Safety and Efficacy of Single-Dose Ad26.COV2.S Vaccine against Covid-19

Impact of SARS-CoV-2 vaccines on Covid-19 incidence and mortality in the United States

BACKGROUND

Given the waning of vaccine effectiveness and the shifting of the most dominant strains in the U.S., it is imperative to understand the association between vaccination coverage and Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) disease and mortality at the community levels and whether that association might vary according to the dominant SARS-CoV-2 strains in the U.S.

METHODS

Generalized estimating equations were used to estimate associations between U.S. county-level cumulative vaccination rates and booster distribution and the daily change in county-wide Coronavirus 2019 disease (COVID-19) risks and mortality during Alpha, Delta and Omicron predominance. Models were adjusted for potential confounders at both county and state level. A 2-week lag and a 4-week lag were introduced to assess vaccination rate impact on incidence and mortality, respectively.

RESULTS

Among 3,073 counties in 48 states, the average county population complete vaccination rate of all age groups was 50.79% as of March 11th, 2022. Each percentage increase in vaccination rates was associated with reduction of 4% (relative risk (RR) 0.9607 (95% confidence interval (CI): 0.9553, 0.9661)) and 3% (RR 0.9694 (95% CI: 0.9653, 0.9736)) in county-wide COVID-19 cases and mortality, respectively, when Alpha was the dominant variant. The associations between county-level vaccine rates and COVID-19 incidence diminished during the Delta and Omicron predominance. However, each percent increase in people receiving a booster shot was associated with reduction of 6% (RR 0.9356 (95% CI: 0.9235, 0.9479)) and 4% (RR 0.9595 (95% CI: 0.9431, 0.9761)) in COVID-19 incidence and mortality in the community, respectively, during the Omicron predominance.

CONCLUSIONS

Associations between complete vaccination rates and COVID-19 incidence and mortality appeared to vary with shifts in the dominant variant, perhaps due to variations in vaccine efficacy by variant or to waning vaccine immunity over time. Vaccine boosters were associated with notable protection against Omicron disease and mortality.

Multiple Sclerosis Onset before and after COVID-19 Vaccination: Can HLA Haplotype Be Determinant?

A few cases of multiple sclerosis (MS) onset after COVID-19 vaccination have been reported, although the evidence is insufficient to establish causality. The aim of this study is to compare cases of newly diagnosed relapsing-remitting MS before and after the outbreak of the COVID-19 pandemic and the impact of COVID-19 vaccination. Potential environmental and genetic predisposing factors were also investigated, as well as clinical patterns. This is a single-centre retrospective cohort study including all patients who presented with relapsing-remitting MS onset between January 2018 and July 2022. Data on COVID-19 vaccination administration, dose, and type were collected. HLA-DRB1 genotyping was performed in three subgroups. A total of 266 patients received a new diagnosis of relapsing-remitting MS in our centre, 143 before the COVID-19 pandemic (until and including March 2020), and 123 during the COVID-19 era (from April 2020). The mean number of new MS onset cases per year was not different before and during the COVID-19 era and neither were baseline patients' characteristics, type of onset, clinical recovery, or radiological patterns. Fourteen (11.4%) patients who subsequently received a new diagnosis of MS had a history of COVID-19 vaccination within one month before symptoms onset. Patients' characteristics, type of onset, clinical recovery, and radiological patterns did not differ from those of patients with non-vaccine-related new diagnoses of MS. The allele frequencies of HLA-DRB1*15 were 17.6% and 22.2% in patients with non-vaccine-related disease onset before and during the COVID-19 era, respectively, while no case of HLA-DRB1*15 was identified among patients with a new diagnosis of MS post-COVID-19 vaccine. In contrast, HLA-DRB1*08+ or HLA-DRB1*10+ MS patients were present only in this subgroup. Although a causal link between COVID-19 vaccination and relapsing-remitting MS cannot be detected, it is interesting to note and speculate about the peculiarities and heterogeneities underlying disease mechanisms of MS, where the interactions of genetics and the environment could be crucial also for the follow-up and the evaluation of therapeutic options.

Messenger RNA Vaccine Technology: Success for SARS-CoV-2 and Prospects for an HIV-1 Vaccine

Over the past several years, messenger RNA (mRNA) vaccine has evolved from a term familiar only to vaccine scientists into one easily recognized by much of the general population. This change occurred because of the remarkable success of effective and safe mRNA vaccines during the COVID-19 pandemic that saved countless lives. Although mRNA vaccine technology has a clear use for combating future emerging diseases, its role in fighting currently known pathogens, such as HIV-1, is not well defined. This review summarizes mRNA vaccine technology, highlighting its success during the COVID-19 pandemic. It then addresses past and current efforts to develop a vaccine for HIV-1, including how mRNA vaccine technology has created opportunities in the ongoing search for an effective HIV-1 vaccine.

SARS-CoV-2 resistance to monoclonal antibodies and small-molecule drugs

Over four years have passed since the beginning of the COVID-19 pandemic. The scientific response has been rapid and effective, with many therapeutic monoclonal antibodies and small molecules developed for clinical use. However, given the ability for viruses to become resistant to antivirals, it is perhaps no surprise that the field has identified resistance to nearly all of these compounds. Here, we provide a comprehensive review of the resistance profile for each of these therapeutics. We hope that this resource provides an atlas for mutations to be aware of for each agent, particularly as a springboard for considerations for the next generation of antivirals. Finally, we discuss the outlook and thoughts for moving forward in how we continue to manage this, and the next, pandemic.

Mucosal Vaccination with a Newcastle Disease Virus-Vectored Vaccine Reduces Viral Loads in SARS-CoV-2-Infected Cynomolgus Macaques

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged following an outbreak of unexplained viral illness in China in late 2019. Since then, it has spread globally causing a pandemic that has resulted in millions of deaths and has had enormous economic and social consequences. The emergence of SARS-CoV-2 saw the rapid and widespread development of a number of vaccine candidates worldwide, and this never-before-seen pace of vaccine development led to several candidates progressing immediately through clinical trials. Many countries have now approved vaccines for emergency use, with large-scale vaccination programs ongoing. Despite these successes, there remains a need for ongoing pre-clinical and clinical development of vaccine candidates against SARS-CoV-2, as well as vaccines that can elicit strong mucosal immune responses. Here, we report on the efficacy of a Newcastle disease virus-vectored vaccine candidate expressing SARS-CoV-2 spike protein (NDV-FLS) administered to cynomolgus macaques. Macaques given two doses of the vaccine via respiratory immunization developed robust immune responses and had reduced viral RNA levels in nasal swabs and in the lower airway. Our data indicate that NDV-FLS administered mucosally provides significant protection against SARS-CoV-2 infection, resulting in reduced viral burden and disease manifestation, and should be considered as a viable candidate for clinical development.

High-flow nasal oxygen in resource-constrained, non-intensive, high-care wards for COVID-19 acute hypoxaemic respiratory failure: Comparing outcomes of the first v. third waves at a tertiary centre in South Africa

Background

High-flow nasal oxygen (HFNO) is an accepted treatment for severe COVID-19-related acute hypoxaemic respiratory failure (AHRF).

Objectives

To determine whether treatment outcomes at Groote Schuur Hospital, Cape Town, South Africa, during the third COVID-19 wave would be affected by increased institutional experience and capacity for HNFO and more restrictive admission criteria for respiratory high-care wards and intensive care units.

Methods

We included consecutive patients with COVID-19-related AHRF treated with HFNO during the first and third COVID-19 waves. The primary endpoint was comparison of HFNO failure (composite of the need for intubation or death while on HFNO) between waves.

Results

A total of 744 patients were included: 343 in the first COVID-19 wave and 401 in the third. Patients treated with HFNO in the first wave were older (median (interquartile range) age 53 (46 - 61) years v. 47 (40 - 56) years; p<0.001), and had higher prevalences of diabetes (46.9% v. 36.9%; p=0.006), hypertension (51.0% v. 35.2%; p<0.001), obesity (33.5% v. 26.2%; p=0.029) and HIV infection (12.5% v. 5.5%; p<0.001). The partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2 /FiO2 ) ratio at HFNO initiation and the ratio of oxygen saturation/FiO2 to respiratory rate within 6 hours (ROX-6 score) after HFNO commencement were lower in the first wave compared with the third (median 57.9 (47.3 - 74.3) mmHg v. 64.3 (51.2 - 79.0) mmHg; p=0.005 and 3.19 (2.37 - 3.77) v. 3.43 (2.93 - 4.00); p<0.001, respectively). The likelihood of HFNO failure (57.1% v. 59.6%; p=0.498) and mortality (46.9% v. 52.1%; p=0.159) did not differ significantly between the first and third waves.

