SARS-CoV-2 Variants Could Help in Predicting COVID-19 Patient Outcomes

Scientists who used genomic sequencing to track SARS-CoV-2 as it mutated have found that initial strains and subgroups of virus strains (called clades) were associated with higher mortality while newer variants were associated with lower hospitalizations and deaths.

These findings by a multidisciplinary team of scientists at Case Western Reserve University (Cleveland, OH) and Cleveland Clinic (Cleveland, OH) could also help guide future studies to analyze how the newer variants impact patient outcomes as the virus continues to evolve.


To better understand how the earlier mutations and clades altered clinical outcomes, the team of researchers analyzed the RNA sequences of data from 302 patients with COVID-19 during the first wave of the pandemic in Northeast Ohio. These clinical samples were obtained from Cleveland Clinic’s COVID-19 registry, a collection of data from nearly 50,000 patients who had been tested for the disease. By sequencing each specimen against the initial strain of the virus discovered in Wuhan, the research team identified 488 unique mutations, correlating with six virus strains (clades Wuhan, S, L, V, G, GH).

Results revealed that during the initial six weeks of the pandemic in Cleveland, the early virus strains were well established and contributed to higher incidents of death from the disease. However, within weeks these early virus strains were outpaced by more transmissible strains that were associated with lower hospitalizations and increased patient survival even when hospitalized. The greatest diversity of COVID-19 strains occurred in the first weeks before community strategies to limit viral spread were established. It is likely that state and federal responses may have prevented continued introduction of new variants from outside the community, and thereby decreased overall mortality.

“This study offers a detailed description of how the different COVID-19 clades evolved and competed once they were brought to Cleveland,” said Brian Rubin, chair of Cleveland Clinic’s Robert J. Tomsich Pathology and Laboratory Medicine Institute. “The linkage of viral clades to outcomes is quite important and highlights the importance of viral genome sequencing to gain a deeper understanding of new diseases.”

“These findings offer greater insight into how COVID-19 infections significantly outpaced the rates of COVID-19 hospitalizations and deaths as the pandemic progressed,” said Frank Esper, a pediatric infectious disease physician at Cleveland Clinic Children’s who led the research collaborative. “The research also helps to validate how viral clades can play an important role in predicting patient outcomes.”

Related Links:
Case Western Reserve University
Cleveland Clinic