Humoral immune response of BBIBP COVID-19 vaccination before and after the booster immunization

Evaluating long-term antibody responses to booster doses of COVID-19 vaccines in the Pakistani population

Background & Objective

Nearly 80 million of the Pakistani population received two doses of the BBIBP-CorV vaccine, against SARS-CoV-2, and 2.6 million people received heterologous booster doses up to February 2022. Our objective was to measure the long-term change of antibody titers in persons vaccinated with Pfizer-BioNTech COVID-19 following two doses of BBIBP-CorV.

Methods

Serum specimens from forty-three participants were collected 4-8 weeks following two doses of BBIBP-CorV at the Indus Hospital & Health Network, Karachi. A second set of serum specimens were collected 2-12 months after Pfizer-BioNTech COVID-19 booster dose administration. Chemiluminescent Microparticle Immunoassay (CMIA, Abbott Alinity Quant), and the pseudotyped lentivirus antibody neutralization assay were performed on all specimens. The latter assay was reported as log half-maximal inhibitory concentrations (IC50), calculated using a nonlinear regression algorithm (log [inhibitor] versus normalized response variable slope) in Graph Pad Prism 9. Paired sample t-test was used to ascertain the statistical significance of the difference in means of antibody titers obtained before and after the booster vaccine doses.

Results

Mean log10 values obtained with CMIA before and after the booster dose were 2.90 AU/mL and 3.87 AU/mL respectively, while the corresponding log10 IC50 values obtained through pseudotyped lentivirus antibody neutralization assay were 2.45 and 2.80. These differences were statistically significant with CMIA (p = <0.00001), but not with pseudotyped lentivirus antibody neutralization assay (p = 0.06318.).

Conclusion

A heterologous booster dose with Pfizer-BioNTech COVID-19 vaccine following two doses of BBIBP results in increased total antibody titers, though neutralizing antibody titers may start to wane a few months after the booster dose.

Nanovaccines for Advancing Long-Lasting Immunity against Infectious Diseases

Infectious diseases, particularly life-threatening pathogens such as small pox and influenza, have substantial implications on public health and global economies. Vaccination is a key approach to combat existing and emerging pathogens. Immunological memory is an essential characteristic used to evaluate vaccine efficacy and durability and the basis for the long-term effects of vaccines in protecting against future infections; however, optimizing the potency, improving the quality, and enhancing the durability of immune responses remains challenging and a focus for research involving investigation of nanovaccine technologies. In this review, we describe how nanovaccines can address the challenges for conventional vaccines in stimulating adaptive immune memory responses to protect against reinfection. We discuss protein and nonprotein nanoparticles as useful antigen platforms, including those with highly ordered and repetitive antigen array presentation to enhance immunogenicity through cross-linking with multiple B cell receptors, and with a focus on antigen properties. In addition, we describe how nanoadjuvants can improve immune responses by providing enhanced access to lymph nodes, lymphnode targeting, germinal center retention, and long-lasting immune response generation. Nanotechnology has the advantage to facilitate vaccine induction of long-lasting immunity against infectious diseases, now and in the future.

Probiotic-Fermented Distillers Grain Alters the Rumen Microbiome, Metabolome, and Enzyme Activity, Enhancing the Immune Status of Finishing Cattle

A total of 30 Simmental crossbred cattle (6.50 months old, 265.0 ± 22.48 kg) were randomly divided into three groups, with 10 heads per group, and fed for 45 days. The diet treatments consisted of the Control group without PFDG supplementation, the PFDG-15% group with 15% PFDG substituting for 15% concentrate, and PFDG-30% group with 30% PFDG substituting for 30% concentrate. The results showed that compared with the Control group, the average daily gain (ADG) of the cattle in the PFDG-30% group decreased significantly (0.890 vs. 0.768 kg/d, p = 0.005). The serum malondialdehyde content of cattle in the PFDG-15% and PFDG-30% groups decreased significantly (p = 0.047) compared to that of the Control group. However, the serum superoxide dismutase activity of cattle in the PFDG-30% group was significantly higher than that of the Control group (p = 0.047). Meanwhile, both the PFDG-15% and PFDG-30% groups (1758.47 vs. 2061.30 μg/mL) showed higher serum levels of immunoglobulin G, while the interleukin-10 concentration was lower in the PFDG-30% group (p = 0.027). In addition, the PFDG-15% and PFDG-30% groups shifted the rumen microbiota by improving the abundances of F082 (related to propionic acid production) and fiber-degrading bacteria (Lachnospiraceae_UGG-009 and Prevotellaceae_UCG-001) and reducing the abundance of the disease-associated bacteria Selenomonas. A Kyoto encyclopedia of genes and genomes (KEGG) analysis illustrated that three key metabolic pathways, including phenylalanine metabolism, pyrimidine metabolism, and tryptophan metabolism, were enriched in the PFDG-15% group, but eight key metabolic pathways, including arachidonic acid metabolism, were enriched in the PFDG-30% group. Importantly, both the PFDG-15% and PFDG-30% groups increased (p < 0.01) the activities of cellulase, lipase, and protease in the rumen. Finally, the different bacterial abundance in the rumen was associated with changes in the ADG, serum antioxidant capacity, immune status, rumen enzyme activity, and metabolites. These results suggest that PFDG alters rumen microbiome abundance, metabolome, and enzyme activity for enhancing serum antioxidant capacity and the immune status, but when the supplemental level reaches 30%, it has a negative effect on ADG and the anti-inflammatory factors in finishing cattle.

Immune-Boosting Effect of the COVID-19 Vaccine: Real-World Bidirectional Cohort Study

BACKGROUND

As the SARS-CoV-2 attenuates and antibodies from the COVID-19 vaccine decline, long-term attention should be paid to the durability of primary booster administration and the preventive effect of the second or multiple booster doses of the COVID-19 vaccine.

