Immunogenicity and safety of BNT162b2 mRNA vaccine in Chinese adults: A phase 2 randomised clinical trial

Immunogenicity and safety of a COVID-19 DNA vaccine in healthy adults and elderly: A randomized, observer-blind, placebo-controlled phase 2 trial

INO-4800 represents a DNA-based vaccine encoding the spike protein of SARS-CoV-2. This phase 2 trial evaluated the immunogenicity and safety of INO-4800 as a primary vaccination series in adults. We conducted a randomized, observer-blind, placebo-controlled phase 2 trial of intradermal injection of INO-4800 in both healthy adults and elderly individuals. Eligible participants from each age group were enrolled and randomly assigned in a 3:3:2 ratio to receive two doses of INO-4800 (1.0 mg or 2.0 mg) or placebo, followed by electroporation on day 0 and day 28. The primary immunogenicity endpoints focused on determining the geometric mean titers (GMTs) of spike-binding antibodies and live SARS-CoV-2 neutralizing antibody at day 30 after the second dose. The primary endpoint for safety was the occurrence of adverse events within 30 days after vaccination. A total of 781 volunteers were recruited and screened for eligibility, with 320 eligible young adults (≥18 to <60 years old) and 320 elderly (≥60 to ≤85 years old) were randomly assigned to receive the low-dose (1.0 mg, n = 120) or high-dose (2.0 mg, n = 120) INO-4800, or placebo (n = 80). Notably, both dose groups exhibited significant increases in spike-binding antibodies at day 30 after the second dose, with GMTs of 1609.3 (95% CI: 1385.5-1869.3) for the low-dose group and 3016.7 (95% CI: 2577.4-3530.8) for the high-dose group. Additionally, both dose groups induced neutralizing antibodies against live SARS-CoV-2, with GMTs of 4.7 (95% CI: 4.2-5.3) and 6.6 (95% CI: 5.9-7.4) at day 30 after the second dose. The incidence of adverse events within 30 days after vaccination was slightly higher in the high-dose group (115 [47.9%]) than that in the low-dose group (105 [43.8%]) (p = .0060). All adverse reactions were grade 1 or 2, primarily occurring within 14 days after vaccination. No vaccine-related serious adverse events were reported. The COVID-19 DNA vaccine INO-4800 at two doses (1.0 mg or 2.0 mg) showed an acceptable safety profile and modest immunogenicity, with the high-dose slightly more immunogenic than the low-dose.Clinical Trials Registration: www.chictr.org.cn, identifier is ChiCTR2000040146.

Comparative duration of neutralizing responses and protections of COVID-19 vaccination and correlates of protection

The decline in neutralizing antibody (nAb) titers and vaccine efficacy /effectiveness (VE) for SARS-CoV-2 vaccines has been observed over time and when confronted with emerging variants, two factors that are hard to distinguish. Despite substantial drop in nAb titers against Omicron, VE remains high for severe cases and fatalities, raising questions about the utility of detected nAbs as a correlate of protection for COVID-19 vaccines for varying disease severity. Here, we conducted a systematic comparison of waning dynamics of nAb and VE over time and against variants with varying levels of disease severity. Using Bayesian linear regression models, we found that antigenically-shifted variants, like Omicron, could potentially lead to greater reductions in nAb titers and primary VE against mild infections than associated immunity waning observed over a 180-day period. By comparing model predicted nAb titers and VE on the same time scales, we found that VE against severe and fatal outcomes remained above 75% even when nAb titers reached the detectable limit of assays, despite strong correlations with nAb titers (spearman correlations ≥0.7) across variants over time. This finding suggested detectable nAb titers are not always sensitive enough to fully predict protection against severe disease and death from SARS-CoV-2.

Safety and reactogenicity of the BNT162b2 COVID-19 vaccine: Development, post-marketing surveillance, and real-world data

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to urgent actions by innovators, vaccine developers, regulators, and other stakeholders to ensure public access to protective vaccines while maintaining regulatory agency standards. Although development timelines for vaccines against SARS-CoV-2 were much quicker than standard vaccine development timelines, regulatory requirements for efficacy and safety evaluations, including the volume and quality of data collected, were upheld. Rolling review processes supported by sponsors and regulatory authorities enabled rapid assessment of clinical data as well as emergency use authorization. Post-authorization and pharmacovigilance activities enabled the quantity and breadth of post-marketing safety information to quickly exceed that generated from clinical trials. This paper reviews safety and reactogenicity data for the BNT162 vaccine candidates, including BNT162b2 (Comirnaty, Pfizer/BioNTech COVID-19 vaccine) and bivalent variant-adapted BNT162b2 vaccines, from preclinical studies, clinical trials, post-marketing surveillance, and real-world studies, including an unprecedentedly large body of independent evidence.

The Assessment of Anti-SARS-CoV-2 Antibodies in Different Vaccine Platforms: A Systematic Review and Meta-Analysis of COVID-19 Vaccine Clinical Trial Studies

BACKGROUND AND OBJECTIVE

The COVID-19 pandemic spread rapidly throughout the world and caused millions of deaths globally. Several vaccines have been developed to control the COVID-19 pandemic and reduce the burden it placed on public health. This study aimed to assess the efficacy of different vaccine platforms in inducing potent antibody responses. Moreover, the seroconversion rate and common side effects of vaccine platforms were evaluated.

METHODS

This meta-analysis included clinical trials of COVID-19 vaccines that met the eligibility criteria. Electronic databases (including PubMed, Scopus, and Web of Science) and Google Scholar search engine were searched for eligible studies. Regarding the methodological heterogeneity between the included studies, we selected a random-effects model. The geometric mean ratio (GMR) was chosen as the effect size for this meta-analysis.