Conclusion

Despite differences in patient characteristics, circulating viral variant and institutional experience with HFNO, treatment outcomes were very similar in the first and third COVID-19 waves. We conclude that once AHRF is established in COVID-19 pneumonia, the comorbidity profile and HFNO provider experience do not appear to affect outcome.

Study synopsis

What the study adds. This study adds to the body of evidence demonstrating the utility of high-flow nasal oxygen (HFNO) in avoiding invasive mechanical ventilation (IMV) in patients with severe COVID-19 hypoxaemic respiratory failure, and shows that this utility remained consistent across different waves of the COVID-19 pandemic.Implications of the study. In resource-constrained settings, HFNO is a feasible non-invasive alternative to IMV and can be employed with favourable and consistent outcomes outside traditional critical care wards. It also confirms that the degree of gas exchange abnormality, and not pre-existing patient-related factors, circulating wave variant or provider experience, is the main predictor of HFNO failure.

Second booster dose improves antibody neutralization against BA.1, BA.5 and BQ.1.1 in individuals previously immunized with CoronaVac plus BNT162B2 booster protocol

Introduction

SARS-CoV-2 vaccines production and distribution enabled the return to normalcy worldwide, but it was not fast enough to avoid the emergence of variants capable of evading immune response induced by prior infections and vaccination. This study evaluated, against Omicron sublineages BA.1, BA.5 and BQ.1.1, the antibody response of a cohort vaccinated with a two doses CoronaVac protocol and followed by two heterologous booster doses.

Methods

To assess vaccination effectiveness, serum samples were collected from 160 individuals, in 3 different time points (9, 12 and 18 months after CoronaVac protocol). For each time point, individuals were divided into 3 subgroups, based on the number of additional doses received (No booster, 1 booster and 2 boosters), and a viral microneutralization assay was performed to evaluate neutralization titers and seroconvertion rate.

Results

The findings presented here show that, despite the first booster, at 9m time point, improved neutralization level against omicron ancestor BA.1 (133.1 to 663.3), this trend was significantly lower for BQ.1.1 and BA.5 (132.4 to 199.1, 63.2 to 100.2, respectively). However, at 18m time point, the administration of a second booster dose considerably improved the antibody neutralization, and this was observed not only against BA.1 (2361.5), but also against subvariants BQ.1.1 (726.1) and BA.5 (659.1). Additionally, our data showed that, after first booster, seroconvertion rate for BA.5 decayed over time (93.3% at 12m to 68.4% at 18m), but after the second booster, seroconvertion was completely recovered (95% at 18m).

Discussion

Our study reinforces the concerns about immunity evasion of the SARS-CoV-2 omicron subvariants, where BA.5 and BQ.1.1 were less neutralized by vaccine induced antibodies than BA.1. On the other hand, the administration of a second booster significantly enhanced antibody neutralization capacity against these subvariants. It is likely that, as new SARS-CoV-2 subvariants continue to emerge, additional immunizations will be needed over time.

Seroepidemiological assessment of SARS-CoV-2 vaccine responsiveness and associated factors in the vaccinated community of the Casablanca-Settat Region, Morocco

Assessing the prevalence of SARS-CoV-2 IgG positivity through population-based serological surveys is crucial for monitoring COVID-19 vaccination efforts. In this study, we evaluated SARS-CoV-2 IgG positivity within a provincial cohort to understand the magnitude of the humoral response against the SARS-CoV-2 vaccine and to inform evidence-based public health decisions. A community-based cross-sectional seroprevalence study was conducted, involving 10,669 participants who received various vaccines (two doses for BBIBP-CorV/Sinopharm, Covishield vaccine, and Pfizer/BioNTech, and one dose for Johnson & Johnson's Janssen COVID-19 vaccine). The study spanned 16 provinces in the Casablanca-Settat region from February to June 2022, during which comprehensive demographic and comorbidity data were collected. We screened samples for the presence of IgG antibodies using the SARS-CoV-2 IgG II Quant assay, which quantifies antibodies against the receptor-binding domain (RBD) of the spike (S) protein, measured on the Abbott Architect i2000SR. The overall crude seroprevalence was 96% (95% CI: 95.6-96.3%), and after adjustment for assay performance, it was estimated as 96.2% (95% CI: 95.7-96.6). The adjusted overall seroprevalences according to vaccine brands showed no significant difference (96% for BBIBP-CorV/Sinopharm, 97% for ChAdOx1 nCoV-19/Oxford/AstraZeneca, 98.5% for BNT162b2/Pfizer-BioNTech, and 98% for Janssen) (p = 0.099). Participants of older age, female sex, those with a history of previous COVID-19 infection, and those with certain chronic diseases were more likely to be seropositive among ChAdOx1 nCoV-19/Oxford/AstraZeneca and BBIBP-CorV/Sinopharm vaccinee groups. Median RBD antibody concentrations were 2355 AU/mL, 3714 AU/mL, 5838 AU/mL, and 2495 AU/mL, respectively, after two doses of BBIBP-CorV/Sinopharm, ChAdOx1 nCoV-19/Oxford/AstraZeneca, BNT162b2/Pfizer-BioNTech, and after one dose of Janssen (p < 0.0001). Furthermore, we observed that participants vaccinated with ChAdOx1 nCoV-19/Oxford/AstraZeneca and BBIBP-CorV/Sinopharm with comorbid chronic diseases exhibited a more pronounced response to vaccination compared to those without comorbidities. In contrast, no significant differences were observed among Pfizer-vaccinated participants (p > 0.05). In conclusion, our serosurvey findings indicate that all four investigated vaccines provide a robust humoral immune response in the majority of participants (more than 96% of participants had antibodies against SARS-CoV-2). The BNT162b2 vaccine was found to be effective in eliciting a strong humoral response compared to the other three vaccines. However, challenges still remain in examining the dynamics and durability of immunoprotection in the Moroccan context.

Immunogenicity and efficacy of VLA2001 vaccine against SARS-CoV-2 infection in male cynomolgus macaques

BACKGROUND

The fight against COVID-19 requires mass vaccination strategies, and vaccines inducing durable cross-protective responses are still needed. Inactivated vaccines have proven lasting efficacy against many pathogens and good safety records. They contain multiple protein antigens that may improve response breadth and can be easily adapted every year to maintain preparedness for future seasonally emerging variants.

METHODS

The vaccine dose was determined using ELISA and pseudoviral particle-based neutralization assay in the mice. The immunogenicity was assessed in the non-human primates with multiplex ELISA, neutralization assays, ELISpot and intracellular staining. The efficacy was demonstrated by viral quantification in fluids using RT-qPCR and respiratory tissue lesions evaluation.

RESULTS

Here we report the immunogenicity and efficacy of VLA2001 in animal models. VLA2001 formulated with alum and the TLR9 agonist CpG 1018™ adjuvant generate a Th1-biased immune response and serum neutralizing antibodies in female BALB/c mice. In male cynomolgus macaques, two injections of VLA2001 are sufficient to induce specific and polyfunctional CD4+ T cell responses, predominantly Th1-biased, and high levels of antibodies neutralizing SARS-CoV-2 infection in cell culture. These antibodies also inhibit the binding of the Spike protein to human ACE2 receptor of several variants of concern most resistant to neutralization. After exposure to a high dose of homologous SARS-CoV-2, vaccinated groups exhibit significant levels of protection from viral replication in the upper and lower respiratory tracts and from lung tissue inflammation.

CONCLUSIONS

We demonstrate that the VLA2001 adjuvanted vaccine is immunogenic both in mouse and NHP models and prevent cynomolgus macaques from the viruses responsible of COVID-19.

Oncolytic adenoviruses and immunopeptidomics: a convenient marriage

Oncolytic viruses (OVs) are biological therapeutic agents that selectively destroy cancer cells while sparing normal healthy cells. Besides direct oncolysis, OV infection induces a proinflammatory shift in the tumor microenvironment and the release of tumor-associated antigens (TAAs) that might induce an anti-tumor immunity. Due to their immunostimulatory effect, OVs have been explored for cancer vaccination against specific TAAs. However, this approach usually requires genetic modification of the virus and the production of a new viral vector for each target, which is difficult to implement for low prevalent antigens. In a recent study, Chiaro et al. presented an elegant proof of concept on how to implement the PeptiCRAd vaccination platform to overcome this limitation for the treatment of mesothelioma. Authors showed the feasibility of identifying immunogenic TAAs in human mesothelioma and using them to coat oncolytic adenovirus particles. The result was a customized virus-based cancer vaccine that circumvents time and resource-consuming steps incurred from genetically engineering viruses. Although some questions remain to be addressed, this interesting approach suggests novel strategies for personalized cancer medicine using oncolytic virotherapy.