OBJECTIVE

This study aimed to explore the durability of primary booster administration and the preventive effect of second or multiple booster doses of the COVID-19 vaccine.

METHODS

We established a bidirectional cohort in Guizhou Province, China. Eligible participants who had received the primary booster dose were enrolled for blood sample collection and administration of the second booster dose. A retrospective cohort for the time of administration was constructed to evaluate antibody attenuation 6-12 months after the primary booster dose, while a prospective cohort on the vaccine effect of the second booster dose was constructed for 4 months after the second administration.

RESULTS

Between September 21, 2022, and January 30, 2023, a total of 327 participants were included in the final statistical analysis plan. The retrospective cohort revealed that approximately 6-12 months after receiving the primary booster, immunoglobulin G (IgG) slowly declined with time, while immunoglobulin A (IgA) remained almost constant. The prospective cohort showed that 28 days after receiving the second booster, the antibody levels were significantly improved. Higher levels of IgG and IgA were associated with better protection against COVID-19 infection for vaccine recipients. Regarding the protection of antibody levels against post-COVID-19 symptoms, the increase of the IgG had a protective effect on brain fog and sleep quality, while IgA had a protective effect on shortness of breath, brain fog, impaired coordination, and physical pain.

CONCLUSIONS

The IgG and IgA produced by the second booster dose of COVID-19 vaccines can protect against SARS-CoV-2 infection and may alleviate some post-COVID-19 symptoms. Further data and studies on secondary booster administration are required to confirm these conclusions.

The immunogenicity of Alum+CpG adjuvant SARS-CoV-2 inactivated vaccine in mice

The ongoing evolution and emergence of SARS-CoV-2 variants have raised concerns regarding the efficacy of existing vaccines and therapeutic agents. This study aimed to investigate the immunogenicity of an aluminum hydroxide (Alum) and CpG adjuvanted inactivated vaccine (IAV) candidate against SARS-CoV-2 in mice. A comparison was made between the immune response of mice vaccinated with the Alum+CpG adjuvant IAV and those vaccinated with the Alum adjuvant IAV. Mice immunized with Alum+CpG adjuvant IAV demonstrated high antibody titers and a durable humoral immune response, as well as a Th1-type cellular immune response. Notably, compared to Alum alone vaccine, the Alum+CpG adjuvant IAV induced significantly higher proportions of GC B cells in the splenocytes of immunized mice. Importantly, the changes in inflammatory cytokine levels in the sera of mice vaccinated with the Alum+CpG adjuvant IAV followed a similar trend to that of the Alum adjuvant IAV, which had been proven safe in clinical trials. Overall, our results demonstrate that Alum+CpG adjuvant has the potential to serve as a novel adjuvant, thereby providing valuable insights into the development of vaccine formulations.

Predictors of immune persistence induced by two-dose BBIBP-CorV vaccine in high-risk occupational population

BACKGROUND

The immune protection from infection may wane over time as neutralizing antibody levels decline. We aimed to develop a nomogram to predict long-term immune persistence induced by two-dose BBIBP-CorV vaccine and calculate the neutralizing antibody decline probability of individuals.

METHODS

In the initial study, a total of 809 participants were recruited and randomly allocated (1:1:1) to vaccination group with three two-dose schedules on days 0 and 14, 0 and 21, or 0 and 28. The participants with neutralizing antibody titers of 16 or above on day 28 after the second dose were followed up at month 3, 6 and 10. Multivariable Cox proportional hazards regression model and nomogram model were used to identify predictors associated with maintaining of neutralizing antibody levels during 10 months after the second dose.

RESULTS

A total of 744 participants followed up at day 28 after the second dose. The participants with age ≥ 50 (aHR = 3.556, 95 %CI: 1.141-4.884, P = 0.028) were associated with a high risk of response loss (titers < 16). The participants who were in 0-28 d group (aHR = 0.403, 95 %CI: 0.177-0.919, P = 0.031), had an influenza vaccination history (aHR = 0.468, 95 %CI: 0.267-0.921, P = 0.033) or were female (aHR = 0.542, 95 %CI: 0.269-0.935, P = 0.035) tended to maintain immune persistence during 10 months after the second dose. The nomogram was constructed and showed moderate discrimination[C-index:0.711 (95 %CI: 0.652-0.770); AUC: 0.731 (95 %CI: 0.663-0.792)] and good calibration.

CONCLUSIONS

From 28 days to 10 months after receipt of the second dose of the BBIBP-CorV vaccine, neutralizing antibody levels were substantially decreased, especially among men, among persons 50 years of age or older, among persons with the 0-14 d group, and among persons without history of influenza vaccination.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2100041705, ChiCTR2100041706.

SARS-CoV-2 neutralising antibody therapies: Recent advances and future challenges

The COVID-19 pandemic represents an unparalleled global public health crisis. Despite concerted research endeavours, the repertoire of effective treatment options remains limited. However, neutralising-antibody-based therapies hold promise across an array of practices, encompassing the prophylaxis and management of acute infectious diseases. Presently, numerous investigations into COVID-19-neutralising antibodies are underway around the world, with some studies reaching clinical application stages. The advent of COVID-19-neutralising antibodies signifies the dawn of an innovative and promising strategy for treatment against SARS-CoV-2 variants. Comprehensively, our objective is to amalgamate contemporary understanding concerning antibodies targeting various regions, including receptor-binding domain (RBD), non-RBD, host cell targets, and cross-neutralising antibodies. Furthermore, we critically examine the prevailing scientific literature supporting neutralising antibody-based interventions, and also delve into the functional evaluation of antibodies, with a particular focus on in vitro (vivo) assays. Lastly, we identify and consider several pertinent challenges inherent to the realm of COVID-19-neutralising antibody-based treatments, offering insights into potential future directions for research and development.

