Physiological vulnerabilities greatly impact the outcome of coronavirus disease 2019 (COVID-19) infection. The COVID-19 infection results in far more serious illness in patients with compromised physiological reserve (older patients, infants, and pregnant women) and in those with preexisting or poorly controlled comorbidities. The COVID-19 infection can be life-threatening in older patients with cancer, but there are no standard guidelines or individual hospital data regarding methods or policies implemented to guide clinicians. Evolving clinical experience suggests that cancer patients with COVID-19 have more serious complications, such as intensive care admission from severe pneumonia or sepsis and a greater case fatality rate. Cancer history portends the highest risk of serious events. Considering the evidence for a clear association for older age and higher levels of comorbidity with more severe COVID-19 symptoms and adverse outcomes, the concept of risk mitigation is highly relevant to older patients with cancer. Chronological age alone cannot be relied on to ascertain the true biological status of an individual, and a comprehensive geriatric assessment (CGA) provides a multidisciplinary diagnostic process that encompasses several objectively evaluable domains to reliably and objectively assess medical, psychosocial, and functional limitations. With formal assessment tools, previsit questionnaires and appropriate training can reduce this burden on the clinician performing the initial CGA. This would enhance overall capabilities in reliable use of recommendations regarding treatment for comorbidities, geriatric syndromes, supportive care, drug interactions, and toxicities. Routine use of CGA would mitigate most of the risks related to biological vulnerability. Measures to reduce hospital visits such as shorter radiotherapy fractionation and conversion of intravenous to oral systemic regimens can be considered. Proactive discussions regarding end-of-life and hospice care at isolation facilities should be discussed in the management of older patients with cancer and COVID-19 infection. Oncologists should make an extra effort to educate and provide additional guidance to help patients and caretakers making hard decisions regarding withholding anticancer treatment to mitigate the risk of viral infection.