COVID-19 in oncology settings

Abstract

As the world prepares for “brace for impact” against the rapidly spreading severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), patients with cancer pose a unique challenge for everyone including clinicians, public health experts, infection preventionists, and patients themselves. Immunocompromised hosts differ from the general population in many ways. First, they are themselves more vulnerable. Second, they harbor pathogens for a longer duration, making them more infectious. Third, it is difficult to keep them under quarantine because of their frequent medical needs. Lastly, the course of infection does not generally follow the natural history of the disease as seen in apparently immunocompetent hosts. Respiratory viruses are known to cause significant morbidity and mortality in patients with cancer and stem cell transplant recipients.[12] In immunocompromised adults with cancer, progression to pneumonia ranges from 30% to 50%, and for those who develop pneumonia, mortality can be as high as 75%.[3] Long-term complications associated with respiratory viral infections, such as airflow obstruction and bronchiolitis obliterans have developed in stem cell recipients.[4] These morbidity and mortality rates are significantly higher than those in the general population. Further, most of these respiratory viruses do not require specific antiviral therapy in the general population, but in immunocompromised hosts, these viruses require therapy with specific antiviral agents which are expensive and are of uncertain benefits.[2] While having few subtle differences, SARS-CoV-2 has behaved similarly to other respiratory viruses, and management of this virus is largely the same from both public health aspects and the clinician's point of view. The mean daily reproductive number (R0) for coronavirus disease 2019 (COVID-19) has varied from 2.35 to 1.05 depending on the time in the epidemic and the country in which it has been calculated. The median incubation period is estimated to be around 5 days, and a person remains infectious from day 2 (asymptomatic phase) to day 14.[567] While these numbers give a fair estimate about the dynamics of COVID-19, yet we need to keep in mind that these numbers have been obtained from the general population, and the viral dynamics may vary in immunocompromised hosts. For example, viral shedding in immunocompetent hosts for influenza is generally 7 days, whereas, the same period is around 19 days in immunosuppressed hosts.[8] These small changes in viral dynamics make management of respiratory infections among cancer patients more challenging as infection control practices are required for a longer duration of time. There is scarcity of data on the epidemiology and clinical features of SARS-CoV-2 among cancer patients, but as the virus spreads to a wider population, we will see more and more immunocompromised people acquiring the infection. In a study done by Liang et al., patients with cancer were observed to have a higher risk of severe events (a composite endpoint defined as the percentage of patients being admitted to the intensive care unit requiring invasive ventilation, or death) compared with patients without cancer (39% vs. 8%), and patients with cancer deteriorated more rapidly than those without cancer (median time to severe events, 13 days vs. 43 days).[9] Currently, good supportive care is the standard of care for COVID-19. Many drugs including lopinavir/ritonavir, ribavirin, hydroxychloroquine, darunavir/cobistat, and remdesivir are being evaluated. Vaccine development is also underway, but no vaccine is expected to be available for at least 12 months. The above remarks lead us to an old but effective saying, “Prevention is better than cure.” SARS-CoV-2 is mainly spread through droplet and contact routes. Procedures such as endotracheal intubation, bronchoscopy, and cardiopulmonary resuscitation may cause droplets to aerosolize. Hence, all centers taking care of immunocompromised hosts should have dedicated isolation rooms, appropriate personal protective equipment, adequately trained staff, and other measures in place well in advance. As most of the countries move from the containment phase to the delay and mitigation phase, it is prudent to have adequate healthcare infrastructure ready to avoid disastrous consequences of managing too many immunocompromised hosts infected with SARS-CoV-2 at the same time. Although there is not much evidence to support the postponement of elective surgeries and stem cell transplants in stable cancer patients, this strategy should be considered in areas where COVID-19 has community-level transmission, considering the higher rate of complications in this cohort. We, therefore, propose three strategies for patients with cancer in this COVID-19 crisis:first, an intensive education of cancer patients about infection control practices at the personal level; second, stronger emphasis on strict surveillance among patients with cancer; and third, development of good infection control practices in healthcare settings for taking care of cancer patients.