Background: Protein-based pneumococcal vaccines (PBPVs) may offer expanded protection against Streptococcus pneumoniae and tackle the antimicrobial resistance crisis in pneumococcal infections. This study examined the safety and immunogenicity in healthy adults vaccinated with three doses of a protein-based pneumococcal vaccine containing pneumococcal surface protein A (PspA) (PRX1, P3296 and P5668) and in combination with a recombinant detoxified pneumolysin protein (PlyLD). Methods: This phase Ia randomized, double blind, placebo-controlled clinical study enrolled healthy adults aged 18–49 years. The participants were randomized into experimental (low-dose, medium-dose, high-dose) and placebo groups in a ratio of 3:1. Three doses of investigational vaccine were given to the participants with an interval of two months. Safety endpoints included the occurrence of total adverse reactions, solicited local and systemic adverse reactions, unsolicited adverse reactions, serious adverse events (SAEs), and several laboratory parameters. Immunogenicity endpoints included geometric mean titers (GMT) of anti-PspA (PRX1, P3296 and P5668) and anti-PlyLD antibodies level as determined by ELISA, seropositivity rates of PspA and PlyLD antibodies (>4-fold increase) and neutralization activity of anti-Ply antibody in serum. Results: A total of 118 participants completed the study of three doses. The candidate PBPV was safe and well-tolerated in all experimental groups. No vaccine-related SAEs were observed in this study. Most solicited adverse reactions were mild and transient. The most frequently reported solicited adverse reactions in the medium- and high-dose groups was pain at the injection site, while in the low-dose group it was elevated blood pressure. The immunogenicity data showed a sharp increase in the GMT level of anti-PspA-RX1, anti-PspA-3296, anti-PspA-5668, and anti-PlyLD antibodies in serum. The results also showed that the elicited antibodies were dosage-dependent. The high-dose group showed a higher immune response against PspA-RX1, PspA-3296, PspA-5668, and PlyLD antigens. However, repeat vaccination did not increase the level of anti-PspA antibodies but the level of anti-PlyLD antibody. High seropositivity rates were also observed for anti-PspA-RX1, anti-PspA-3296, anti-PspA-5668, and anti-PlyLD antibodies. In addition, a significant difference in the GMT levels of anti-Ply antibody between the high-, medium-, and low-dose groups post each vaccination were indicated by neutralization activity tests. Conclusions: The PBPV showed a safe and immunogenic profile in this clinical trial. Taking into consideration both safety and immunogenicity data, we propose a single dose of 50 µg (medium dose) of PBPV as the optimum approach in providing expanded protection against Streptococcus pneumoniae.

Background: Pre-existing adenovirus immunity restricts the utilization of adenovirus-vectored vaccines. The current study aims to conduct a pooled analysis of eight clinical trials to evaluate the influence of pre-existing Ad5 neutralizing antibodies on immunogenicity of Ad5-nCoV. Methods: The primary outcome indicator of this pooled analysis is the geometric mean titers (GMTs) of live SARS-CoV-2 NAbs against the wild-type strain on day 28 post-vaccination. Participants were divided into two cohorts: an adolescent cohort comprising individuals aged 6–17 years and an adult cohort with individuals aged 18 years and older. Within each cohort, individuals were further categorized into three subgroups based on their Ad5-nCoV vaccination schedules: one subgroup received a single intramuscular dose as the primary regimen (Ad5-IM-prime), another received an intramuscular dose as the heterologous prime-boost regimen (Ad5-IM-boost), and the last subgroup received an aerosolized dose as the heterologous prime-boost regimen (Ad5-IH-boost). Results: A total of 3512 participants were included in this pooled analysis. In the Ad5-IM-prime subgroup, there were 1001 adolescents and 1450 adults; in the Ad5-IM-boost subgroup, there were 65 adolescents and 396 adults; and in the Ad5-IH-boost subgroup, there were 207 adolescents and 393 adults. In the adult cohort, the GMTs of NAbs against wild-type SARS-CoV-2 on day 28 post-vaccination for the Ad5-IM-prime, Ad5-IM-boost, and Ad5-IH-boost subgroups were 35.6 (95% CI: 32.0, 39.7), 358.3 (95% CI: 267.6, 479.6), and 2414.1 (95% CI: 2006.9, 2904.0), respectively, with negative (less than 1:12) pre-existing NAb titers compared to 10.7 (95% CI: 9.1, 12.6), 116.9 (95% CI: 84.9, 161.1), and 762.7 (95% CI: 596.2, 975.8), respectively, with high (greater than 1:1000) pre-existing NAb titers. A similar trend was observed in the adolescent cohort, where pre-existing immunity was found to reduce the peak of live SARS-CoV-2 Nabs post-vaccination. Conclusions: Regardless of whether Ad5-nCoV is administered as a primary vaccination regimen or as a heterologous prime-boost strategy, a negative impact on immunogenicity can still be observed in the presence of high pre-existing immunity. However, when primary immunization is achieved with inactivated COVID-19 vaccines, aerosol inhalation can significantly enhance the immunogenicity of Ad5-nCoV compared to intramuscular injections of Ad5-nCoV as a booster.