Association between levels of IgG antibodies from vaccines and Omicron symptomatic infection among children and adolescents in China

Background

Measurements of IgG antibodies to wild-type SARS-CoV-2 antigens can assess vaccine efficacy, but the absolute risk of Omicron symptomatic infection at different IgG levels for children and adolescents remains uncertain, as well as the minimum effective antibody level. We sought to determine the relationship between the tertiles of IgG antibodies to wild-type SARS-CoV-2 antigens and children with symptomatic infection of the pandemic and duration to negative conversion in China for the first time.

Methods

A retrospective study was conducted, including 168 participants under 18 years old from the No.2 People's Hospital of Lanzhou, China, diagnosed with Omicron variant BA.2.38 between July 8, 2022, and August 2, 2022. We calculated odds ratios (OR) in univariate and multivariate regression to assess the association of symptomatic infection with the tertiles of IgG, respectively. Kaplan-Meier curves and Cox proportional hazards regression were used to evaluate the relationship between IgG level and negative conversion time.

Results

The average age of the 168 children included in this study was 7.2 (4.7) years old, 133 (79.2%) were symptomatic patients, and the average negative conversion time was 12.2 (3.5) days. The participants with high IgG levels were less likely to become symptomatic, had a shorter turnaround time, and had higher values of IgM and nucleic acid CT. Compared to those with the lowest tertile of IgG, patients with the highest tertile had a 91% lower risk of developing a symptomatic infection after fully adjusting for confounders (OR = 0.09, 95% CI, 0.02-0.36, p = 0.001). There's no robust relationship between IgG level and negative conversion time in multivariate Cox regression.

Conclusion

The risk of developing a symptomatic infection can be predicted independently by tertiles of IgG antibodies to wild-type SARS-CoV-2 antigens. High IgG levels can inhibit viral replication, vastly reduce the risk of symptomatic infections and promote a virus-negative conversion, especially when IgG quantitative detection was ≥3.44 S/CO, a potential threshold for protection and booster strategy in the future. More data and research are needed in the future to validate the predictive models.

Unveiling a New Perspective on Distinguishing Omicron Breakthrough Cases and Postimmune COVID-19-Naive Individuals: Insights from Antibody Profiles

In the situation of mass vaccination against COVID-19, few studies have reported on the early kinetics of specific antibodies (IgG/IgM/IgA) of vaccine breakthrough cases. There is still a lack of epidemiological evidence about the value of serological indicators in the auxiliary diagnosis of COVID-19 infection, especially when the nucleic acid results were undetectable. Omicron breakthrough cases post-inactivated vaccination (n = 456) and COVID-19-naive individuals with two doses of inactivated vaccination (n = 693) were enrolled. Blood samples were collected and tested for SARS-CoV-2 antibody levels based on the magnetic chemiluminescence enzyme immunoassay. Among Omicron breakthrough cases, the serum IgG antibody level was 36.34 Sample/CutOff (S/CO) (95% confidence interval [CI], 31.89 to 40.79) in the acute phase and 88.45 S/CO (95% CI, 82.79 to 94.12) in the recovery phase. Serum IgA can be detected in the first week post-symptom onset (PSO) and showed an almost linear increase within 5 weeks PSO. Compared with those of breakthrough cases, IgG and IgA titers of the postimmune group were much lower (4.70 S/CO and 0.46 S/CO, respectively). Multivariate regression showed that serum IgG and IgA levels in Omicron breakthrough cases were mainly affected by the weeks PSO (P < 0.001). Receiver operating characteristic ROC0 curve analysis showed that the area under the curve (AUC) was 0.744 and 0.806 when the cutoff values of IgA and IgG were 1 S/CO and 15 S/CO, respectively. Omicron breakthrough infection can lead to a further increase in IgG and IgA levels relative to those of the immunized population. When nucleic acid real-time PCR was negative, we would use the kinetics of IgG and IgA levels to distinguish the breakthrough cases from the immunized population. IMPORTANCE This study fills a gap in the epidemiological evidence by investigating the value of serological indicators, particularly IgG and IgA levels, in the auxiliary diagnosis of COVID-19 infections when nucleic acid results are undetectable. The findings reveal that among Omicron breakthrough cases, both IgG and IgA antibody levels exhibit significant changes. Serum IgG levels increase during the acute phase and rise further in the recovery phase. Serum IgA can be detected as early as the first week post-symptom onset (PSO), showing a consistent linear increase within 5 weeks PSO. Furthermore, receiver operating characteristic (ROC) curve analysis demonstrates the potential of IgG and IgA cutoff values as diagnostic markers. The study's conclusion underscores the importance of monitoring IgG and IgA kinetics in distinguishing Omicron breakthrough cases from vaccinated individuals. These findings contribute to the development of more accurate diagnostic approaches and help inform public health strategies during the ongoing COVID-19 pandemic.

Inactivated vaccine fueled adaptive immune responses to Omicron in 2-year COVID-19 convalescents

Over 3 years, humans have experienced multiple rounds of global transmission of SARS-CoV-2 and its variants. In addition, the widely used vaccines against SARS-CoV-2 involve multiple strategies of development and inoculation. Thus, the acquired immunity established among humans is complicated, and there is a lack of understanding within a panoramic vision. Here, we provided the special characteristics of the cellular and humoral responses in 2-year convalescents after inactivated vaccines, in parallel to vaccinated COVID-19 naïve persons and unvaccinated controls. The decreasing trends of the IgG, IgA, and NAb, but not IgM of the convalescents were reversed by the vaccination. Both cellular and humoral immunity in convalescents after vaccination were higher than the vaccinated COVID-19 naïve persons. Notably, inoculation with inactivated vaccine fueled the NAb to BA.1, BA.2, BA.4, and BA.5 in 2-year convalescents, much higher than the NAb during 6 months and 1 year after symptoms onset. And no obvious T cell escaping to the S protein was observed in 2-year convalescents after inoculation. The study provides insight into the complicated features of human acquired immunity to SARS-CoV-2 and variants in the real world, indicating that promoting vaccine inoculation is essential for achieving herd immunity against emerging variants, especially in convalescents.

