The coronavirus can be deadly for some people or no big deal for others. It can put a patient on a ventilator facing lonely death or can come and go without leaving a mark. The scientists across the globe are working day and night to find out what are the factors due which this virus affects people differently.

For our comprehensive coverage and latest updates on COVID-19 click here.

The issue of disease variability "is the most critical question about COVID-19," The Washington Post quoted Edward Behrens, chief of the rheumatology division at Children's Hospital of Philadelphia. "Why do some people get sick? Why do some people have no problem at all?" he said. However, National Institutes of Health Director Francis Collins on his blog has highlighted one potential breakthrough. He stated that the scientists developed an artificial intelligence tool that sorted the blood of COVID-19 patients and found 22 proteins that consistently appear among the patients who are severely ill.

The researchers have also found that COVID-19 victim who had Type A blood had a 50 percent higher risk of needing oxygen or a ventilator. Type O blood seemed to have a partial protective effect. Collins further stated in comparison to potential mutations and dosages, the most critical factor is the person getting infected -- the "host." Not everybody hosts the COVID-19 virus in the same way. "The most critical factor is the person getting infected -- the host," Collins stated.

Also, Jennifer Lighter, a hospital epidemiologist at NYU Langone found that obesity as one of the factors infecting people with COVID-19. COVID-19 patients with a body mass index between 30 and 34 -- obese under CDC definitions -- were two folds as likely to be admitted to the ICU than patients with a BMI under 30. Those with a BMI of 35 and over were three folds more likely to die than those with a healthy BMI. "As we are opening up the nation, one idea is to consider opening up by risk groups," Lighter stated while speaking to Wash Post.

On a closer look, in the U.K., there has been "virtually no excess death" for people under age 45 since the pandemic began, said Carl Heneghan, director of the Center for Evidence-Based Medicine at Oxford University. People who have little history of viral infections tend to have more severe reactions when they get infected later in life. "You have to try and stay healthy, get fit," Heneghan said. "If you've got diabetes, you've got to lose weight and moderate that. If you do all those things, your risk of dying is small, or very small."