One study postulates that the major genetic risk factor for severe COVID‑19 is inherited from Neanderthals.44 Researchers found that at least one copy of a Neanderthal-inherited haplotype on chromosome 3, known as the “risk haplotype,” occurs in about 50 percent of people in South Asia, compared to only 16 percent of Europeans. This risk haplotype significantly increases the likelihood of severe symptoms and hospitalization from COVID‑19.44 A haplotype is a set of DNA variations that tend to be inherited together.45 Another study stresses that genetic risk factors can make individuals susceptible to severe COVID‑19, and with that understanding these mechanisms underlying COVID‑19 can potentially pave the way to novel treatments for the disease.46

A comorbidity is the presence of one or more additional conditions often co-occurring with a primary condition.47 These conditions may increase risk of acquiring certain diseases or becoming more seriously ill from a disease, such as COVID‑19. Some conditions which may make an individual more susceptible to becoming extremely ill with COVID‑19, and possibly requiring hospitalization and more advanced medical treatment include: cancer, chronic lung or kidney disease, dementia, diabetes, Down syndrome, heart conditions, HIV infection, immunocompromised state, liver disease, obesity, pregnancy, cerebrovascular disease, and smoking or other substance use disorders (Table 1).47

Table 1.
Comorbid Condition Case Fatality Rate, %
Hypertension 6.0
Diabetes 7.3
Cardiovascular disease 10.5
Chronic respiratory disease 6.3
Cancer (any) 5.6
None 0.9