Characterization of stability, safety and immunogenicity of the mRNA lipid nanoparticle vaccine Iribovax® against COVID-19 in nonhuman primates

mRNA-lipid nanoparticle (mRNA-LNP) vaccines have proved their efficacy, versatility and unprecedented manufacturing speed during the COVID-19 pandemic. Here we report on the physicochemical properties, thermostability, immunogenicity, and protective efficacy of the nucleoside-modified mRNA-LNP vaccine candidate Iribovax® (also called SNEG2c). Injection of BALB/c mice, rabbits and nonhuman primates with two doses of SNEG2c induced production of high-titers of SARS-CoV-2 spike-specific and receptor-binding domain (RBD)-neutralizing antibodies in immunized animals. In addition to the strong humoral response, SNEG2c elicited substantial Th1-biased T-cell response. Sera from rhesus macaques immunized with a low dose of the vaccine showed robust spike-specific antibody titers 3-24× as high as those in convalescent sera from a panel of COVID-19 patients and 50% virus neutralization geometric mean titer of 1024 against SARS-CoV-2. Strikingly, immunization with SNEG2c completely cleared infectious SARS-CoV-2 from the upper and lower respiratory tracts of challenged macaques and protected them from viral-induced lung and trachea lesions. In contrast, the non-vaccinated macaques developed moderate to severe pulmonary pathology after the viral challenge. We present the results of repeat-dose and local tolerance toxicity and thermostability studies showing how the physicochemical properties of the mRNA-LNPs change over time and demonstrating that SNEG2 is safe, well tolerated and stable for long-term. These results support the planned human trials of SNEG2c.

Longitudinal study of humoral immunity against SARS-CoV-2 of health professionals in Brazil: the impact of booster dose and reinfection on antibody dynamics

Introduction

The pandemic caused by SARS-CoV-2 has had a major impact on health systems. Vaccines have been shown to be effective in improving the clinical outcome of COVID-19, but they are not able to fully prevent infection and reinfection, especially that caused by new variants.

Methods

Here, we tracked for 450 days the humoral immune response and reinfection in 52 healthcare workers from Brazil. Infection and reinfection were confirmed by RT-qPCR, while IgM and IgG antibody levels were monitored by rapid test.

Results

Of the 52 participants, 19 (36%) got reinfected during the follow-up period, all presenting mild symptoms. For all participants, IgM levels dropped sharply, with over 47% of them becoming seronegative by the 60th day. For IgG, 90% of the participants became seropositive within the first 30 days of follow-up. IgG antibodies also dropped after this period reaching the lowest level on day 270 (68.5 ± 72.3, p<0.0001). Booster dose and reinfection increased the levels of both antibodies, with the interaction between them resulting in an increase in IgG levels of 130.3 arbitrary units.

Conclusions

Overall, our data indicate that acquired humoral immunity declines over time and suggests that IgM and IgG antibody levels are not associated with the prevention of reinfection.

Neutralizing antibody levels associated with injectable and aerosolized Ad5-nCoV boosters and BA.2 infection

BACKGROUND

Several COVID-19 vaccines are in widespread use in China. Few data exist on comparative immunogenicity of different COVID-19 vaccines given as booster doses. We aimed to assess neutralizing antibody levels raised by injectable and inhaled aerosolized recombinant adenovirus type 5 (Ad5)-vectored COVID-19 vaccine as a heterologous booster after an inactivated COVID-19 vaccine two-dose primary series.

METHODS

Using an open-label prospective cohort design, we recruited 136 individuals who had received inactivated vaccine primary series followed by either injectable or inhaled Ad5-vectored vaccine and measured neutralizing antibody titers against ancestral SARS-CoV-2 virus and Omicron BA.1 and BA.5 variants. We also measured neutralizing antibody levels in convalescent sera from 39 patients who recovered from Omicron BA.2 infection.

RESULTS

Six months after primary series vaccination, neutralizing immunity against ancestral SARS-CoV-2 was low and neutralizing immunity against Omicron (B.1.1.529) was lower. Boosting with Ad5-vectored vaccines induced a high immune response against ancestral SARS-CoV-2. Neutralizing responses against Omicron BA.5 were ≥ 80% lower than against ancestral SARS-CoV-2 in sera from prime-boost subjects and in convalescent sera from survivors of Omicron BA.2 infection. Inhaled aerosolized Ad5-vectored vaccine was associated with greater neutralizing titers than injectable Ad5-vectored vaccine against ancestral and Omicron SARS-CoV-2 variants.

CONCLUSIONS

These findings support the current strategy of heterologous boosting with injectable or inhaled Ad5-vectored SARS-CoV-2 vaccination of individuals primed with inactivated COVID-19 vaccine.

