It is known that old age, persons with chronic conditions including immunosuppression, diabetes, heart disease, chronic lung disease, kidney failure, dialysis and cancer are at higher risk for severe illness and or death from COVID-19 infection. That said, we have seen a few lucky ones in the practice with several underlying conditions, SARS-CoV-2 PCR positive bilateral pneumonia, insist on going home. In these few instances the patients acted against medical advice, refusing to return to the hospital to be admitted. Such dissent has been uncommon in my experience throughout the pandemic. Our algorithm is "...best to assume anyone with any of these conditions will likely do poorly, so monitor closely". Beyond the current generalizations it remains quite confounding in our encounter with patients to predict who with underlying condition(s) will do well. The algorithm is much less useful, from an ambulatory care doctor's perspective, than if one could tell who will do well. And the art of solving for who in my primary care practice might do poorly after testing positive is not helped when an otherwise healthy 19 year old member ends up having ECMO to survive the infection. These all point to the fact that there's a lot more to COVID-19. A recent published retrospective study of nearly 680 patients showed that the viral load (calculated by the Ct value from the initial nasopharyngeal swab test) at presentation is a reliable predictor of the risk for mechanical ventilator support and in-hospital death. The Ct (cycle threshold) is a value ascribed by the assay to the number of viral replication cycles that correlates inversely with quantitative viral load. It is not routinely reported or released to clinicians. The researchers grouped patients in the study into 3 , low (Ct>30) , medium (Ct 25-30) and high (Ct <25) viral loads.
35% of patients with a high viral load were more likely to die in-hospital. While 17.6% of those with a medium viral load died in-hospital only 6.2% with a low viral load died in-hospital. The risk of intubation was also higher in patients with a high viral load (29.1%), compared with those with a medium (20.8%) or low viral load (14.9%). Patients with higher viral loads were more likely to develop myocardial infarction, congestive heart failure, and acute kidney injury requiring hemodialysis.
Using initial viral load assessment, providers may have an added tool to triage patients. Identifying, as early as the time of the initial COVID-19 PCR test results, those who are likely to need more intensive monitoring is one step ahead of this disease. In addition, identifying these group of patients early will aid decisions in allocating scarce resources such as remdesivir treatment. Admittedly, this tool seems most suited and applicable to guiding in-hospital patient care, but that may change.
Furthermore, additional viral load studies may begin to answer other questions such as the probability that very high viral load may in of itself be equivalent to all the other risks combined. High enough to explain the unexpected disease severity in young persons without any comorbities.
https://academic.oup.com/cid/article/doi/10.1093/cid/ciaa851/5865363