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In International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases

BACKGROUND : The emergence of SARS-CoV-2 variants of concern has led to significant phenotypical changes in transmissibility, virulence, and public health measures. Our study used clinical data to compare characteristics between a Delta variant wave and a pre-Delta variant wave of hospitalized patients.

METHODS : This single-center retrospective study defined a wave as an increasing number of COVID-19 hospitalizations, which peaked and later decreased. Data from the United States Department of Health and Human Services was used to identify the waves' primary variant. Wave 1 (08/08/20-04/01/21) was characterized by heterogeneous variants, while Wave 2 (06/26/21-10/18/21) was predominantly Delta variant. Descriptive statistics, regression techniques, and machine learning approaches supported the comparisons between waves.

RESULTS : From the cohort(n=1318), Wave 2 patients(n=665) were more likely to be younger, have fewer comorbidities, require more ICU care, and show an inflammatory profile with higher C-reactive protein, lactate dehydrogenase, ferritin, fibrinogen, prothrombin time, activated thromboplastin time, and INR compared to Wave 1. The gradient boosting model showed an area under the ROC curve of 0.854(sensitivity 86.4%;specificity 61.5%;positive predictive value 73.8%; negative predictive value 78.3%).

CONCLUSIONS : Clinical and laboratory characteristics can be used to estimate the COVID-19 variant regardless of genomic testing availability. This finding has implications for variant-driven treatment protocols and further research.

Bhakta Shivang, Sanghavi Devang K, Johnson Patrick W, Kunze Katie L, Neville Matthew R, Wadei Hani M, Bosch Wendelyn, Carter Rickey E, Shah Sadia Z, Pollock Benjamin D, Oman Sven P, Speicher Leigh, Siegel Jason, Libertin Claudia R, Matson Mark W, Franco Pablo Moreno, Cowart Jennifer B


COVID-19, delta variant, genomics, machine learning, variants of concern