Mix-and-match COVID-19 vaccines trigger high antibody response after the Third Dose Vaccine in Moroccan Health Care Workers

Recent studies have shown that in individuals who have received two doses of COVID-19 vaccine, the level of IgG antibodies decreased over time. In addition, the resurgence of the epidemic due to variants has led the authorities in several countries, including Morocco, to extend the third dose to the entire adult population. In this study, we included 43 healthcare workers (HCWs) who were vaccinated with three doses. They were vaccinated with ChAdOx1 nCoV-19 for the first two doses and with BNT 162b2 or BBIBP-CorV vaccine for the third dose. Humoral response was assessed on the day of injection of the third dose of vaccine and one month after the third dose by measuring anti-receptor-binding domain (RBD) IgG levels. Seven months after the second dose, the median titer of anti-RBD IgG was higher in the group with a history of SARS-CoV-2 infection than in the group with no history of infection (1038 AU/mL vs. 76.05 AU/mL, respectively, p=0.003). One month after the third dose, a significant increase in median level of anti-RBD in both groups was observed: from 76.05 AU/mL to 6127 AU/mL in the group with no history of infection and from 1038 AU/mL to 14412 AU/mL in the group with history of infection. Notably, the BNT 162b2 vaccine elicits a high titer of anti-RBD antibody compared to the BBIBP-CorV vaccine. Median antibody titers were 21991 AU/mL and 3640 AU/mL for BNT 162b2 and BBIBP-CorV vaccines, respectively (p=0.0002). 23% of HCWs were infected with SARS-CoV-2 within the first two months after the third dose injection. However, all these patients developed mild symptoms and tested negative by RT-qPCR between 10 and 15 days after the onset of symptoms. Our findings support that the third dose of COVID-19 vaccine significantly improves the humoral response and protects against the severe disease.

Review of therapeutic mechanisms and applications based on SARS-CoV-2 neutralizing antibodies

COVID-19 pandemic is a global public health emergency. Despite extensive research, there are still few effective treatment options available today. Neutralizing-antibody-based treatments offer a broad range of applications, including the prevention and treatment of acute infectious diseases. Hundreds of SARS-CoV-2 neutralizing antibody studies are currently underway around the world, with some already in clinical applications. The development of SARS-CoV-2 neutralizing antibody opens up a new therapeutic option for COVID-19. We intend to review our current knowledge about antibodies targeting various regions (i.e., RBD regions, non-RBD regions, host cell targets, and cross-neutralizing antibodies), as well as the current scientific evidence for neutralizing-antibody-based treatments based on convalescent plasma therapy, intravenous immunoglobulin, monoclonal antibodies, and recombinant drugs. The functional evaluation of antibodies (i.e., in vitro or in vivo assays) is also discussed. Finally, some current issues in the field of neutralizing-antibody-based therapies are highlighted.

Regulating the microenvironment with nanomaterials: Potential strategies to ameliorate COVID-19

COVID-19, caused by SARS-CoV-2, has resulted in serious economic and health burdens. Current treatments remain inadequate to extinguish the epidemic, and efficient therapeutic approaches for COVID-19 are urgently being sought. Interestingly, accumulating evidence suggests that microenvironmental disorder plays an important role in the progression of COVID-19 in patients. In addition, recent advances in nanomaterial technologies provide promising opportunities for alleviating the altered homeostasis induced by a viral infection, providing new insight into COVID-19 treatment. Most literature reviews focus only on certain aspects of microenvironment alterations and fail to provide a comprehensive overview of the changes in homeostasis in COVID-19 patients. To fill this gap, this review systematically discusses alterations of homeostasis in COVID-19 patients and potential mechanisms. Next, advances in nanotechnology-based strategies for promoting homeostasis restoration are summarized. Finally, we discuss the challenges and prospects of using nanomaterials for COVID-19 management. This review provides a new strategy and insights into treating COVID-19 and other diseases associated with microenvironment disorders.

Homologous booster immunization with an inactivated vaccine induced robust antibody response in healthcare workers: A retrospective study

Coronavirus Disease 2019 (Covid-19) severely impacted the health, society, and economy around the world. With declining protective efficacy of primary vaccination and the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, a Covid-19 booster vaccination is being fully implemented globally. Many people received three doses of BBIBP-CorV inactivated vaccine in China and other developing countries. However, the antibody response and immune persistence of the homologous BBIBP-CorV booster vaccination is yet to be thoroughly evaluated, as previous studies focused within one month after the third dose. In this study, 97 participants were enrolled to analyze the antibody response and immune persistence within 6 months as well as the safety within 7 days after the third-dose of homologous BBIBP-CorV inactivated vaccine. The seroconversion rate for total antibody against the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein were both 100% at month 1 and month 6 after the third dose. The IgG against the RBD of the SARS-CoV-2 S protein seroconversion rate increased from 42.27% before the third dose to 100% 1 month after the third dose and then slightly decreased to 98.97% 5 months later. Positive IgM against the RBD of the SARS-CoV-2 S protein was rare and was observed in only one participant at month 1 after the third dose. The neutralizing antibody levels at month 1 and month 6 after the third dose increased 63.32-fold and 13.16-fold compared with those before the third dose, and the positive rate for neutralizing antibody was still 100% at month 6 after the third dose. Importantly, the antibody responses induced by the vaccine and immune persistence were not affected by sex or age. No serious adverse reactions were reported. Total antibody and IgG against the RBD of the SARS-CoV-2 S protein were highly correlated with neutralizing antibody, suggesting that total antibody and IgG against the RBD of the SARS-CoV-2 S protein could be used as predictors for neutralizing antibody. In conclusion, the third dose of homologous BBIBP-CorV inactivated vaccine induced a robust antibody response and moderate immune persistence. These finding are of great significance for development future vaccination strategies.

Kinetics of SARS-CoV-2 neutralizing antibodies in Omicron breakthrough cases with inactivated vaccination: Role in inferring the history and duration of infection

Background

The quantitative level and kinetics of neutralizing antibodies (NAbs) in individuals with Omicron breakthrough infections may differ from those of vaccinated individuals without infection. Therefore, we aimed to evaluate the difference in NAb levels to distinguish the breakthrough cases from the post-immunized population to identify early infected person in an outbreak epidemic when nasal and/or pharyngeal swab nucleic acid real-time PCR results were negative.

