Effectiveness of SARS-CoV-2-inactivated vaccine and the correlation to neutralizing antibodies: A test-negative case-control study.

Severe acute respiratory syndrome coronavirus 2 breakthrough infection in highly vaccinated populations raises study on the effectiveness for inactivated vaccine, including effectiveness of the vaccine dose, the continuance of effectiveness, the effectiveness against severe/critical coronavirus disease 2019 and against secondary attacks. A population of 10 870 close contacts were investigated in a Delta variant's epidemic. The effectiveness of vaccination was estimated in a test-negative case-control study. In addition, serum was used to detect neutralizing antibodies, to explore their correlation to effectiveness. The vaccine effectiveness (VE) values were estimated for populations aged 12 years or older. The overall adjusted VE was 56.2% and a two-dose vaccine was more effective than a one-dose vaccine (56.7% vs. 43.8%). In addition, the population that got the second dose vaccine within 2 months showed higher VE than the population vaccinated for longer than 2 months (61.5% vs. 52.3%). Among the population who vaccinated 2 doses or within 2 months, a higher level of neutralizing antibodies was observed. For infected cases, vaccinated populations showed lower rates of transmission (2.63% vs. 4.36%). Further, those vaccinated cases, who were not found causing transmission, had a higher level of antibodies. The study provided a full view of the effectiveness of inactivated vaccines in a real-world setting. The time-related VE against infection and lower transmission of breakthrough vaccinated cases were observed, which may indicate that a necessity of a booster vaccine to maintain the effectiveness and high level of neutralizing antibody.

Evaluating the value of anti-SARS-CoV-2 antibody detection and neutralizing responses with euvirus: A population of 10776 close contacts in the epidemic of Fujian.

BACKGROUND: Nucleic acid detection represents limitations due to its false-negative rate and technical complexity in the COVID-19 pandemic. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests are widely spread all over the world presently. However, there is no report on the effectiveness of anti-SARS-CoV-2 antibody testing methods in China. METHODS: We gathered 10776 serum samples from close contacts of the SARS-CoV-2 infections in Fujian of China and used 2 chemiluminescence immunoassays (Wantai Bio., Yahuilong Bio.) and 2 lateral flow immunoassays (Lizhu Bio. and Dongfang Bio.) to perform the anti-SARS-CoV-2 antibody tests in China. RESULTS: The 4 antibody tests have great diagnostic value for infected or uninfected, especially in the neutralizing antibodies tests, the AUC can reach 0.939 (Wantai Bio.) and 0.916 (Yahuilong Bio.). Furthermore, we used pseudoviruses and euvirus neutralization assay to validate the effectiveness of these antibody test, the results of pseudoviruses neutralization assay or euvirus neutralization assay shows a considerable correlation with the 4 antibody detection respectively, particularly in euvirus neutralization assay, neutralizing antibodies detected by Wantai Bio. or Yahuilong Bio., the correlation can get the level of 0.93 or 0.82. CONCLUSIONS: The findings of this study demonstrate that the detections of antibodies have profound value in the diagnosis of COVID-19.

Unvaccinated Children Are an Important Link in the Transmission of SARS-CoV-2 Delta Variant (B1.617.2): Comparative Clinical Evidence From a Recent Community Surge.

Objective: To evaluate the necessity of Covid-19 vaccination in children aged < 12 y by comparing the clinical characteristics between unvaccinated children aged < 12 y and vaccinated patients aged ≥ 12y during the Delta surge (B.1.617.2) in Putian, Fujian, China. Methods: A total of 226 patients with SARS-Cov-2 Delta variant (B.1.167.2; confirmed by Real-time PCR positivity and sequencing) were enrolled from Sep 10th to Oct 20th, 2021, including 77 unvaccinated children (aged < 12y) and 149 people aged ≥ 12y, mostly vaccinated. The transmission route was explored and the clinical data of two groups were compared; The effect factors for the time of the nucleic acid negativization (NAN) were examined by R statistical analysis. Results: The Delta surge in Putian spread from children in schools to factories, mostly through family contact. Compared with those aged ≥ 12y, patients aged < 12y accounted for 34.07% of the total and showed milder fever, less cough and fatigue; they reported higher peripheral blood lymphocyte counts [1.84 (1.32, 2.71)×10^9/L vs. 1.31 (0.94, 1.85)×10^9/L; p<0.05), higher normal CRP rate (92.21% vs. 57.72%), lower IL-6 levels [5.28 (3.31, 8.13) vs. 9.10 (4.37, 15.14); p<0.05]. Upon admission, their COVID19 antibodies (IgM and IgG) and IgG in convalescence were lower [0.13 (0.00, 0.09) vs. 0.12 (0.03, 0.41), p<0.05; 0.02 (0.00, 0.14) vs. 1.94 (0.54, 6.40), p<0.05; 5.46 (2.41, 9.26) vs. 73.63 (54.63, 86.55), p<0.05, respectively], but longer NAN time (18 days vs. 16 days, p=0.13). Conclusion: Unvaccinated children may be an important link in the transmission of SARS-CoV-2 delta variant (B1.617.2), which indicated an urgent need of vaccination for this particular population.