SARS-CoV-2 antibody vaccine response in Inflammatory Bowel Disease patients with positive anti-nucleocapsid serology or history of COVID-19 infection

Background

Previous history of COVID-19 infection is a natural booster of the vaccine response in the general population. The response to COVID-19 vaccines is lessened in Inflammatory Bowel Disease patients on selected class of immunosuppressive treatments.

Aims

The study was to assess anti-SARS-CoV-2 spike-specific IgG antibody response in Inflammatory Bowel Disease patients with a history of COVID-19 infection.

Patients and methods

This single-center prospective study involved 504 Inflammatory Bowel Disease patients. Demographic data and clinical data were gathered through questionnaires and patient charts. Anti-SARS-CoV-2 spike-specific and antinucleocapsid antibody levels were measured at T1, T2 (after the 2-dose series), and T3 or T4 (booster vaccine).

Results

This study included 504 Inflammatory Bowel Disease patients, and 234 completed one year follow-up with blood tests. Positive anti-nucleocapsid serology or history of COVID-19 infection was significantly associated with increased median anti- SARS-CoV-2 spike-specific IgG titers after the 2-dose series (1930 BAU/mL vs. 521 BAU/mL p < 0.0001) and the booster vaccine (4390 BAU/mL vs. 2160 BAU/mL, p = 0.0156). Multivariate analysis showed that higher anti-SARS-CoV-2 spike-specific IgG levels were independently associated with anti-nucleocapsid antibodies at T2 (OR=2.23, p < 0.0001) and T3 (OR=1.72, p = 0.00011). Immunosuppressive treatments did not impact the antibody response or levels in patients with a history of COVID-19 infection or positive anti-nucleocapsid serology.

Conclusions

In Inflammatory Bowel Disease, prior COVID-19 infection or positive anti-nucleocapsid serology leads to increased anti-SARS-CoV-2 spike-specific IgG levels after vaccination, regardless of immunosuppressive treatments. This emphasizes the significance of accounting for previous infection in vaccination approaches.

Identification of potential vaccine targets for elicitation of host immune cells against SARS-CoV-2 by reverse vaccinology approach

The COVID-19 pandemic has emerged as a critical global health crisis, demanding urgent and effective strategies for containment. While some knowledge exists about epitope sequences recognized by human immune cells and their activation of CD8+ T cells within the HLA context, comprehensive information remains limited. This study employs reverse vaccinology to explore antigenic HLA-restricted T-cell epitopes capable of eliciting durable immunity. Screening reveals 187 consensus epitopes, with 23 offering broad population coverage worldwide, spanning over 5000 HLA alleles. Sequence alignment analysis highlights the genetic distinctiveness of these peptides from Homo sapiens and their intermediate to high TAP binding efficiency. Notably, these epitopes share 100 % sequence identity across strains from nine countries, indicating potential for a uniform protective immune response among diverse ethnic populations. Docking simulations further confirm their binding capacity with the HLA allele, validating them as promising targets for SARS-CoV-2 immune recognition. The anticipated epitopes are connected with suitable linkers and adjuvant, and then assessed for its translational efficacy within a bacterial expression vector through computational cloning. Through docking, it is observed that the chimeric vaccine construct forms lasting hydrogen bonds with Toll-like receptor (TLR4), while immune simulation illustrates an increased cytotoxic response aimed at CD8+ T cells. This comprehensive computational analysis suggests the chimeric vaccine construct's potential to provoke a robust immune response against SARS-CoV-2. By delineating these antigenic fragments, our study offers valuable insights into effective vaccine and immunotherapy development against COVID-19, contributing significantly to global efforts in combating this infectious threat.

Alterations in microbiota of patients with COVID-19: implications for therapeutic interventions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently caused a global pandemic, resulting in more than 702 million people being infected and over 6.9 million deaths. Patients with coronavirus disease (COVID-19) may suffer from diarrhea, sleep disorders, depression, and even cognitive impairment, which is associated with long COVID during recovery. However, there remains no consensus on effective treatment methods. Studies have found that patients with COVID-19 have alterations in microbiota and their metabolites, particularly in the gut, which may be involved in the regulation of immune responses. Consumption of probiotics may alleviate the discomfort caused by inflammation and oxidative stress. However, the pathophysiological process underlying the alleviation of COVID-19-related symptoms and complications by targeting the microbiota remains unclear. In the current study, we summarize the latest research and evidence on the COVID-19 pandemic, together with symptoms of SARS-CoV-2 and vaccine use, with a focus on the relationship between microbiota alterations and COVID-19-related symptoms and vaccine use. This work provides evidence that probiotic-based interventions may improve COVID-19 symptoms by regulating gut microbiota and systemic immunity. Probiotics may also be used as adjuvants to improve vaccine efficacy.

Current Progress, Challenges and Prospects in the Development of COVID-19 Vaccines

The COVID-19 pandemic has resulted in over 772 million confirmed cases, including nearly 7 million deaths, according to the World Health Organization (WHO). Leveraging rapid development, accelerated vaccine approval processes, and large-scale production of various COVID-19 vaccines using different technical platforms, the WHO declared an end to the global health emergency of COVID-19 on May 5, 2023. Current COVID-19 vaccines encompass inactivated, live attenuated, viral vector, protein subunit, nucleic acid (DNA and RNA), and virus-like particle (VLP) vaccines. However, the efficacy of these vaccines is diminishing due to the constant mutation of SARS-CoV-2 and the heightened immune evasion abilities of emerging variants. This review examines the impact of the COVID-19 pandemic, the biological characteristics of the virus, and its diverse variants. Moreover, the review underscores the effectiveness, advantages, and disadvantages of authorized COVID-19 vaccines. Additionally, it analyzes the challenges, strategies, and future prospects of developing a safe, broad-spectrum vaccine that confers sufficient and sustainable immune protection against new variants of SARS-CoV-2. These discussions not only offer insight for the development of next-generation COVID-19 vaccines but also summarize experiences for combating future emerging viruses.

Comparative Study of T-Cell Repertoires after COVID-19 Immunization with Homologous or Heterologous Vaccine Booster

Sequencing of the T-cell repertoire is an innovative method to assess the cellular responses after immunization. The purpose of this study was to compare T-cell repertoires after COVID-19 immunization with homologous (HOB) and heterologous (HEB) boosting. The study included 20 participants with a median age of 27.5 (IQR:23) years, who were vaccinated with one dose of the Ad26.COV2.S vaccine and were boosted with either Ad26.COV2.S (n = 10) or BNT162b2 (n = 10) vaccine. Analysis of the T-cell receptor beta locus (TCRβ) sequencing one month after the booster dose identified that the HEB compared to the HOB group exhibited a higher number of both total and COVID-19-related functional T-cell rearrangements [mean of total productive rearrangements (TPRs): 63151.8 (SD ± 18441.5) vs. 34915.4 (SD ± 11121.6), p = 0.001 and COVID-19-TPRs: 522.5 (SD ± 178.0) vs. 298.3 (SD ± 101.1), p = 0.003]. A comparison between the HOB and HEB groups detected no statistically significant differences regarding T-cell Simpson clonality [0.021 (IQR:0.014) vs. 0.019 (IQR:0.007)], richness [8734.5 (IQR:973.3) vs. 8724 (IQR:383.7)] and T-cell fraction [0.19 (IQR:0.08) vs. 0.18 (IQR:0.08)]. HEB also exhibited a substantially elevated humoral immune response one month after the booster dose compared to HOB [median antibody titer (IQR): 10115.0 U/mL (6993.0) vs. 1781.0 U/mL (1314.0), p = 0.001]. T-cell repertoire sequencing indicated that HEB had increased SARS-CoV-2-related T-cell rearrangements, which was in accordance with higher humoral responses and possibly conferring longer protection. Data from the present study indicate that the administration of different COVID-19 vaccines as a booster may provide better protection.

Therapeutic development targeting host heparan sulfate proteoglycan in SARS-CoV-2 infection

The global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to an urgent need for effective therapeutic options. SARS-CoV-2 is a novel coronavirus responsible for the COVID-19 pandemic that has resulted in significant morbidity and mortality worldwide. The virus is known to enter host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor, and emerging evidence suggests that heparan sulfate proteoglycans (HSPGs) play a crucial role in facilitating this process. HSPGs are abundant cell surface proteoglycan present in many tissues, including the lung, and have been shown to interact directly with the spike protein of SARS-CoV-2. This review aims to summarize the current understanding of the role of HSPGs in SARS-CoV-2 infection and the potential of developing new therapies targeting HSPGs.