Methods

We collected 1077 serum samples from 877 individuals, including 189 with Omicron BA.2 breakthrough infection and 688 post-immunized participants. NAb titers were detected using the surrogate virus neutralization test, and were log(2)-transformed to normalize prior to analysis using Student's unpaired t-tests. Geometric mean titers (GMT) were calculated with 95% confidence intervals (CI). Linear regression models were used to identify factors associated with NAb levels. We further conducted ROC curve analysis to evaluate the NAbs' ability to identify breakthrough infected individuals in the vaccinated population.

Results

The breakthrough infection group had a consistently higher NAb levels than the post-immunized group according to time since the last vaccination. NAb titers in the breakthrough infection group were 6.4-fold higher than those in the post-immunized group (GMT: 40.72 AU/mL and 6.38 AU/mL, respectively; p<0.0001). In the breakthrough infection group, the NAbs in the convalescent phase were 10.9-fold higher than in the acute phase (GMT: 200.48 AU/mL and 18.46 AU/mL, respectively; p<0.0001). In addition, the time since infection, booster vaccination, and the time since last vaccination were associated with log(2)-transformed NAb levels in the breakthrough infection group. ROC curve analysis showed that ROC area was largest (0.728) when the cut-off value of log(2)-transformed NAb was 6, which indicated that NAb levels could identify breakthrough infected individuals in the vaccinated population.

Conclusion

Our study demonstrates that the NAb titers of Omicron BA.2 variant breakthrough cases are higher than in the post-immunized group. The difference in NAb levels could be used to identify cases of breakthrough infection from the post-immunized population in an outbreak epidemic.

Immunogenicity assessment of elder hepatocellular carcinoma patients after inactivated whole-virion SARS-CoV-2 vaccination

BACKGROUND

Research on immunogenicity after 3rd SARS-CoV-2 vaccine in elder hepatocellular carcinoma (HCC) was limited. This study aimed to investigate the efficacy and influencing factors of inactivated SARS-CoV-2 vaccine in elder HCC.

RESEARCH DESIGN AND METHODS

We assessed total antibodies, anti-RBD IgG, and neutralizing antibodies (NAb) toward SARS-CoV-2 wild type (WT) as well as BA.4/5 in 304 uninfected HCC, 147 matched healthy control (HC), and 53 SARS-CoV-2 infected HCC, all aged over 60 years. The levels of antibodies were compared in the period 7-90, 91-180, and >180 days after 2nd or 3rd vaccination, respectively.

RESULTS

HCC had lower seropositivity than HC after 2nd dose (total antibodies, 64% vs. 92%, P < 0.0001; anti-RBD IgG, 50% vs. 77%, P < 0.0001). But 3rd dose can efficaciously close the gap (total antibodies, 96% vs. 100%, P = 0.1212; anti-RBD IgG: 87% vs. 87%, P > 0.9999). Booster effect of 3rd dose can persist >180 days in HCC (2nd vs. 3rd: total antibodies, 0.60 vs. 3.20, P < 0.0001; anti-RBD IgG, 13.86 vs. 68.85, P < 0.0001; WT NAb, 11.70 vs. 22.47, P < 0.0001). Vaccinated HCC had more evident humoral responses than unvaccinated ones after infection (total antibodies: 3.85 vs. 3.20, P < 0.0001; anti-RBD IgG: 910.92 vs. 68.85, P < 0.0001; WT NAb: 96.09 vs. 22.47, P < 0.0001; BA.4/5 NAb: 86.53 vs. 5.59, P < 0.0001).

CONCLUSIONS

Our findings highlight the booster effect and protective role of 3rd dose. Our results could provide a theoretical foundation for informing decisions regarding SARS-CoV-2 vaccination in elder HCC.

Immune persistence induced by two-dose BBIBP-CorV vaccine with different intervals, and immunogenicity and safety of a homologous booster dose in high-risk occupational population

BACKGROUND

The immune persistence of neutralizing antibodies elicited by BBIBP-CorV vaccines on day 0-14, 0-21 and 0-28 schedule, and the immunogenicity and safety of a homologous booster dose after different priming vaccination regimens is scarcely reported.

METHODS

: Responders (GMT≥16) at day 28, after priming with the two-dose vaccine, were followed up at 3, 6, and 10 months. Eligible participants received a homologous booster dose at month 10 and were followed-up 28 days post-booster.

RESULTS

The GMT of neutralizing antibodies in 0-28d-10 m and 0-21d-10 m group were significantly higher than 0-14d-10 m group from month 3 (71.6 & 64.2 vs 46.4, p < 0.001) to month 10 (32.4 & 28.8 vs 20.3, p < 0.001) after the second dose. On day 28 post-booster, a remarkable rebound in neutralizing antibodies (246.2, 277.5, and 288.6, respectively) was observed in the three groups. All adverse reactions were mild after booster injection.

CONCLUSIONS

The priming two-dose BBIBP-CorV vaccine with 0-28 days and 0-21 days schedule could lead to a longer persistence of neutralizing antibody than the 0-14 days schedule. Regardless of the priming vaccination regimens, a homologous booster dose led to a strong rebound in neutralizing antibodies and might persist for at least 18 months.

