The case of coronavirus disease (COVID-19) has become a global crisis. In addition, more variants of the virus have been discovered with easier transmission and more harmful effects. Thus, understanding the risk factors associated with the susceptibility and severity of COVID-19 is critical for disease control. This review article aims to describe the risk factors associated with the severity of COVID-19. This study uses the article review method from research results obtained through searching the journal sites Google Scholar, PubMed, ProQuest and ScientDirect in the 2020–2021 period. To find articles that match the inclusion criteria we used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) strategy. A total of nine studies met the inclusion criteria for this review. These nine studies were assessed for quality, data extraction and synthesis. Risk factors that contribute to the severity of COVID-19 are age, gender, chronic comorbidities, cardiovascular disease, diabetes, hypertension, kidney failure, cancer and a history of smoking. New findings, unvaccinated patients are at higher risk of severity. Risk factors associated with the severity of COVID-19 include a person’s individual characteristics, co-morbidities, smoking history and unvaccinated.