Predicting Vaccine Effectiveness for Hospitalization and Symptomatic Disease for Novel SARS-CoV-2 Variants Using Neutralizing Antibody Titers

The emergence of new virus variants, including the Omicron variant (B.1.1.529) of SARS-CoV-2, can lead to reduced vaccine effectiveness (VE) and the need for new vaccines or vaccine doses if the extent of immune evasion is severe. Neutralizing antibody titers have been shown to be a correlate of protection for SARS-CoV-2 and other pathogens, and could be used to quickly estimate vaccine effectiveness for new variants. However, no model currently exists to provide precise VE estimates for a new variant against severe disease for SARS-CoV-2 using robust datasets from several populations. We developed predictive models for VE against COVID-19 symptomatic disease and hospitalization across a 54-fold range of mean neutralizing antibody titers. For two mRNA vaccines (mRNA-1273, BNT162b2), models fit without Omicron data predicted that infection with the BA.1 Omicron variant increased the risk of hospitalization 2.8-4.4-fold and increased the risk of symptomatic disease 1.7-4.2-fold compared to the Delta variant. Out-of-sample validation showed that model predictions were accurate; all predictions were within 10% of observed VE estimates and fell within the model prediction intervals. Predictive models using neutralizing antibody titers can provide rapid VE estimates, which can inform vaccine booster timing, vaccine design, and vaccine selection for new virus variants.

Structural insights into the interaction between adenovirus C5 hexon and human lactoferrin

Adenovirus (AdV) infection of the respiratory epithelium is common but poorly understood. Human AdV species C types, such as HAdV-C5, utilize the Coxsackie-adenovirus receptor (CAR) for attachment and subsequently integrins for entry. CAR and integrins are however located deep within the tight junctions in the mucosa where they would not be easily accessible. Recently, a model for CAR-independent AdV entry was proposed. In this model, human lactoferrin (hLF), an innate immune protein, aids the viral uptake into epithelial cells by mediating interactions between the major capsid protein, hexon, and yet unknown host cellular receptor(s). However, a detailed understanding of the molecular interactions driving this mechanism is lacking. Here, we present a new cryo-EM structure of HAdV-5C hexon at high resolution alongside a hybrid structure of HAdV-5C hexon complexed with human lactoferrin (hLF). These structures reveal the molecular determinants of the interaction between hLF and HAdV-C5 hexon. hLF engages hexon primarily via its N-terminal lactoferricin (Lfcin) region, interacting with hexon's hypervariable region 1 (HVR-1). Mutational analyses pinpoint critical Lfcin contacts and also identify additional regions within hLF that critically contribute to hexon binding. Our study sheds more light on the intricate mechanism by which HAdV-C5 utilizes soluble hLF/Lfcin for cellular entry. These findings hold promise for advancing gene therapy applications and inform vaccine development.

IMPORTANCE

Our study delves into the structural aspects of adenovirus (AdV) infections, specifically HAdV-C5 in the respiratory epithelium. It uncovers the molecular details of a novel pathway where human lactoferrin (hLF) interacts with the major capsid protein, hexon, facilitating viral entry, and bypassing traditional receptors such as CAR and integrins. The study's cryo-EM structures reveal how hLF engages hexon, primarily through its N-terminal lactoferricin (Lfcin) region and hexon's hypervariable region 1 (HVR-1). Mutational analyses identify critical Lfcin contacts and other regions within hLF vital for hexon binding. This structural insight sheds light on HAdV-C5's mechanism of utilizing soluble hLF/Lfcin for cellular entry, holding promise for gene therapy and vaccine development advancements in adenovirus research.

Self-Amplifying RNA: A Second Revolution of mRNA Vaccines against COVID-19

SARS-CoV-2 virus, the causative agent of COVID-19, has produced the largest pandemic in the 21st century, becoming a very serious health problem worldwide. To prevent COVID-19 disease and infection, a large number of vaccines have been developed and approved in record time, including new vaccines based on mRNA encapsulated in lipid nanoparticles. While mRNA-based vaccines have proven to be safe and effective, they are more expensive to produce compared to conventional vaccines. A special type of mRNA vaccine is based on self-amplifying RNA (saRNA) derived from the genome of RNA viruses, mainly alphaviruses. These saRNAs encode a viral replicase in addition to the antigen, usually the SARS-CoV-2 spike protein. The replicase can amplify the saRNA in transfected cells, potentially reducing the amount of RNA needed for vaccination and promoting interferon I responses that can enhance adaptive immunity. Preclinical studies with saRNA-based COVID-19 vaccines in diverse animal models have demonstrated the induction of robust protective immune responses, similar to conventional mRNA but at lower doses. Initial clinical trials have confirmed the safety and immunogenicity of saRNA-based vaccines in individuals that had previously received authorized COVID-19 vaccines. These findings have led to the recent approval of two of these vaccines by the national drug agencies of India and Japan, underscoring the promising potential of this technology.

Expanded specific T cells to hypomutated regions of the SARS-CoV-2 using mRNA electroporated antigen-presenting cells

The COVID-19 pandemic has caused about seven million deaths worldwide. Preventative vaccines have been developed including Spike gp mRNA-based vaccines that provide protection to immunocompetent patients. However, patients with primary immunodeficiencies, patients with cancer, or hematopoietic stem cell transplant recipients are not able to mount robust immune responses against current vaccine approaches. We propose to target structural SARS-CoV-2 antigens (i.e., Spike gp, Membrane, Nucleocapsid, and Envelope) using circulating human antigen-presenting cells electroporated with full length SARS-CoV-2 structural protein-encoding mRNAs to activate and expand specific T cells. Based on the Th1-type cytokine and cytolytic enzyme secretion upon antigen rechallenge, we were able to generate SARS-CoV-2 specific T cells in up to 70% of unexposed unvaccinated healthy donors (HDs) after 3 subsequent stimulations and in 100% of recovered patients (RPs) after 2 stimulations. By means of SARS-CoV-2 specific TCRβ repertoire analysis, T cells specific to Spike gp-derived hypomutated regions were identified in HDs and RPs despite viral genomic evolution. Hence, we demonstrated that SARS-CoV-2 mRNA-loaded antigen-presenting cells are effective activating and expanding COVID19-specific T cells. This approach represents an alternative to patients who are not able to mount adaptive immune responses to current COVID-19 vaccines with potential protection across new variants that have conserved genetic regions.

Quantifying how single dose Ad26.COV2.S vaccine efficacy depends on Spike sequence features

In the ENSEMBLE randomized, placebo-controlled phase 3 trial (NCT04505722), estimated single-dose Ad26.COV2.S vaccine efficacy (VE) was 56% against moderate to severe-critical COVID-19. SARS-CoV-2 Spike sequences were determined from 484 vaccine and 1,067 placebo recipients who acquired COVID-19. In this set of prespecified analyses, we show that in Latin America, VE was significantly lower against Lambda vs. Reference and against Lambda vs. non-Lambda [family-wise error rate (FWER) p < 0.05]. VE differed by residue match vs. mismatch to the vaccine-insert at 16 amino acid positions (4 FWER p < 0.05; 12 q-value ≤ 0.20); significantly decreased with physicochemical-weighted Hamming distance to the vaccine-strain sequence for Spike, receptor-binding domain, N-terminal domain, and S1 (FWER p < 0.001); differed (FWER ≤ 0.05) by distance to the vaccine strain measured by 9 antibody-epitope escape scores and 4 NTD neutralization-impacting features; and decreased (p = 0.011) with neutralization resistance level to vaccinee sera. VE against severe-critical COVID-19 was stable across most sequence features but lower against the most distant viruses.

Engineering Self-Assembling Peptide Hydrogel to Enhance the Capacity of Dendritic Cells to Activate In Vivo T-Cell Immunity

The efficacy of the dendritic cell (DC) has failed to meet expectations thus far, and crucial problems such as the immature state of DCs, low targeting efficiency, insufficient number of dendritic cells, and microenvironment are still the current focus. To address these problems, we developed two self-assembling peptides, RLDI and RQDT, that mimic extracellular matrix (ECM). These peptides can be self-assembled into highly ordered three-dimensional nanofiber scaffold structures, where RLDI can form gelation immediately. In addition, we found that RLDI and RQDT enhance the biological function of DCs, including releasing antigens sustainably, adhering to DCs, promoting the maturation of DCs, and increasing the ability of DC antigen presentation. Moreover, peptide hydrogel-based DC treatment significantly achieved prophylactic and treatment effects on colon cancer. These results have certain implications for the design of new broad-spectrum vaccines in the future.

Global Prevalence of Preexisting Antibodies against Human Adenoviruses, Surveyed from 1962 to 2021

BACKGROUND

Human adenoviruses (HAdVs) are extensively used as vectors for vaccines development and cancer therapy. People who already have antibodies against HAdVs, on the other hand, would have an impact on the preventative or therapeutic effect. This review focuses primarily on the prevalence of pre-existing antibodies against HAdVs in distinct geographical populations.

