ABSTRACT
Background: There have been no studies examining differences in clinical manifestations and prognosis between second and third generation coronavirus disease 2019 (COVID-19) patients. Our object was to analyze the epidemiological data and correlation between clinical types and COVID-19 generations. Methods: Older than 18 years COVID-19 patients who met two of the three items listed in COVID-19 Diagnosis Protocol were enrolled and divided into two groups based on epidemiological history. Clinical characteristics (age, gender, body mass index, course), disease severity, laboratory results (platelets, white blood cells, lymphocytes, inflammatory biomarkers, alanine aminotransferase, lactate dehydrogenase, creatine kinase, myoglobin, troponin, D-dimer blood biochemical indexes), clinical types were analyzed. Two groups were compared by chi-square test, group means were compared by t test, correlation between COVID-19 generations and clinical severity and clinical types were examined by Spearman correlation analysis. Results: There were no significant differences in gender composition (P=0.488), A-DROP scores (P=0.079) nor BMI (P=0.532) between the two generations. The number of second generation patients over 60 years was significantly greater than that in third generation (P<0.001). Creatine kinase levels of third generation patients were significantly higher than those of second generation patients at admission (P=0.009) and during hospitalization (P=0.023). The troponin levels of third generation patients were significantly higher than those of second generation patients at admission (P=0.020). At discharged, the creatine kinase and troponin levels were not significantly different between the two generations. Rate of severe (P=0.130) and critical cases (P=0.314) in second generation COVID-19 patients was not significantly different from that of third generation patients. Age (ρ=0.224, P<0.001), duration (ρ=0.317, P<0.001), transmission generation (ρ=0.269, P<0.001), serum creatine kinase (ρ=0.240, P<0.001), troponin (ρ=0.296, P<0.001), C-reaction protein (ρ=0.278, P<0.001), procalcitonin levels (ρ=0.221, P=0.001), lymphocyte count (ρ=-0.245, P<0.001), and platelet count (ρ=-0.265, P<0.001) of COVID-19 patients were significantly s correlated with clinical types. Conclusions: Increased virulence may occur in specific tissues and organs during intergenerational transmission of COVID-19 virus. COVID-19 virus virulence in different regions is different. The clinical prognosis of COVID-19 patients is closely related to age, course, transmission generations, and some laboratory indicators. Transmission generation, regional differences, and laboratory indicators may have certain potential value in predicting prognosis and treatment.
ABSTRACT
One of the key epidemiological characteristics that shape the transmission of coronavirus disease 2019 (COVID-19) is the serial interval (SI). Although SI is commonly considered following a probability distribution at a population scale, recent studies reported a slight shrinkage (or contraction) of the mean of effective SI across transmission generations or over time. Here, we develop a likelihood-based statistical inference framework with truncation to explore the change in SI across transmission generations after adjusting the impacts of case isolation. The COVID-19 contact tracing surveillance data in Hong Kong are used for exemplification. We find that for COVID-19, the mean of individual SI is likely to shrink with a factor at 0.72 per generation (95%CI: 0.54, 0.96) as the transmission generation increases, where a threshold may exist as the lower boundary of this shrinking process. We speculate that one of the probable explanations for the shrinkage in SI might be an outcome due to the competition among multiple candidate infectors within the same case cluster. Thus, the nonpharmaceutical interventive strategies are crucially important to block the transmission chains, and mitigate the COVID-19 epidemic.