Higher Viral Load Surprisingly Linked to Less Severe COVID-19 Cases
The significance of viral load has been discussed since the beginning of the COVID-19 pandemic. Pharmacists might be surprised to learn that, according to a new study, viral load actually is higher in non-hospitalized patients and is inversely correlated with duration of symptoms. Here is more information.
NEW YORK – It might stand to reason that a higher viral load would be correlated with greater disease severity and higher risk of hospitalization from an infectious agent. That is not the case, however, with the novel coronavirus.
A study in the American Journal of Pathology indicates that, with COVID-19, diagnostic viral load is “higher in non-hospitalized patients and has a significant inverse correlation with duration of symptoms. This inverse relationship of viral load and duration of symptoms was also observed in the hospitalized subgroup, assessed in a univariate and multivariate analysis.”
The NYU Langone Health-led research corroborates that viral loads peak shortly after symptom onset and support the results of initial Asian studies establishing that viral load peaks during the pre-symptomatic stage of the disease and slowly declines to become undetectable by day 18-21
“We believe that higher viral loads are seen in mild disease rather than severe disease as they reflect the time from onset of infection,” the authors write. “These findings are interesting when interpreted within our current knowledge of the natural history of COVID-19. While many COVID-19 patients recover from their initial symptoms over the course of 14-21 days, a sizeable proportion of patients show clinical deterioration to severe disease which usually occurs a week after symptom onset.”
Researchers say they embarked on the study because the dynamics of viral load of the 2019 novel coronavirus (SARS-CoV-2) and its association with different clinical parameters has remained poorly characterized in the United States patient population.
Using a cohort of 205 patients from a tertiary care center in New York City. the study team investigated associations between viral load and issues such as:
- severity of symptoms,
- disposition (admission vs direct discharge),
- length of hospitalization and admission to the intensive care unit,
- length of need for oxygen support and
- overall survival.
Results indicate that diagnostic viral load is significantly lower in hospitalized patients than in patients not hospitalized (log10 VL = 3.3 vs.4.0; p=0.018) after adjusting for age, sex, race, BMI, and comorbidities. Higher viral load also was associated with shorter duration of the symptoms in all patients and hospitalized patients only and shorter hospital stay (coefficient =-2.02,-2.61, -2.18; p<0.001, p=0.002, p=0.013, respectively).
“No significant association was noted between VL, admission to ICU, length of oxygen support, and overall survival,” the authors report. “Our findings suggest a higher shedding risk in less symptomatic patients; an important consideration for containment strategies in SARS-CoV-2. Furthermore, we identify a novel association between viral load and history of cancer. Larger studies are warranted to validate our findings.”