Assessing changes in incubation period, serial interval, and generation time of SARS-CoV-2 variants of concern: a systematic review and meta-analysis.

BACKGROUND: After the first COVID-19 wave caused by the ancestral lineage, the pandemic has been fueled from the continuous emergence of new SARS-CoV-2 variants. Understanding key time-to-event periods for each emerging variant of concern is critical as it can provide insights into the future trajectory of the virus and help inform outbreak preparedness and response planning. Here, we aim to examine how the incubation period, serial interval, and generation time have changed from the ancestral SARS-CoV-2 lineage to different variants of concern. METHODS: We conducted a systematic review and meta-analysis that synthesized the estimates of incubation period, serial interval, and generation time (both realized and intrinsic) for the ancestral lineage, Alpha, Beta, and Omicron variants of SARS-CoV-2. RESULTS: Our study included 280 records obtained from 147 household studies, contact tracing studies, or studies where epidemiological links were known. With each emerging variant, we found a progressive shortening of each of the analyzed key time-to-event periods, although we did not find statistically significant differences between the Omicron subvariants. We found that Omicron BA.1 had the shortest pooled estimates for the incubation period (3.49 days, 95% CI: 3.13-4.86 days), Omicron BA.5 for the serial interval (2.37 days, 95% CI: 1.71-3.04 days), and Omicron BA.1 for the realized generation time (2.99 days, 95% CI: 2.48-3.49 days). Only one estimate for the intrinsic generation time was available for Omicron subvariants: 6.84 days (95% CrI: 5.72-8.60 days) for Omicron BA.1. The ancestral lineage had the highest pooled estimates for each investigated key time-to-event period. We also observed shorter pooled estimates for the serial interval compared to the incubation period across the virus lineages. When pooling the estimates across different virus lineages, we found considerable heterogeneities (I2 > 80%; I2 refers to the percentage of total variation across studies that is due to heterogeneity rather than chance), possibly resulting from heterogeneities between the different study populations (e.g., deployed interventions, social behavior, demographic characteristics). CONCLUSIONS: Our study supports the importance of conducting contact tracing and epidemiological investigations to monitor changes in SARS-CoV-2 transmission patterns. Our findings highlight a progressive shortening of the incubation period, serial interval, and generation time, which can lead to epidemics that spread faster, with larger peak incidence, and harder to control. We also consistently found a shorter serial interval than incubation period, suggesting that a key feature of SARS-CoV-2 is the potential for pre-symptomatic transmission. These observations are instrumental to plan for future COVID-19 waves.

Emergent TIPS for acute gastroesophageal variceal bleeding in cirrhotic patients with hepatocellular carcinoma.

OBJECTIVES: To estimate the safety and effectiveness of emergent transjugular intrahepatic portosystemic shunt (TIPS) creation for acute variceal bleeding (AVB) in cirrhotic patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Data of thirty-three patients with AVB and HCC undergoing emergent TIPS creation from January 2016 to January 2022 were enrolled and were retrospectively analyzed. The primary outcomes were the safety of emergent TIPS creation, the bleeding control rate, and the rebleeding rate. The secondary outcomes included overall survival (OS), liver function, overt hepatic encephalopathy (HE), and shunt dysfunction. RESULTS: Emergent TIPS creation was technically successful in 33 patients (100%) and one (3.0%) patient suffered a major procedure-related adverse event. The control rate of bleeding (within 5 days) was 100%. During a median follow-up period of 26.3 months, rebleeding occurred in 6 (18.2%) patients. The median OS was 20.0 months. The 6-week and 1-year survival rates were 87% and 65%, respectively. Laboratory tests showed no significant impairment of liver function following TIPS creation. The incidences of overt HE and shunt dysfunction were 24.2% and 6.1%, respectively. CONCLUSION: Emergent TIPS creation is feasible and effective for treatment of AVB in cirrhotic patients with HCC.

Counterfactual analysis of the 2023 Omicron XBB wave in China.