SUMMARY

After screening, 64 studies from 31 countries between 1962 and 2021 were selected, totaling 39,427 samples. The total prevalence of preexisting antibodies to HAdVs varied by country or location, ranging from 2.00 to 95.70%. Southeast Asia had the highest prevalence (54.57%) while Europe had the lowest (18.17%). The prevalence in practically all developing nations was higher than in developed nations. Adults have a greater frequency than children and newborns in most nations. The primary HAdV antibody types varied by country. Adults in China, the USA, the United Kingdom, and Belgium had the lowest prevalence of preexisting antibodies against HAdV55, HAdV37, HAdV8, and HAdV36, respectively. Children in the USA, China, the United Kingdom, and Japan had the lowest rates of HAdV48, HAdV11, HAdV8, and HAdV40. The frequency of antibodies differed significantly between military and civilian groups.

KEY MESSAGES

Preexisting antibodies against various types of HAdVs differed greatly throughout worldwide populations. Future development of HAdV-vector vaccines and medicines should focus on preexisting antibodies in target groups rather than a "one-size-fits-all" strategy. It might be advantageous in selecting HAdV vectors for studying the prevalence of preexisting antibodies against HAdVs in different locations and people throughout the world.

Safety and immunogenicity of the NVX-CoV2373 vaccine as a booster in adults previously vaccinated with the BBIBP-CorV vaccine

This phase 3 observer-blind, randomized, controlled study was conducted in adults ≥18 years of age to assess the safety and immunogenicity of NVX-CoV2373 as a heterologous booster compared to BBIBP-CorV when utilized as a homologous booster. Approximately 1000 participants were randomly assigned in a 1:1 ratio to receive a single dose of NVX-CoV2373 or BBIBP-CorV after prior vaccination with 2 or 3 doses of BBIBP-CorV. Solicited adverse events (AEs) were collected for 7 days after vaccination. Unsolicited AEs were collected for 28 days following the booster dose and serious adverse and adverse events of special interest (AESI) were collected throughout the study. Anti-spike IgG and neutralizing antibodies against SARS-CoV-2 were measured at baseline, day 14, day 28, and day 180. The study achieved its primary non-inferiority endpoint and also demonstrated statistically higher neutralization responses when NVX-CoV2373 was utilized as a heterologous booster compared with BBIBP-CorV as a homologous booster. Both vaccines had an acceptably low reactogenicity profile, and no new safety concerns were found. Heterologous boosting with NVX-CoV2373 was a highly immunogenic and safe vaccine regimen in those previously vaccinated with BBIBP-CorV.

Ongoing evolution of SARS-CoV-2 drives escape from mRNA vaccine-induced humoral immunity

Since the COVID-19 pandemic began in 2020, viral sequencing has documented 131 individual mutations in the viral spike protein across 48 named variants. To determine the ability of vaccine-mediated humoral immunity to keep pace with continued SARS-CoV-2 evolution, we assessed the neutralization potency of sera from 76 vaccine recipients collected after 2 to 6 immunizations against a comprehensive panel of mutations observed during the pandemic. Remarkably, while many individual mutations that emerged between 2020 and 2022 exhibit escape from sera following primary vaccination, few escape boosted sera. However, progressive loss of neutralization was observed across newer variants, irrespective of vaccine doses. Importantly, an updated XBB.1.5 booster significantly increased titers against newer variants but not JN.1. These findings demonstrate that seasonal boosters improve titers against contemporaneous strains, but novel variants continue to evade updated mRNA vaccines, demonstrating the need for novel approaches to adequately control SARS-CoV-2 transmission.

The ethics of clinical research in the era of COVID-19

There is an urgent need for increased understanding of COVID-19 and strategies for its prevention, treatment, and mitigation. All participants in the research enterprise, including institutional review boards, have an ethical duty to protect participants and ensure that the benefits gained from such research do not conflict with the core principles that guided researchers prior to the pandemic. In this review, we discuss the ethical issues surrounding initiation and conduct of clinical trials, focusing on novel COVID-19 therapeutic, vaccine, or biospecimen research, using the principles of autonomy, beneficence, and justice. We discuss strategies to manage the practical challenges associated with the conduct of clinical trials, with an emphasis on maintaining the rights and welfare of research participants.

A register and questionnaire study of long-term general health symptoms following SARS-CoV-2 vaccination in Denmark

Many individuals who refuse COVID-19 vaccination have concerns about long-term side effects. Here, we report findings on self-reported symptoms from a Danish survey- and register study. The study included 34,868 vaccinated primary course recipients, 95.8% of whom received mRNA vaccines, and 1,568 unvaccinated individuals. Participants had no known history of SARS-CoV-2 infection. Using g-computation on logistic regression, risk differences (RDs) for symptoms between vaccinated and unvaccinated persons were estimated with adjustments for possible confounders. Within six weeks after vaccination, higher risks were observed for physical exhaustion (RD 4.9%, 95% CI 1.1% to 8.4%), fever or chills (RD 4.4%, 95% CI 2.1% to 6.7%), and muscle/joint pain (RD 7.0%, 95% CI 3.1% to 10.7%), compared to unvaccinated individuals. Beyond twenty-six weeks, risks were higher among the vaccinated for sleeping problems (RD 3.0, 95% 0.2 to 5.8), fever or chills (RD 2.0, 95% CI 0.4 to 3.6), reduced/altered taste (RD 1.2, 95% CI 0.2 to 2.3) and shortness of breath (RD 2.6, 95% CI 0.9 to 4.0). However, when examining pre-omicron responses only, the difference for reduced/altered taste was significant. As expected, the risk of experiencing physical exhaustion, fever or chills, and muscle/joint pain was higher among persons who responded within six weeks of completing the primary course. No significant differences were observed for the 7-25-week period after vaccination. Associations for the period beyond 26 weeks must be interpreted with caution and in the context of undetected SARS-CoV-2 infection, wide confidence intervals, and multiple testing. Overall, we observe no concerning signs of long-term self-reported physical, cognitive, or fatigue symptoms after vaccination.

Nanotechnology of inhalable vaccines for enhancing mucosal immunity

Vaccines are the cornerstone of world health. The majority of vaccines are formulated as injectable products, facing the drawbacks of cold chain transportation, needle-stick injuries, and primary systemic immunity. Inhalable vaccines exhibited unique advantages due to their small dose, easy to use, quick effect, and simultaneous induction of mucosal and systemic responses. Facing global pandemics, especially the coronavirus disease 2019 (COVID-19), a majority of inhalable vaccines are in preclinical or clinical trials. A better understanding of advanced delivery technologies of inhalable vaccines may provide new scientific insights for developing inhalable vaccines. In this review article, detailed immune mechanisms involving mucosal, cellular, and humoral immunity were described. The preparation methods of inhalable vaccines were then introduced. Advanced nanotechnologies of inhalable vaccines containing inhalable nucleic acid vaccines, inhalable adenovirus vector vaccines, novel adjuvant-assisted inhalable vaccines, and biomaterials for inhalable vaccine delivery were emphatically discussed. Meanwhile, the latest clinical progress in inhalable vaccines for COVID-19 and tuberculosis was discussed.

Inactivated whole virion vaccine protects K18-hACE2 Tg mice against the Omicron SARS-CoV-2 variant via cross-reactive T cells and nonneutralizing antibody responses

COVID-19 is a systemic inflammatory disease initiated by SARS-CoV-2 virus infection. Multiple vaccines against the Wuhan variant of SARS-CoV-2 have been developed including a whole virion beta-propiolactone-inactivated vaccine based on the B.1.1 strain (CoviVac). Since most of the population has been vaccinated by targeting the original or early variants of SARS-CoV-2, the emergence of novel mutant variants raises concern over possible evasion of vaccine-induced immune responses. Here, we report on the mechanism of protection by CoviVac, a whole virion-based vaccine, against the Omicron variant. CoviVac-immunized K18-hACE2 Tg mice were protected against both prototype B.1.1 and BA.1-like (Omicron) variants. Subsequently, vaccinated K18-hACE2 Tg mice rapidly cleared the infection via cross-reactive T-cell responses and cross-reactive, non-neutralizing antibodies recognizing the Omicron variant Spike protein. Thus, our data indicate that efficient protection from SARS-CoV-2 variants can be achieved by the orchestrated action of cross-reactive T cells and non-neutralizing antibodies.

