attacks the liver, which is a fatal cause even in people with strong immune systems.
In addition to infection of the lungs by coughing and sneezing, some patients died from septic shock caused by the bacterium Staphylococcus aureus or from inflammation of the heart and blood vessels. The researchers discovered that the coronavirus makes these dangerous germs grow faster.
Researchers also found the patients who died suffered from five or more different viruses in their lungs, including influenza and rhinovirus. It is not known if these viruses contributed to their deaths, but it is likely they did. The researchers suspect that these infections make it harder for the body to fight off the coronavirus infection which on its own would not be fatal.
If you get infected with coronavirus, your symptoms will depend on how serious your immune system is weakened by interferon response and whether you have other infections such as flu or common cold virus rhinovirus, and Staphylococcus aureus bacterium.
“This is an important study that should be considered a wake-up call to the public,” says Bentley. “It seems clear that the coronaviruses are more deadly than we thought, and they can cause severe disease even in the absence of other infections. The goal should be to prevent people from getting sick in the first place.”
It is a constant threat to the environment
Coronavirus may not be yet here to kill you, but it is a constant threat. There are now ongoing outbreaks of human coronaviruses on every continent. And there are other animal coronaviruses too, which can infect pigs and cows, as well as other animals such as sheep and goats, causing severe illness or death in these livestock animals.
Coronavirus Research 1 in 149 people in the US are diagnosed with an acute coronavirus infection every year. Acute illness is a mild but often severe viral infection of the lung and causes around 5 to 15% of patients who get infected to develop severe complications.
Coronaviruses are not very well understood and the mechanism by which they cause disease is unclear. Diseases caused by these viruses tend to occur mainly in humans and animals, though some bat coronaviruses have been found in pigs as well as bats.
Coronaviruses are enveloped viruses that may be divided into three different groups according to the shape of their outer envelope: spherical, icosahedral, and oblate. The most important group of viruses is the so called HCoV-5/SARS Coronavirus. It was identified in 2003 by scientists from China and was subsequently found to cause severe disease in humans, but with a mortality rate less than 1%.