Background: China has experienced a COVID-19 wave caused by Omicron XBB variant starting in April 2023. Our aim is to conduct a retrospective analysis exploring the dynamics of the outbreak under counterfactual scenarios that combine the use of vaccines, antiviral drugs, and nonpharmaceutical interventions. Methods: We developed a mathematical model of XBB transmission in China, which has been calibrated using SARS-CoV-2 positive rates per week. Intrinsic age-specific infection-hospitalization risk, infection-ICU risk, and infection-fatality risk were used to estimate disease burdens, characterized as number of hospital admissions, ICU admissions, and deaths. Results: We estimated that in absence of behavioral change, the XBB outbreak in spring 2023 would have resulted in 0.86 billion infections (∼61% of the total population). Our counterfactual analysis shows that the synergetic effect of vaccination (70% vaccination coverage), antiviral treatment (20% receiving antiviral treatment), and moderate nonpharmaceutical interventions (20% isolation and L1 PHSMs) could reduce the number of deaths to levels close to seasonal influenza (1.17 vs. 0.65 per 10,000 individuals and 5.85 vs. 3.85 per 10,000 individuals aged 60+, respectively). The maximum peak prevalence of hospital and ICU admissions are estimated to be lower than the corresponding capacities (8.6 vs. 10.4 per 10,000 individuals and 1.2 vs. 2.1 per 10,000 individuals, respectively). Conclusion: Our findings suggest that the capacity of the Chinese healthcare system was adequate to face the Omicron XBB wave in spring 2023 but, at the same time, supports the importance of administering highly effective vaccine with long-lasting immune response, and the use of antiviral treatments.

Prognosis Prediction of CRAFITY Score in HCC Undergoing TACE Combined with PD-(L)1 Inhibitors and Molecular Targeted Therapy.

Background: The CRAFITY (C-reactive protein and alpha-fetoprotein in immunotherapy) score has demonstrated prognostic significance in hepatocellular carcinoma (HCC) patients undergoing immunotherapy. The study aimed to validate accuracy of CRAFITY score on predicting prognosis for patients with HCC treated with transarterial chemoembolization (TACE) combined with PD-(L)1 inhibitors and molecular targeted therapy. Methods: Eighty-five HCC patients who underwent TACE in combination with molecular targeted therapy (MTT) and PD-(L)1 Inhibitors were consecutively enrolled from November 2019 to November 2022. Patients were divided into CRAFITY 0 score (n=32), CRAFITY 1 score (n=31), and CRAFITY 2 score (n=22), respectively. The primary outcomes were overall survival (OS) and progression-free survival (PFS), and the secondary outcomes included tumor response rate and treatment-related adverse events (TRAEs). Factors affecting survival were identified via Cox regression analysis. Results: The median overall survival (OS) for HCC patients with CRAFITY scores of 0, 1, and 2 was 33.4 months (95% confidence interval [CI]: 27.1-39.7), 34.5 months (95% CI: 23.1-45.9), and 24.2 months (95% CI: 13.9-39.3), respectively, there were statistical differences among the three groups (p<0.05). The progression-free survival (PFS) was 14.1 months (95% CI: 10.0-18.2), 14.1 months (95% CI: 9.0-19.2), and 9.3 months (95% CI: 7.2-11.4) for patients with CRAFITY scores of 1, 2, and 3, respectively, with a significant difference between the three groups (p<0.05). In patients with CRAFITY scores of 1, 2, and 3, the disease control rates (DCR) were 94%, 84%, and 73%, respectively (p < 0.05), while the overall response rates (ORR) were 78.1%, 67.7%, and 59.1%, respectively (p = 0.318). A higher CRAFITY score showed a correlation with an increased frequency of fatigue and grade 3 fever (p<0.05). Moreover, CRAFITY 2 score was an independent risk factor for both OS (HR = 2.610(1.281-4.564), p = 0.014) and PFS (HR = 2.419(1.281-4.564), p = 0.006). Conclusion: The CRAFITY score may provide an efficient predictive capacity for prognosis in HCC patients undergoing TACE combined with PD-(L)1 inhibitors and molecular targeted therapy.