SARS-CoV-2 Vaccine-Elicited Immunity after B Cell Depletion in Multiple Sclerosis

The impact of B cell deficiency on the humoral and cellular responses to SARS-CoV2 mRNA vaccination remains a challenging and significant clinical management question. We evaluated vaccine-elicited serological and cellular responses in 1) healthy individuals who were pre-exposed to SARS-CoV-2 (n = 21), 2) healthy individuals who received a homologous booster (mRNA, n = 19; or Novavax, n = 19), and 3) persons with multiple sclerosis on B cell depletion therapy (MS-αCD20) receiving mRNA homologous boosting (n = 36). Pre-exposure increased humoral and CD4 T cellular responses in immunocompetent individuals. Novavax homologous boosting induced a significantly more robust serological response than mRNA boosting. MS-α CD20 had an intact IgA mucosal response and an enhanced CD8 T cell response to mRNA boosting compared with immunocompetent individuals. This enhanced cellular response was characterized by the expansion of only effector, not memory, T cells. The enhancement of CD8 T cells in the setting of B cell depletion suggests a regulatory mechanism between B and CD8 T cell vaccine responses.

Bondzie E, Fisher JL, Mazurek CR, Patio RC, Rodrigues SL, Rowe M, Surve N, Ty DM, Wu C, Chicz TM, Tong X, Korber B, McNamara RP, Barouch DH. Waning immunity and IgG4 responses following bivalent mRNA boosting

Messenger RNA (mRNA) vaccines were highly effective against the ancestral SARS-CoV-2 strain, but the efficacy of bivalent mRNA boosters against XBB variants was substantially lower. Here, we show limited durability of neutralizing antibody (NAb) responses against XBB variants and isotype switching to immunoglobulin G4 (IgG4) responses following bivalent mRNA boosting. Bivalent mRNA boosting elicited modest XBB.1-, XBB.1.5-, and XBB.1.16-specific NAbs that waned rapidly within 3 months. In contrast, bivalent mRNA boosting induced more robust and sustained NAbs against the ancestral WA1/2020 strain, suggesting immune imprinting. Following bivalent mRNA boosting, serum antibody responses were primarily IgG2 and IgG4 responses with poor Fc functional activity. In contrast, a third monovalent mRNA immunization boosted all isotypes including IgG1 and IgG3 with robust Fc functional activity. These data show substantial immune imprinting for the ancestral spike and isotype switching to IgG4 responses following bivalent mRNA boosting, with important implications for future booster designs and boosting strategies.

Targeting the Main Protease (Mpro, nsp5) by Growth of Fragment Scaffolds Exploiting Structure-Based Methodologies

The main protease Mpro, nsp5, of SARS-CoV-2 (SCoV2) is one of its most attractive drug targets. Here, we report primary screening data using nuclear magnetic resonance spectroscopy (NMR) of four different libraries and detailed follow-up synthesis on the promising uracil-containing fragment Z604 derived from these libraries. Z604 shows time-dependent binding. Its inhibitory effect is sensitive to reducing conditions. Starting with Z604, we synthesized and characterized 13 compounds designed by fragment growth strategies. Each compound was characterized by NMR and/or activity assays to investigate their interaction with Mpro. These investigations resulted in the four-armed compound 35b that binds directly to Mpro. 35b could be cocrystallized with Mpro revealing its noncovalent binding mode, which fills all four active site subpockets. Herein, we describe the NMR-derived fragment-to-hit pipeline and its application for the development of promising starting points for inhibitors of the main protease of SCoV2.

Broad protection against clade 1 sarbecoviruses after a single immunization with cocktail spike-protein-nanoparticle vaccine

The 2002 SARS outbreak, the 2019 emergence of COVID-19, and the continuing evolution of immune-evading SARS-CoV-2 variants together highlight the need for a broadly protective vaccine against ACE2-utilizing sarbecoviruses. While updated variant-matched formulations are a step in the right direction, protection needs to extend beyond SARS-CoV-2 and its variants to include SARS-like viruses. Here, we introduce bivalent and trivalent vaccine formulations using our spike protein nanoparticle platform that completely protect female hamsters against BA.5 and XBB.1 challenges with no detectable virus in the lungs. The trivalent cocktails elicit highly neutralizing responses against all tested Omicron variants and the bat sarbecoviruses SHC014 and WIV1. Finally, our 614D/SHC014/XBB trivalent spike formulation completely protects human ACE2-transgenic female hamsters against challenges with WIV1 and SHC014 with no detectable virus in the lungs. Collectively, these results illustrate that our trivalent protein-nanoparticle cocktail can provide broad protection against SARS-CoV-2-like and SARS-CoV-1-like sarbecoviruses.

Assessment of adverse events among healthcare workers following the Janssen COVID-19 vaccine in Tigray, Ethiopia

Apart from the inequality in vaccination, war zones and areas where communication is disrupted are affected by myths and misconceptions about COVID-19 vaccines, heightening vaccine hesitancy. Local data on adverse events of the vaccines and their mildness can increase confidence and acceptance of the vaccines in the respective population. In areas of conflict and communication blackouts, the perception of the vaccines by health workers is of paramount importance as public health recommendations may not reach the public. Therefore, the scientific evaluation of adverse events following COVID-19 vaccination in such areas is invaluable. This cross-sectional, facility-based study was conducted using a structured, interviewer-administered questionnaire to assess the adverse events experienced by healthcare workers who received the Janssen COVID-19 vaccine. The sample was divided proportionally to the number of vaccinated healthcare workers for the different healthcare professions, and participants were then randomly selected from each profession. Prior to data collection, a pilot test was conducted with 5% of the sample size outside the selected hospital. The study was conducted using a structured questionnaire completed by an interviewer to assess adverse events in 442 healthcare workers who had received the Janssen COVID-19 vaccine between July 11 and 25, 2022. The study period was from August 15 to September 15, 2022. A significant number of healthcare workers [366 (83.3%); 95% CI 79.5%, 86.5%] experienced at least one adverse event. Nearly 90% of participants reported that the adverse events were mild to moderate. Pain at the injection site [307 (69.5%); 95% CI 65.0%, 73.6%] and headache [247 (55.9%); 95% CI 51.2%, 60.4%] were the most common local and systemic adverse events, respectively. Two HCWs experienced anaphylactic reaction. Younger age was significantly associated with the occurrence of adverse events. We deciphered that the adverse events reported by the study participants were not different from the typically occurring vaccine-related adverse reactions, and therefore concluded that post-vaccination reactions in healthcare workers were minor. Although vaccination in Tigray is currently stalled due to the siege, responsible stakeholders should develop a mechanism to track population-wide adverse events once the vaccines start to rollout.

A review on Zika vaccine development

Zika virus (ZIKV), which belongs to the Flavivirus family, is mainly transmitted via the bite of Aedes mosquitoes. In newborns, ZIKV infection can cause severe symptoms such as microcephaly, while in adults, it can lead to Guillain‒Barré syndrome (GBS). Due to the lack of specific therapeutic methods against ZIKV, the development of a safe and effective vaccine is extremely important. Several potential ZIKV vaccines, such as live attenuated, inactivated, nucleic acid, viral vector, and recombinant subunit vaccines, have demonstrated promising outcomes in clinical trials involving human participants. Therefore, in this review, the recent developmental progress, advantages and disadvantages of these five vaccine types are examined, and practical recommendations for future development are provided.

Enhancing Immunological Memory: Unveiling Booster Doses to Bolster Vaccine Efficacy Against Evolving SARS-CoV-2 Mutant Variants

A growing number of re-infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in previously immunized individuals has sparked discussions about the potential need for a booster vaccine dosage to counteract declining antibody levels and new strains. The protective immunity produced by vaccinations, and past illnesses relies on immunological memory. CD4 + T cells, CD8 + T cells, B cells, and long-lasting antibody responses are all components of the adaptive immune system that can generate and maintain this immunological memory. Since novel mutant variants have emerged one after the other, the world has been hit by repeated waves. Various vaccine formulations against SARS-CoV-2 have been administered across the globe. Thus, estimating the efficacy of those vaccines against gradually developed mutant stains is the essential parameter regarding the fate of those vaccine formulations and the necessity of booster doses and their frequency. In this review, focus has also been given to how vaccination stacks up against moderate and severe acute infections in terms of the longevity of the immune cells, neutralizing antibody responses, etc. However, hybrid immunity shows a greater accuracy of re-infection of variants of concern (VOCs) of SARS-CoV-2 than infection and immunization. The review conveys knowledge of detailed information about several marketed vaccines and the status of their efficacy against specific mutant strains of SARS-CoV-2. Furthermore, this review discusses the status of immunological memory after infection, mixed infection, and vaccination.