The BBIBP-CorV inactivated COVID-19 vaccine induces robust and persistent humoral responses to SARS-CoV-2 nucleocapsid, besides spike protein in healthy adults

Vaccination is one of the best ways to control the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic. Among the various SARS-CoV-2 vaccines approved for use, the BBIBP-CorV inactivated vaccine has been widely used in 93 countries. In order to understand deeply the protective mechanism of inactivated vaccine, which retains all antigenic components of live virus, the analysis of humoral responses triggered by multiple proteins is necessary. In this research, antibody responses were generated with 6 selected recombinant proteins and 68 overlapping peptides that completely covered SARS-CoV-2 nucleocapsid (N) protein in 254 healthy volunteers vaccinated with BBIBP-CorV. As a result, antibody responses to the receptor binding domain (RBD), N, and non-structural protein 8 (NSP8) were induced following immunization by BBIBP-CorV. The antibody responses detected in donors after the 2nd dose vaccination can be maintained for about 6 months. Moreover, specific antibody levels can be restored after the boosting vaccination measured by ELISA. Furthermore, the level of SARS-CoV-2 specific IgG response is independent of age and gender. Moreover, N391-408 was identified as a dominant peptide after vaccination of BBIBP-CorV through peptide screening. Understanding the overview of humoral reactivity of the vaccine will contribute to further research on the protective mechanism of the SARS-CoV-2 inactivated vaccine and provide potential biomarkers for the related application of inactivated vaccine.

Immunoassay and mass cytometry revealed immunological profiles induced by inactivated BBIBP COVID-19 vaccine

With the global prevalence of COVID-19 and the constant emergence of viral variants, boosters for COVID-19 vaccines to enhance antibody titers in human bodies will become an inevitable trend. However, there is a lack of data on antibody levels and the protective effects of booster injections. This study monitored and analyzed the antibody potency and the antibody responses induced by the booster injection in the subjects who received three vaccine doses. The study was conducted in a multicenter collaboration and recruited 360 healthy adults aged 20-74. Participants received the first, second, and booster doses of inactivated Sinopharm/BBIBP COVID-19 vaccine at 0, 1, and 7 months. Vaccine-induced virus-specific antibody levels (SARS-COV-2-IgA/IgM/IgG) were monitored at multiple time points, surrogate virus neutralization test (sVNT), and the spatial distribution and proportion of immune cells and markers were analyzed using the CyTOF method before vaccination and a month after the second dose. The titers of SARS-CoV-2-IgA/IgM/IgG and neutralizing antibodies increased to a high level in the first month after receiving the second dose of vaccine and declined slowly after that. The antibody levels of SARS-CoV-2-IgG and sVNT were significantly increased at 0.5 months after the induction of the booster (p < 0.05). Despite a downward trend, the antibody levels were still high in the following 6 months. The B cell concentration (in humoral sample) a month after the second injection was significantly reduced compared to that before the vaccine injection (p < 0.05). The proportion of the C01 cell cluster was significantly decreased compared with that before vaccine injection (p < 0.05). Individual cell surface markers showed distinctions in spatial distribution but were not significantly different. This study has shown that serum antibody titer levels will decrease with time by monitoring and analyzing the antibody efficacy and the antibody reaction caused by the booster injection of healthy people who received the whole vaccination (completed three injections). Still, the significant peak of the antibody titer levels after booster highlights the recall immune response. It can maintain a high concentration of antibody levels for a long time, which signifies that the protection ability has been enhanced following the injection of booster immunization. Additionally, CyTOF data shows the active production of antibodies and the change in the immunity environment.

Heterologous booster with inhaled Adenovirus vector COVID-19 vaccine generated more neutralizing antibodies against different SARS-CoV-2 variants

The rapid widespread Omicron subvariant BA.5 of SARS-CoV-2 has become a potential imminent pandemic threat, but available vaccines lack high efficacy against this subvariant. Thus, it is urgent to find highly protective vaccination strategies within available SARS-CoV-2 vaccines. Here, by using a SARS-CoV-2 pseudovirus neutralization assay, we demonstrated that the aerosol inhalation of adenoviral vector COVID-19 vaccine after two dose of inactivated vaccine (I-I-Ad5) led to higher levels of neutralizing antibodies against D614G strain (2041.00[95% CI, 1243.00-3351.00] vs 249.00[149.10-415.70]), Omicron BA.2 (467.10[231.00-944.40] vs 72.21[39.31-132.70]), BA.2.12.1(348.5[180.3-673.4] vs 53.17[31.29-90.37]), BA.2.13 (410.40[190.70-883.3] vs 48.48[27.87-84.32]), and BA.5 (442.40 vs 56.08[35.14-89.51]) than three inactivated vaccine doses (I-I-I). Additionally, the level of neutralizing antibodies against BA.5 induced by I-I-Ad5 was 2.41-fold higher than those boosted by a third dose of RBD subunit vaccine (I-I-S) (p = 0.1308). The conventional virus neutralizing assay confirmed that I-I-Ad5 induced higher titer of neutralizing antibodies than I-I-I (116.80[84.51-161.5] vs 4.40[4.00-4.83]). In addition, I-I-Ad5 induced higher, but later, anti-RBD IgG and IgA in plasma than I-I-I. Our study verified that mucosal immunization with aerosol inhalation of adenoviral vector COVID-19 vaccine may be an effective strategy to control the probable wave of BA.5 pandemic in addition to two inactivated vaccines.

Exploring the Willingness of the COVID-19 Vaccine Booster Shots in China Using the Health Belief Model: Web-Based Online Cross-Sectional Study

(1) Objective: To explore Chinese residents’ willingness to receive COVID-19 vaccine booster shots and identify predictors of the level of willingness based on the health belief model (HBM). (2) Methods: The snowball sampling method was used to distribute online questionnaires. A chi-square test was used to analyze the relationship between different variables. The causal relationship between HBM-related factors and booster vaccination intentions was explored by Structural equation modeling (SEM). (3) Results: A total of 898 complete responses were included; 64.3% had already received the booster injection. Most respondents intended to vaccinate themselves, while 16.1% were hesitant. Nearly half of the respondents chose to take the booster injection to support China’s vaccination policy. Using the SEM, perceived susceptibility and perceived barriers were found to have a negative effect on booster vaccination intentions, whereas perceived benefit and cues to action positively affected booster vaccination intentions in the HBM. (4) Conclusions: Factors included in this study have different effects on the willingness to take the COVID-19 booster injections. Sociodemographic characteristics and characteristics of participants’ COVID-19 vaccination have a significant effect on the willingness to receive vaccine booster shots. The HBM constructs can serve as good predictors of the acceptance of vaccine booster shots with the exception of perceived severity, which may benefit health officials in terms of conducting targeted strategies in vaccine programs.

