One of the most perplexing aspects of SARS-CoV-2 coronavirus infection has been the variable responses among those infected. Disease progression is unpredictable and ranges from asymptomatic, mild infection to life-threatening Acute Respiratory Distress Syndrome (ARDS). Mild infections are characterized by symptoms such as fever and cough, and are usually resolved spontaneously in a majority of the infected individuals. However, in severe cases, patients develop ARDS and acute lung injury with damage to alveolar lumen leading to inflammation and pneumonia, and resulting in Intensive Care Unit (ICU) admissions or even death. The cause of such differential outcomes is unknown though older age, presence of other disease comorbidities and the host immune response to the virus are believed to be some of the key factors in disease prognosis. Investigating the association of the host genome or transcriptome (the coding part of the genome that is responsible for making all the proteins in our cells) in individuals affected by COVID-19 can help understand and predict the degree of illness and guide clinical outcomes.
Genomic studies coupled with host transcriptome analyses can, thus, help to explain why people respond to COVID-19 in different ways. This will be crucial to identify and better protect those at greater risk of severe disease. As the pandemic proceeds, cases of reinfections (people who have already been infected earlier, recovered, and are then infected again), breakthrough infections (individuals who got infected after successful vaccination (15 days after two doses of vaccine), prolonged infections (patients who are positive for coronavirus much longer, up to several months) are rising and need to be examined in the context of the viral variant causing the infection as well the host response to it.