SARS-CoV-2 vaccination may mitigate dysregulation of IL-1/IL-18 and gastrointestinal symptoms of the post-COVID-19 condition

The rapid development of safe and effective vaccines helped to prevent severe disease courses after SARS-CoV-2 infection and to mitigate the progression of the COVID-19 pandemic. While there is evidence that vaccination may reduce the risk of developing post-COVID-19 conditions (PCC), this effect may depend on the viral variant. Therapeutic effects of post-infection vaccination have been discussed but the data for individuals with PCC remains inconclusive. In addition, extremely rare side effects after SARS-CoV-2 vaccination may resemble the heterogeneous PCC phenotype. Here, we analyze the plasma levels of 25 cytokines and SARS-CoV-2 directed antibodies in 540 individuals with or without PCC relative to one or two mRNA-based COVID-19 vaccinations as well as in 20 uninfected individuals one month after their initial mRNA-based COVID-19 vaccination. While none of the SARS-CoV-2 naïve individuals reported any persisting sequelae or exhibited PCC-like dysregulation of plasma cytokines, we detected lower levels of IL-1β and IL-18 in patients with ongoing PCC who received one or two vaccinations at a median of six months after infection as compared to unvaccinated PCC patients. This reduction correlated with less frequent reporting of persisting gastrointestinal symptoms. These data suggest that post-infection vaccination in patients with PCC might be beneficial in a subgroup of individuals displaying gastrointestinal symptoms.

Long-term efficacy of the peptide-based COVID-19 T cell activator CoVac-1 in healthy adults

OBJECTIVES

T cell immunity is key for the control of viral infections including SARS-CoV-2, in particular with regard to immune memory and protection against arising genetic variants.

METHODS

We recently evaluated a peptide-based SARS-CoV-2 T cell activator termed CoVac-1 in a first-in-human trial in healthy adults. Here, we report on long-term safety and efficacy data of CoVac-1 until month 12.

RESULTS

CoVac-1 is well tolerated without long-term immune-related side effects and induces long-lasting anti-viral T cell responses in 100% of study participants, with potent expandability of clusters of differentiation (CD4+) and CD8+ T cells targeting multiple different CoVac-1 T cell epitopes. T cell responses were associated with stronger injection site reaction. Beyond induction of T cell immunity, 89% of subjects developed CoVac-1-specific immunoglobulin G antibodies which associated with the intensity of the T cell response, indicating that CoVac-1-specific CD4+ T cells support the induction of B-cell responses. Vaccination with approved COVID-19 vaccines boosted CoVac-1-specific T cell responses. Overall, a low SARS-CoV-2 infection rate (8.3%) was observed.

CONCLUSION

Together, a single application of CoVac-1 elicits long-lived and broad SARS-CoV-2-specific T cell immunity, which further supports the current evaluation of our T cell activator in patients with congenital or acquired B-cell defects.

Vaccine-carditis study: Spanish multicenter registry of inflammatory heart disease after COVID-19 vaccination

INTRODUCTION AND OBJECTIVES

Vaccines against SARS-CoV-2 have been a major scientific and medical achievement in the control of the COVID-19 pandemic. However, very infrequent cases of inflammatory heart disease have been described as adverse events, leading to uncertainty in the scientific community and in the general population.

METHODS

The Vaccine-Carditis Registry has included all cases of myocarditis and pericarditis diagnosed within 30 days after COVID-19 vaccination since August 1, 2021 in 29 centers throughout the Spanish territory. The definitions of myocarditis (probable or confirmed) and pericarditis followed the consensus of the Centers for Disease Control and the Clinical Practice Guidelines of the European Society of Cardiology. A comprehensive analysis of clinical characteristics and 3-month evolution is presented.

RESULTS

From August 1, 2021, to March 10, 2022, 139 cases of myocarditis or pericarditis were recorded (81.3% male, median age 28 years). Most cases were detected in the 1st week after administration of an mRNA vaccine, the majority after the second dose. The most common presentation was mixed inflammatory disease (myocarditis and pericarditis). 11% had left ventricular systolic dysfunction, 4% had right ventricular systolic dysfunction, and 21% had pericardial effusion. In cardiac magnetic resonance studies, left ventricular inferolateral involvement was the most frequent pattern (58%). More than 90% of cases had a benign clinical course. After a 3-month follow-up, the incidence of adverse events was 12.78% (1.44% mortality).

CONCLUSIONS

In our setting, inflammatory heart disease after vaccination against SARS-CoV-2 predominantly affects young men in the 1st week after the second dose of RNA-m vaccine and presents a favorable clinical course in most cases.

To be remembered: B cell memory response against SARS-CoV-2 and its variants in vaccinated and unvaccinated individuals

COVID-19 disease has plagued the world economy and affected the overall well-being and life of most of the people. Natural infection as well as vaccination leads to the development of an immune response against the pathogen. This involves the production of antibodies, which can neutralize the virus during future challenges. In addition, the development of cellular immune memory with memory B and T cells provides long-lasting protection. The longevity of the immune response has been a subject of intensive research in this field. The extent of immunity conferred by different forms of vaccination or natural infections remained debatable for long. Hence, understanding the effectiveness of these responses among different groups of people can assist government organizations in making informed policy decisions. In this article, based on the publicly available data, we have reviewed the memory response generated by some of the vaccines against SARS-CoV-2 and its variants, particularly B cell memory in different groups of individuals.

Development of Adenovirus-Based Covid-19 Vaccine Candidate in Indonesia

Covid-19 pandemic has struck worldwide by end of 2019 and the use of various vaccine platforms was one of the main strategies to end this. To meet the needs for vaccine technology equality among many countries, we developed adenovirus-based Covid-19 vaccine candidate in Indonesia. SARS-CoV-2 Spike gene (S) was constructed into pAdEasy vector. The recombinant serotype 5 Adenovirus (AdV_S) genome was transfected into AD293 cells to produce recombinant adenovirus. Characterization using PCR confirmed the presence of spike gene. Transgene expression analysis showed the expression of S protein in AdV_S infected AD293 and A549 cells. Optimization of viral production showed the highest titer was obtained at MOI of 0.1 and 1 at 4 days. The in vivo study was performed by injecting Balb/c mice with 3.5 × 107 ifu of purified adenovirus. The result showed that S1-specific IgG was increased up to 56 days after single-dose administration of AdV_S. Interestingly, significant increase of S1 glycoprotein-specific IFN-γ ELISpot was observed in AdV_S treated Balb/c mice. In conclusion, the AdV_S vaccine candidate was successfully produced at laboratory scale, immunogenic, and did not cause severe inflammation in Balb/c mice. This study serves as initial step towards manufacturing of adenovirus-based vaccine in Indonesia.

In search of a pan-coronavirus vaccine: next-generation vaccine design and immune mechanisms

Members of the coronaviridae family are endemic to human populations and have caused several epidemics and pandemics in recent history. In this review, we will discuss the feasibility of and progress toward the ultimate goal of creating a pan-coronavirus vaccine that can protect against infection and disease by all members of the coronavirus family. We will detail the unmet clinical need associated with the continued transmission of SARS-CoV-2, MERS-CoV and the four seasonal coronaviruses (HCoV-OC43, NL63, HKU1 and 229E) in humans and the potential for future zoonotic coronaviruses. We will highlight how first-generation SARS-CoV-2 vaccines and natural history studies have greatly increased our understanding of effective antiviral immunity to coronaviruses and have informed next-generation vaccine design. We will then consider the ideal properties of a pan-coronavirus vaccine and propose a blueprint for the type of immunity that may offer cross-protection. Finally, we will describe a subset of the diverse technologies and novel approaches being pursued with the goal of developing broadly or universally protective vaccines for coronaviruses.

Evaluation of the immunoprotective effects of porcine deltacoronavirus subunit vaccines

Porcine deltacoronavirus (PDCoV), a new porcine enteric coronavirus, has seriously endangered the pig breeding industry and caused great economic losses. However, a PDCoV vaccine is not commercially available. Therefore, new and efficient PDCoV vaccines must be developed without delay. In this study, we used the ExpiCHO eukaryotic expression system to express and purify the following 3 structural proteins of PDCoV: S, N and M. Subsequently, the level of humoral and cellular immunity induced by the S protein (immunization with the S protein alone) and a protein mixture (immunization with a mixture of S, N and M proteins) were evaluated in mice and piglets, respectively, and the performances of the 2 immunizations in a challenge protection test were assessed in piglets. The results showed that both the S protein and the protein mixture induced the production of high levels of specific IgG antibodies and neutralizing antibodies and effectively neutralized PDCoV-infected LLC-PK cells in vitro. Furthermore, compared with the S protein, the N and M proteins in the protein mixture promoted the expression of CD8+ T cells and IFN-γ, induced a stronger cellular immune response, and effectively protected 4/5 of the piglets from PDCoV infection. In conclusion, the results of this study showed that the N and M proteins play important roles in inducing an immunoprotective response. Using N and M antigens as effective antigenic components in the development of PDCoV vaccines in the future will effectively increase the immune efficacy of the vaccines.

