Comprehensive humoral and cellular immune responses to SARS-CoV-2 variants in diverse Chinese populations: A benefit perspective of national vaccination (preprint)

The emerging SARS-CoV-2 variants have made great challenges to current vaccine and pandemic control strategies. B.1.1.529 (Omicron), which was classified as a variant of concern (VOC) by the World Health Organization on November 26th, 2021, has quickly become the dominant circulating variant and causing waves of infections. It is urgent to understand the current immune status of the general population given that pre-existing immunity has been established by national vaccination or exposure to past variants. Using sera from 85 individuals (including 21 convalescents of natural infection, 15 cases suffered a breakthrough infection after vaccination, and 49 vaccinated participants without infection history), we showed that the cross-neutralizing activity against VOCs such as Omicron can be detected in 53 (62.4%) cases, although less potent than against the Wuhan-1 strain (WT), with a 3.9-fold reduction in geometric mean neutralizing titer (GMT) (130.7, 95% CI 88.4-193.3 vs 506, 355.8-719.7, respectively). Subgroup analysis revealed significantly enhanced neutralizing activity against WT and VOCs in Delta convalescent sera. The neutralizing antibodies against Omicron were detectable in 75% of convalescents and 44.9% of healthy donors (p = 0.006), with a GMT of 289.5, 180.9-463.3 and 42.6, 31.3-59, respectively. However, the protective effect against VOCs was weaker in young convalescents (aged < 18y), with a detectable rate of 50% and a GMT of 46.4 against Omicron, similar to vaccinees. The pan-sarbecovirus neutralizing activities were not observed in vaccinated SARS-CoV-1 survivors. A booster dose significantly increased the breadth and magnitude of neutralization against WT and VOCs to different degrees than full vaccination. In addition, we showed that COVID-19 inactivated vaccines can elicit Omicron-specific T cell responses. The positive rates of ELISpot reactions were 26.7% (4/15) and 43.8% (7/16) in the full vaccination group and the booster vaccination group, respectively. The neutralizing antibody titers declined while T-cell responses remain robust over 6 months. These findings will inform the optimization of public health vaccination and intervention strategies to protect diverse populations against SARS-CoV-2 variants.

Effectiveness of Convalescent Plasma for Treatment of COVID-19 Patients (preprint)

Background and objective: The outbreak of COVID-19 has become a global health concern. In this study, we evaluate the effectiveness and safety of convalescent plasma therapy in patients with severe and critically ill COVID-19. Methods: Sixteen COVID-19 patients received transfusion of anti-COVID-19 antibody-positive convalescent plasma. The main outcome was time for viral nucleic acid amplification (NAA) test turning negative. Clinical laboratory parameters were measured at the baseline (d0) before plasma transfusion, and day 1 (d1), day 3 (d3) after transfusion as well. Results: Among the 16 patients, 10 of them had a consistently positive result of viral NAA test before convalescent plasma transfusion. Eight patients (8/10) became negative from day 2 to day 8 after transfusion. Severe patients showed a shorter time for NAA test turning negative after transfusion (mean rank 2.17 vs 5.90, P = 0.036). Two critically ill patients transfused plasma with lower antibody level remained a positive result of NAA test. CRP level demonstrated a decline 1 day after convalescent plasma treatment, compared with the baseline (P = 0.017). No adverse events were observed during convalescent plasma transfusion. Conclusions: Viral NAA test of most patients with COVID-19 who received convalescent plasma transfusion turned negative on the 2nd to 8th days after transfusion, and the negative time of severe patients was shorter than that of critically ill patients.

Clinical characteristics and epidemiology survey of lung transplantation recipients accepting surgeries during the COVID-19 pandemic:from area near Hubei Province (preprint)

Lung transplantation recipients (LTx) were susceptible to severe acute respiratory syndrome-corona virus-2 (SARS-Cov-2) and suffered a higher mortality risk than healthy subjects. Here we aim to analyze whether it was appropriate or and valuable to maintain lung transplant programs in medical institutions accepting coronavirus disease 2019 (COVID-19) patients. In this study, the clinical characteristics, laboratory testing and epidemiology survey results of 10 LTx recipients undergoing allograft lung transplantation surgeries in the First Affiliated Hospital of Zhengzhou University during the COVID-19 pandemic were collected. A web-based epidemiology questionnaire was used to collect the information of LTx recipients after discharge. Up to now, none of the LTx recipients or their family members get infected with SARS-CoV-2 during the novel coronavirus pandemic. In conclusion, under the premise of taking appropriate preventive measures during hospitalization and after discharge, the lung transplant program can be maintained in the medical institution that accepts patients with COVID-19.