Unvaccinated Children Are an Important Link in the Transmission of SARS-CoV-2 Delta Variant (B1.617.2): Comparative Clinical Evidence From a Recent Community Surge

Objective To evaluate the necessity of Covid-19 vaccination in children aged < 12 y by comparing the clinical characteristics between unvaccinated children aged < 12 y and vaccinated patients aged ≥ 12y during the Delta surge (B.1.617.2) in Putian, Fujian, China. Methods A total of 226 patients with SARS-Cov-2 Delta variant (B.1.167.2;confirmed by Real-time PCR positivity and sequencing) were enrolled from Sep 10th to Oct 20th, 2021, including 77 unvaccinated children (aged < 12y) and 149 people aged ≥ 12y, mostly vaccinated. The transmission route was explored and the clinical data of two groups were compared;The effect factors for the time of the nucleic acid negativization (NAN) were examined by R statistical analysis. Results The Delta surge in Putian spread from children in schools to factories, mostly through family contact. Compared with those aged ≥ 12y, patients aged < 12y accounted for 34.07% of the total and showed milder fever, less cough and fatigue;they reported higher peripheral blood lymphocyte counts [1.84 (1.32, 2.71)×10

Correlation between chest CT severity score and laboratory indicators in patients with Coronavirus disease 2019 (COVID-19).

OBJECTIVE: The association between computed tomography (CT) and clinical severity of COVID-19 has been demonstrated. However, there are few studies on CT and laboratory indicators in patients in COVID-19. Our aim was to explore the correlation between chest CT images and laboratory indicators of patients with COVID-19 pneumonia. METHODS: This was a retrospective study of patients with COVID-19 diagnosed and treated at the Affiliated Hospital of Putian University from 24 January 2020 to 6 March 2020. The correlation test between first chest CT score and blood cell analysis, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), blood biochemistry and T lymphocyte subsets (T-Ls) was investigated. RESULTS: Among the 56 patients, there were 36 (64.3%) males and 20 (35.7%) females. The mean age of the patients was 46.54 ± 15.82 (range, 15-86) years. The CT score in the moderate group was higher than in the mild group (5.06 ± 0.77 vs 1.87 ± 0.88, P < .05), and higher in the severe group than in the moderate and mild groups (10.71 ± 4.21, P < .05). In addition, the ESR was significantly higher in the severe group than mild group (32.00 (26.04, 58.24) vs 11.00 (7.84, 24.70) mm/h, P < .05). The CD3, CD4, CD8 and CD4/CD8 cells were not different (all P > .05). The CT scores of all patients correlated positively with CRP, LDH and ESR (all P < .01). CONCLUSION: The chest CT characteristics of patients with COVID-19 correlated positively with CRP, ESR and LDH, which may use one of the indicators for the assessment of disease severity.

Diverse immunoglobulin gene usage and convergent epitope targeting in neutralizing antibody responses to SARS-CoV-2.

It is unclear whether individuals with enormous diversity in B cell receptor repertoires are consistently able to mount effective antibody responses against SARS-CoV-2. We analyzed antibody responses in a cohort of 55 convalescent patients and isolated 54 potent neutralizing monoclonal antibodies (mAbs). While most of the mAbs target the angiotensin-converting enzyme 2 (ACE2) binding surface on the receptor binding domain (RBD) of SARS-CoV-2 spike protein, mAb 47D1 binds only to one side of the receptor binding surface on the RBD. Neutralization by 47D1 is achieved independent of interfering RBD-ACE2 binding. A crystal structure of the mAb-RBD complex shows that the IF motif at the tip of 47D1 CDR H2 interacts with a hydrophobic pocket in the RBD. Diverse immunoglobulin gene usage and convergent epitope targeting characterize neutralizing antibody responses to SARS-CoV-2, suggesting that vaccines that effectively present the receptor binding site on the RBD will likely elicit neutralizing antibody responses in a large fraction of the population.