Silent battles: immune responses in asymptomatic SARS-CoV-2 infection

SARS-CoV-2 infections manifest with a broad spectrum of presentations, ranging from asymptomatic infections to severe pneumonia and fatal outcomes. This review centers on asymptomatic infections, a widely reported phenomenon that has substantially contributed to the rapid spread of the pandemic. In such asymptomatic infections, we focus on the role of innate, humoral, and cellular immunity. Notably, asymptomatic infections are characterized by an early and robust innate immune response, particularly a swift type 1 IFN reaction, alongside a rapid and broad induction of SARS-CoV-2-specific T cells. Often, antibody levels tend to be lower or undetectable after asymptomatic infections, suggesting that the rapid control of viral replication by innate and cellular responses might impede the full triggering of humoral immunity. Even if antibody levels are present in the early convalescent phase, they wane rapidly below serological detection limits, particularly following asymptomatic infection. Consequently, prevalence studies reliant solely on serological assays likely underestimate the extent of community exposure to the virus.

A Practical Update on COVID-19 and Inflammatory Bowel Disease: COVID-19 Disease Risk and Vaccine Safety and Efficacy

The COVID-19 pandemic introduced significant uncertainty regarding the care of patients with inflammatory bowel disease (IBD). Substantial research efforts have made progress in answering many of the questions that arose, but the constantly shifting paradigm of COVID-19-related research and recommendations has made it challenging for IBD clinicians to remain up-to-date. The goal of this article is to provide a concise and practical summary of the literature evaluating COVID-19 disease risk in addition to COVID-19 vaccine safety, immunogenicity, real-world effectiveness, and uptake among patients with IBD.

Mucosal boosting enhances vaccine protection against SARS-CoV-2 in macaques

A limitation of current SARS-CoV-2 vaccines is that they provide minimal protection against infection with current Omicron subvariants1,2, although they still provide protection against severe disease. Enhanced mucosal immunity may be required to block infection and onward transmission. Intranasal administration of current vaccines has proven inconsistent3-7, suggesting that alternative immunization strategies may be required. Here we show that intratracheal boosting with a bivalent Ad26-based SARS-CoV-2 vaccine results in substantial induction of mucosal humoral and cellular immunity and near-complete protection against SARS-CoV-2 BQ.1.1 challenge. A total of 40 previously immunized rhesus macaques were boosted with a bivalent Ad26 vaccine by the intramuscular, intranasal and intratracheal routes, or with a bivalent mRNA vaccine by the intranasal route. Ad26 boosting by the intratracheal route led to a substantial expansion of mucosal neutralizing antibodies, IgG and IgA binding antibodies, and CD8+ and CD4+ T cell responses, which exceeded those induced by Ad26 boosting by the intramuscular and intranasal routes. Intratracheal Ad26 boosting also led to robust upregulation of cytokine, natural killer, and T and B cell pathways in the lungs. After challenge with a high dose of SARS-CoV-2 BQ.1.1, intratracheal Ad26 boosting provided near-complete protection, whereas the other boosting strategies proved less effective. Protective efficacy correlated best with mucosal humoral and cellular immune responses. These data demonstrate that these immunization strategies induce robust mucosal immunity, suggesting the feasibility of developing vaccines that block respiratory viral infections.

COVID-19 vaccine hesitancy in KwaZulu-Natal, South Africa: A survey of unvaccinated adults

Background

Concerns and misconceptions surrounding coronavirus disease 2019 (COVID-19) vaccines may account for vaccine hesitancy and low uptake.

Aim

To determine prevalence of COVID-19 vaccine hesitancy, vaccine-related misconceptions, and predictors of vaccine hesitancy among South Africans.

Setting

Community setting in five districts in KwaZulu- Natal province.

Methods

Between August 20, 2021, and September 27, 2021, we conducted a cross-sectional survey, interviewing 300 unvaccinated adults amid the national vaccination campaign. Predictors of hesitancy were identified through multivariable logistic regression analysis.

Results

Participants had a median age of 29 years (IQR: 23-39), 86.7% were Black African, 63.2% were male, 53.3% resided in rural communities, and 59.3% (95% CI: 53.8% - 64.9%) were classified as vaccine hesitant. The primary reason for not vaccinating was a lack of trust in the vaccine (62.1%). Factors associated with reduced vaccine hesitancy included age (participants aged 35-49 years: OR: 0.28, 95% CI: 0.18-0.64, p = 0.003; participants over 50 years: OR: 0.18, 95% CI: 0.07-0.47, p = 0.0004), previous COVID-19 infection (OR: 0.31, 95% CI: 0.11-0.87, p = 0.03), and receiving vaccine information from healthcare workers (OR: 0.32, 95% CI: 0.10-1.0, p = 0.05). Unemployed (OR: 2.14, 95% CI: 1.1-4.2, p = 0.03) and self-employed individuals (OR: 2.98, 95% CI: 1.27-7.02, p = 0.01) were more likely to be vaccine hesitant.

Conclusion

COVID-19 vaccine hesitancy rates are high in KwaZulu-Natal. Uptake could be enhanced by healthcare workers leading information campaigns with messages targeting younger individuals, the unemployed, and the self-employed.

Contribution

This survey provides evidence to improve COVID-19 vaccination uptake in South Africa.

B-cell and antibody responses to SARS-CoV-2: infection, vaccination, and hybrid immunity

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019 prompted scientific, medical, and biotech communities to investigate infection- and vaccine-induced immune responses in the context of this pathogen. B-cell and antibody responses are at the center of these investigations, as neutralizing antibodies (nAbs) are an important correlate of protection (COP) from infection and the primary target of SARS-CoV-2 vaccine modalities. In addition to absolute levels, nAb longevity, neutralization breadth, immunoglobulin isotype and subtype composition, and presence at mucosal sites have become important topics for scientists and health policy makers. The recent pandemic was and still is a unique setting in which to study de novo and memory B-cell (MBC) and antibody responses in the dynamic interplay of infection- and vaccine-induced immunity. It also provided an opportunity to explore new vaccine platforms, such as mRNA or adenoviral vector vaccines, in unprecedented cohort sizes. Combined with the technological advances of recent years, this situation has provided detailed mechanistic insights into the development of B-cell and antibody responses but also revealed some unexpected findings. In this review, we summarize the key findings of the last 2.5 years regarding infection- and vaccine-induced B-cell immunity, which we believe are of significant value not only in the context of SARS-CoV-2 but also for future vaccination approaches in endemic and pandemic settings.

Prophylactic HIV-1 vaccine trials: past, present, and future

An effective HIV-1 vaccine is a global health priority but has remained elusive for more than 40 years. Key scientific hurdles that have hampered vaccine development are the unprecedented genetic variability of the virus, the rapid establishment of persistent viral latency, and the challenges associated with induction of broadly neutralising antibodies. Clinical trials have been instrumental in evaluating scientific concepts and testing vaccine strategies. This Review discusses lessons learned from clinical trials of HIV-1 vaccines, current technologies that are being explored, and future considerations in the development of a safe and effective HIV-1 vaccine.

Effect of Platform Type on Clinical Efficacy of SARS-CoV-2 Vaccines in Prime Vaccination Settings: A Systematic Review and Meta-Regression of Randomized Controlled Trials

This systematic review investigated the association between platform type and the clinical efficacy of SARS-CoV-2 vaccines using the meta-regression of randomized controlled trials to compare the rates of the first appearance of symptomatic COVID-19 on the platforms. The trial search was conducted using PubMed, ClinicalTrials.gov, and the EU Clinical Trials Register. The main selection criteria included: non-active control, immunocompetent individuals without previous vaccination, and a low risk of bias. The platform effect was summarized with an incidence rate ratio (IRR) and a 95% confidence interval for every platform category against the reference. IRR was obtained by random-effect meta-regression with adjustment for confounding by effect modifiers. The analysis was conducted in per-protocol (PP) and modified intention-to-treat (mITT) sets. Six vaccine types with 35 trials were included. Vector vaccines were a reference category. In the PP set, rates of symptomatic COVID-19 on mRNA and protein subunit vaccines were significantly lower than on the vector: IRR = 0.30 [0.19; 0.46], p = 0.001 and 0.63 [0.46; 0.86], p = 0.012, respectively. There was no difference for inactivated and virus-like particle vaccines compared to the vector: IRR = 0.98 [0.71; 1.36], p = 0.913 and 0.70 [0.41; 1.20], p = 0.197, respectively. The rate of cases on DNA vaccines was significantly higher than that on the vector: IRR = 2.58 [1.17; 5.68], p = 0.034. Results for the mITT set were consistent. Platform type is an effect modifier of the clinical efficacy of SARS-CoV-2 vaccines.