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Despite timely immunization programs, and efficacious vaccines conveying protection against SARS-CoV-2 infection, breakthrough infections in vaccinated individuals have been reported. The Delta variant of concern (VOC) outbreak in Guangzhou resulted in local transmission in vaccinated and non-vaccinated residents, providing a unique opportunity to study the protective effects of the inactivated vaccines in breakthrough infection. Here, we find that the 2-dose vaccinated group has similar peak viral titers and comparable speeds of viral RNA clearance to the non-vaccinated group but accelerated viral suppression in the middle course of the disease. We quantitatively demonstrate that peak viral pneumonia is significantly mitigated in the 2-dose vaccine group (median 0.298%) compared with the non-vaccinated (5.77%) and 1-dose vaccine (3.34%) groups. Pneumonia absorbance is approximately 6 days ahead in the 2-dose group (median 10 days) than in the non-vaccinated group (16 days) (p = 0.003). We also observe reduced cytokine inflammation and markedly undisturbed gene transcription profiles of peripheral blood mononuclear cells (PBMCs) in the 2-dose group. In short, our study demonstrates that prior vaccination substantially restrains pneumonia development, reduces cytokine storms, and facilitates clinical recovery.

Background Limited prior data suggest that preexisting liver disease is associated with adverse outcomes among patients with coronavirus disease 2019 (COVID-19). Fibrosis-4 (FIB-4) is a noninvasive index of readily available laboratory measurements that represents hepatic fibrosis. We evaluated the association between FIB-4 at the early stage of infection and COVID-19 outcomes. Methods FIB-4 was evaluated at admission in a cohort of 267 patients admitted with early-stage COVID-19 confirmed through reverse-transcription polymerase chain reaction assay. Hazard of ventilator use and of high-flow oxygen was estimated using Cox regression models controlled for covariates. Risks of progression to severe disease and of death/prolonged hospitalization were estimated using multivariable logistic regression models. Results Forty-one (15%) patients progressed to severe disease, 36 (14%) required high-flow oxygen support, 10 (4%) required mechanical ventilator support, and 1 died. FIB-4 between 1.45 and 3.25 was associated with a greater than 5-fold (95% confidence interval [CI], 1.2–28) increased hazard of high-flow oxygen use, a greater than 4-fold (95% CI, 1.5–14.6) increased odds of progression to severe disease, and an over 3-fold (95% CI, 1.4–7.7) increased odds of death or prolonged hospitalization. FIB-4 >3.25 was associated with a greater than 12-fold (95% CI, 2.3–68. 7) increased hazard of high-flow oxygen use and an over 11-fold (95% CI, 3.1–45) increased risk of progression to severe disease. All associations were independent of sex, number of comorbidities, and inflammatory markers (D-dimer, C-reactive protein). Conclusions FIB-4 at the early-stage of COVID-19 had an independent and dose-dependent association with adverse outcomes during hospitalization. FIB-4 provided significant prognostic value for estimating adverse outcomes among COVID-19 patients.

Approximately 15–20% of COVID-19 patients will develop severe pneumonia, and about 10% of these will die if not properly managed. Earlier discrimination of potentially severe patients basing on routine clinical and laboratory changes and commencement of prophylactical management will not only save lives but also mitigate the otherwise overwhelming healthcare burden. In this retrospective investigation, the clinical and laboratory features were collected from 125 COVID-19 patients who were classified into mild (93 cases) or severe (32 cases) groups according to their clinical outcomes after 3–7 days post-admission. The subsequent analysis with single-factor and multivariate logistic regression methods indicated that 17 factors on admission differed significantly between mild and severe groups but that only comorbidity with underlying diseases, increased respiratory rate (>24/min), elevated C-reactive protein (CRP >10 mg/L), and lactate dehydrogenase (LDH >250 U/L) were independently associated with the later disease development. Finally, we evaluated their prognostic values with receiver operating characteristic curve (ROC) analysis and found that the above four factors could not confidently predict the occurrence of severe pneumonia individually, though a combination of fast respiratory rate and elevated LDH significantly increased the predictive confidence (AUC = 0.944, sensitivity = 0.941, and specificity = 0.902). A combination consisting of three or four factors could further increase the prognostic value. Additionally, measurable serum viral RNA post-admission independently predicted the severe illness occurrence. In conclusion, a combination of general clinical characteristics and laboratory tests could provide a highly confident prognostic value for identifying potentially severe COVID-19 pneumonia patients.