Pertussis remains a leading cause of infant mortality globally, with rising cases in China post-COVID-19. Despite vaccination, waning immunity from acellular pertussis vaccines has driven resurgence. We evaluated a novel diphtheria, tetanus and pertussis (acellular, three components) combined vaccine, adsorbed (DTcP), China's first genetically engineered three-component pertussis vaccine, administered under two primary schedules (2/3/4 vs. 2/4/6 months) compared to licensed DTaP-IPV-Hib (Pentaxim). In this randomized, blinded, phase III clinical trial, 1380 healthy 2-month-old infants from Henan, China, received DTcP-1 (2/3/4 months) or DTcP-2 (2/4/6 months) or DTaP-IPV-Hib (2/3/4 months). The primary safety endpoints were the incidence of adverse reactions within 0∼30 days after primary vaccination. The primary immunogenicity endpoints were to evaluate the non-inferiority and superiority of seroconversion rates and geometric mean concentrations (GMCs) of anti-pertussis toxoid (PT), filamentous hemagglutinin (FHA), pertactin (PRN), diphtheria toxoid (DT), tetanus toxoid (TT), antibodies 30 days after primary vaccination. Immunogenicity was assessed via Luminex-based multiplex immunoassay. Both DTcP-1 and DTcP-2 schedules demonstrated non-inferior safety to DTaP-IPV-Hib (total adverse reactions: 14.52/16.59% vs. 16.91%, P = 0.183), with DTcP-2 (2/4/6 months) showing lower swelling (2.59% vs. 4.83%, P = 0.008) and irritability (0.07% vs. 1.02/1.40%, P < 0.001). DTcP-2 elicited higher GMCs against pertussis antigens (PT: 84.23 vs. 65.35; FHA: 132.16 vs. 102.13, both P < 0.001) and comparable DT/TT responses. DTcP exhibited favorable safety and superior pertussis immunogenicity, particularly with the 2/4/6-month schedule. Its genetically engineered three-component design offers a promising strategy to combat pertussis amid global resurgence.

Objectives: This study aimed to evaluate the immunogenicity and safety of a 13-valent pneumococcal polysaccharide conjugate vaccine (CRM197/TT) (PCV13i) in infants. Methods: A total of 1200 infants were randomly assigned to either the experimental PCV13i group or the control PCV13 group in a 1:1 ratio. Each group received a three-dose series of the vaccine at 2, 4, and 6 months of age, followed by a booster dose at 12–15 months. Blood samples were collected before and 30 days after both primary and booster vaccinations. The primary immunogenicity endpoints were the seropositive rate and the geometric mean concentration (GMC) of IgG antibodies against the 13 pneumococcal serotypes. The primary safety endpoint was the incidence of adverse reactions within 0–7 days and 0–30 days after vaccination. Results: Results showed that the experimental PCV13i was well tolerated, with a safety profile comparable to that of the control vaccine. Following primary vaccination, the GMCs of IgG responses against serotypes 1, 5, 6A, 6B, 14, and 18C in the experimental group were lower than those in the control group, while responses against serotypes 3, 4, 7F, 9V, 19A, 19F, and 23F were higher. The experimental group exhibited higher opsonophagocytic killing assay (OPA) geometric mean titers (GMTs) for serotypes 3, 7F, 19A, and 19F compared to the control group, while GMTs for serotypes 1, 5, 6A, and 18C were lower. Following booster vaccination, OPA GMTs of the experimental group remained higher than those of the control group for serotypes 3, 7F, and 19F, while GMTs for serotype 5 were lower. Both vaccines induced robust immune responses, with high seropositive rates and significant increases in antibody levels following vaccination. Conclusions: The experimental PCV13i demonstrated non-inferiority to the control PCV13 in terms of immunogenicity.

Objectives: This study systematically assessed the safety and immunogenicity of a new 13-valent pneumococcal conjugate vaccine (CRM197/TT, PCV13i) against the licensed PCV13 vaccine in a cohort of Chinese children between 12 and 23 months of age. Methods: This is a phase III, randomized, double-blind trial (NCT04841369). A total of 528 participants were randomized 1:1 to receive two doses of either PCV13i experimental or the PCV13 control vaccine at a 2-month interval, with 517 participants completing the vaccinations. Results: The overall incidence of adverse events (37.12% vs. 32.70%, p = 0.134) and adverse reactions (24.81% vs. 21.61%, p = 0.221) was comparable between the experimental and control groups. Local adverse reactions were more frequent in the experimental group (10.00% vs. 6.12%, p = 0.021), such as erythema (7.88% vs. 4.02%, p = 0.008). Systemic adverse reactions, including fever (10.77% vs. 13.77%), showed no significant differences. No vaccine-related serious adverse events occurred. Immunogenicity assessments showed that seropositivity rates for most serotypes reached ≥96% in both groups, with eight serotypes achieving 100% seropositivity in the experimental group. PCV13i induced higher IgG geometric mean concentrations (GMCs) for serotypes 3, 7F, and 19F (p < 0.05), whereas the control group showed higher GMCs for serotypes 1, 5, 6A, and 14 (p < 0.05). Opsonophagocytic activity (OPA)-related geometric mean titers (GMTs) were superior for PCV13i against serotypes 7F (39,583 vs. 17,249, p < 0.001) and 19F (1517 vs. 983, p = 0.028), but lower for serotype 5 (13 vs. 93, p < 0.001). Conclusions: PCV13i demonstrated non-inferior immunogenicity and an acceptable safety profile in 12–23-month-old children.