RESULTS

Of the 1838 records identified through screening and after removing duplicate records, the full texts of 1076 records were assessed for eligibility. After the full-text assessment, 56 records were eligible and included in the study. Overall, vaccinated participants had a 150.8-fold increased rate of anti-spike IgG titres compared with the placebo group (GMR = 150.8; 95% CI, 95.9-237.1; I2 = 100%). Moreover, vaccinated participants had a 37.3-fold increased rate of neutralising antibody titres compared with the placebo group (GMR = 37.3; 95% CI, 28.5-48.7; I2 = 99%). The mRNA platform showed a higher rate of anti-spike IgG (GMR = 1263.5; 95% CI, 431.1-3702.8; I2 = 99%), while neutralising antibody titres were higher in the subunit platform (GMR = 53.4; 95% CI, 32.8-87.1; I2 = 99%) than in other platforms. Different vaccine platforms showed different rates of both anti-spike IgG and neutralising antibody titres with interesting results. The seroconversion rate of anti-spike IgG and neutralising antibody titres was more than 98% in the vaccinated participants.

CONCLUSION

Inactivated and subunit vaccines produced a high percentage of neutralising antibodies and had a low common adverse reaction rate compared to other platforms. In this regard, subunit and inactivated vaccines can still be used as the main vaccine platforms for effectively controlling infections with high transmission rates.

Safety and immunogenicity of primary vaccination with a SARS-CoV-2 mRNA vaccine (SYS6006) in Chinese participants aged 18 years or more: Two randomized, observer-blinded, placebo-controlled and dose-escalation phase 1 clinical trials

Vaccination plays a key role in preventing morbidity and mortality caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to evaluate the safety and immunogenicity of a SARS-CoV-2 messenger ribonucleic acid (mRNA) vaccine SYS6006. In the two randomized, observer-blinded, placebo-controlled phase 1 trials, 40 adult participants aged 18-59 years and 40 elderly participants aged 60 years or more were randomized to receive two doses of SYS6006 or placebo (saline). Adverse events (AEs) were collected through 30 days post the second vaccination. Immunogenicity was assessed by live-virus neutralizing antibody (Nab), spike protein (S1) binding antibody (S1-IgG), and cellular immunity. The result showed that 7/15, 9/15 and 4/10 adult participants, and 9/15, 8/15 and 4/10 elderly participants reported at least one AE in the 20-µg, 30-µg and placebo groups, respectively. Most AEs were grade 1. Injection-site pain was the most common AE. Two adults and one elder reported fever. No vaccination-related serious AE was reported. SYS6006 elicited wild-type Nab response with a peak geometric mean titer of 232.1 and 130.6 (adults), and 48.7 and 66.7 (elders), in the 20-µg and 30-µg groups, respectively. SYS6006 induced moderate-to-robust Nab response against Delta, and slight Nab response against Omicron BA.2 and BA.5. Robust IgG response against wild type and BA.2 was observed. Cellular immune response was induced. In conclusion, two-dose primary vaccination with SYS6006 demonstrated good safety and immunogenicity during a follow-up period of 51 days in immunologically naive population aged 18 years or more. (Trial registry: Chictr.org.cn ChiCTR2200059103 and ChiCTR2200059104).

Approach to COVID-19 in older adults and indications for improving the outcomes

Background: COVID-19 continues to present challenges in the care of older adults with frailty and/or comorbidities and very old patients, who can be hospitalized with severe COVID-19 despite full vaccination. Frailty is a heterogeneous syndrome characterized by an increased aging-related vulnerability due to a reduced physiological reserve and function of systemic organs, and is associated with an impairment of activities of daily living. Frail older adults remain at elevated risk of mortality from COVID-19 compared to older adults without frailty, and some pre-existing risk factors such as malnutrition, prolonged bed rest, and the association with comorbidities can aggravate the SARS-CoV-2 infection. Furthermore, the severity of COVID-19 can impact on long-term functioning of older patients surviving from the infection. Persistent symptoms are another emerging problem of the post-vaccination phase of pandemic, as most patients suffer from chronic symptoms which can become debilitating and affect the daily routine. Aim of this review: In this complex relationship, the evaluation of COVID-19 in vulnerable categories is still a matter of high interest and personalized care plans based on a comprehensive geriatric assessment, tailored interventions; specific therapeutic algorithms among older adults are thus recommended in order to improve the outcomes.

mRNA-Based Vaccine for COVID-19: They Are New but Not Unknown!

mRNA vaccines take advantage of the mechanism that our cells use to produce proteins. Our cells produce proteins based on the knowledge contained in our DNA; each gene encodes a unique protein. The genetic information is essential, but cells cannot use it until mRNA molecules convert it into instructions for producing specific proteins. mRNA vaccinations provide ready-to-use mRNA instructions for constructing a specific protein. BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) both are newly approved mRNA-based COVID-19 vaccines that have shown excellent protection and efficacy. In total, there are five more mRNA-based vaccine candidates for COVID-19 under different phases of clinical development. This review is specifically focused on mRNA-based vaccines for COVID-19 covering its development, mechanism, and clinical aspects.

COVID-19 mRNA Vaccine Effectiveness against Elderly Frail People

The frail, elderly population is often characterized by poor immunogenicity post COVID-19 mRNA vaccination. "Inflame-ageing" and "immune-senescence" are pathogenetic mechanisms that might explain this phenomenon. Complex interplay with cytokines and microbiota is also implicated in this inflammatory cascade. The abovementioned population, although very important from immunologic perspective, has barely been included in the mRNA vaccination clinical trials.