Immunogenicity and immune-persistence of the CoronaVac or Covilo inactivated COVID-19 Vaccine: a 6-month population-based cohort study

Background

Owing to the coronavirus disease 2019 (COVID-19) pandemic and the emergency use of different types of COVID-19 vaccines, there is an urgent need to consider the effectiveness and persistence of different COVID-19 vaccines.

Methods

We investigated the immunogenicity of CoronaVac and Covilo, two inactivated vaccines against COVID-19 that each contain inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The levels of neutralizing antibodies to live SARS-CoV-2 and the inhibition rates of neutralizing antibodies to pseudovirus, as well as the immunoglobulin (Ig)G and IgM responses towards the spike (S) and nucleocapsid (N) protein of SARS-CoV-2 at 180 days after two-dose vaccination were detected.

Results

The CoronaVac and Covilo vaccines induced similar antibody responses. Regarding neutralizing antibodies to live SARS-CoV-2, 77.9% of the CoronaVac vaccine recipients and 78.3% of the Covilo vaccine recipients (aged 18–59 years) seroconverted by 28 days after the second vaccine dose. Regarding SARS-CoV-2-specific antibodies, 97.1% of the CoronaVac vaccine recipients and 95.7% of the Covilo vaccine recipients seroconverted by 28 days after the second vaccine dose. The inhibition rates of neutralizing antibody against a pseudovirus of the SARS-CoV-2 Delta variant were significantly lower compared with those against a pseudovirus of wildtype SARS-CoV-2. Associated with participant characteristics and antibody levels, persons in the older age group and with basic disease, especially a chronic respiratory disease, tended to have lower anti-SARS-CoV-2 antibody seroconversion rates.

Conclusion

Antibodies that were elicited by these two inactivated COVID-19 vaccines appeared to wane following their peak after the second vaccine dose, but they persisted at detectable levels through 6 months after the second vaccine dose, and the effectiveness of these antibodies against the Delta variant of SARS-CoV-2 was lower than their effectiveness against wildtype SARS-CoV-2, which suggests that attention must be paid to the protective effectiveness, and its persistence, of COVID-19 vaccines on SARS-CoV-2 variants.

Immunogenicity Following Two Doses of the BBIBP-CorV Vaccine and a Third Booster Dose with a Viral Vector and mRNA COVID-19 Vaccines against Delta and Omicron Variants in Prime Immunized Adults with Two Doses of the BBIBP-CorV Vaccine

Coronavirus disease 2019 (COVID-19) booster vaccination is being comprehensively evaluated globally due to waning immunity and the emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. Therefore, this study aimed to evaluate antibody responses in individuals vaccinated with two doses of the BBIBP-CorV vaccine and to explore the boosting effect of the different vaccine platforms in BBIBP-CorV-primed healthy adults, including a viral vector vaccine (AZD122) and mRNA vaccines (BNT162b2 and mRNA-1273). The results showed that in the BBIBP-CorV prime group, the total receptor-binding domain (RBD) immunoglobulin (Ig) and anti-RBD IgG levels waned significantly at three months after receiving the second dose. However, after the booster, RBD-specific binding antibody levels increased. Neutralizing antibody measured by a surrogate neutralization test showed inhibition over 90% against the SARS-CoV-2 delta variant but less than 70% against the omicron variant after the third dose on day 28. All booster vaccines could induce the total IFN-ɣ T-cell response. The reactogenicity was acceptable and well-tolerated without serious adverse events. This study supports the administration of the third dose with either a viral vector or mRNA vaccine for BBIBP-CorV-primed individuals to stimulate antibody and T-cell responses.

Neutralizing Antibody Response to BBIBP-CorV in Comparison with COVID-19 Recovered, Unvaccinated Individuals in a Sample of the Pakistani Population

Fifty five percent of the Pakistani population is still unvaccinated with the two-dose protocol of COVID-19 vaccines. This study was undertaken to determine the seroconversion rate and antibody titers following the two-dose BBIBP-CorV protocol, and to compare these variables in unvaccinated, COVID-19 recovered individuals (total n = 180) at Indus Hospital and Health Network, Karachi. Pseudotyped lentivirus antibody neutralization assays and SARS-CoV-2 IgG Quant II (Abbott) immunoassays were performed 4-8 weeks following the second dose of the BBIBP-CorV or PCR positivity/onset of symptoms of COVID-19. Seroconversion rate, using neutralization assays, in vaccinated individuals was lower (78%) than that in unvaccinated, COVID-19-recovered individuals with moderate to severe infection (97%). Prior PCR positivity increased serocoversion rate to 98% in vaccinated individuals. Immunoassays did not, however, reveal significant inter-group differences in seroconversion rates (≥95% in all groups). Log10 mean antibody neutralizing titers following the two-dose BBIBP-CorV protocol (IC50 = 2.21) were found to be significantly less than those succeeding moderate to severe COVID-19 (IC50 = 2.94). Prior SARS-CoV-2 positivity significantly increased post-vaccination antibody titers (IC50 = 2.82). Similar inter-group titer differences were obtained using the immunoassay. BBIBP-CorV post-vaccination titers may, thus, be lower than those following natural, moderate to severe infection, while prior SARS-CoV-2 exposure increases these titers to more closely approximate the latter.