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.

A half-dose influenza vaccine (7.5 μg hemagglutinin per strain) has been used for children under 3 years of age for a long time. However, several studies indicate that a full-dose influenza vaccine (15 μg hemagglutinin per strain) may bring more benefit to this population without increasing the risk of adverse reactions. We conducted a clinical study in children aged 6-35 months in China. Participants were randomized to receive two doses of full-dose quadrivalent influenza vaccine (F-QIV), half-dose quadrivalent vaccine (H-QIV), and two half-dose trivalent vaccines (H-TIV) in a 2:2:1:1 ratio. The safety and tolerability profile of the vaccine was evaluated for 6 months postvaccination. Hemagglutination inhibition (HI) antibody titers were measured for immunogenicity assessment. The primary objective was to assess whether the results of all vaccines met the criteria. A total of 1,980 participants were enrolled in the study. Both H-QIV and F-QIV were well tolerated after vaccination. Although the geometric mean increase (GMI), seroconversion rate (SCR), and seroprotection rate (SPR) for both H-QIV and F-QIV were achieved by the criteria, superior immunogenicity in terms of geometric mean titer (GMT) ratio was observed in F-QIV to H-QIV for A/H3N2 (GMT ratio (95% CI) of 1.37 (1.11 ~ 1.68)) and B/Yamagata (1.21 (1.05 ~ 1.39)). Antibody responses to the QIV were non-inferior to the response to the TIV for the matched strains. In conclusion, F-QIV and H-QIV were both safe and immunogenic for children. F-QIV induced a stronger immune response to influenza viruses and may provide more protection and benefit by promoting the use of F-QIV in children aged 6-35 months.

Background: In recent years, breakthrough varicella cases among individuals who have received a single dose of varicella vaccine (VarV) have increased notably, suggesting that the long-term protection following a one-dose VarV regimen requires further investigation. This study aims to evaluate the immune persistence following a single dose of Sinovac VarV at 5 and 8 years post-vaccination. Methods: In this Phase 4, open-label, observational follow-up study, participants aged 1 to 12 years (referring to the age of vaccination) who had received a single dose of either Sinovac VarV or placebo in the previous phase 3 trial were enrolled in a 1:1 ratio. Blood samples were collected 5 years and 8 years post-vaccination to measure antibody levels against varicella using the fluorescent antibody to membrane antigen (FAMA) method. A total of 487 and 422 participants were included in the 5-year and 8-year immune persistence analyses, respectively. The endpoints comprised the seropositive rates (≥1:4 and ≥1:8) and the geometric mean titers (GMTs) of varicella antibodies at both 5 and 8 years following vaccination. Results: Varicella antibody levels declined from 30 days post vaccination but remained stable from 5 to 8 years. Five years after vaccination, the seropositive rates (≥1:4) of varicella antibody were 100% in the VarV group and 80.83% in the placebo group; for ≥1:8, the rates were 89.07% and 64.17%, respectively. The corresponding GMTs were 1:13.67 and 1:7.71, respectively. Eight years after vaccination, the seropositive rates (≥1:4) were 99.54% in the VarV group and 90.69% in the placebo group; for ≥1:8, they were 88.53% and 74.51%, with GMTs of 1:13.52 and 1:9.91, respectively. Eight years post-vaccination, the seropositive rates and antibody levels in the VarV group remained nearly the same as by 5 years. Conclusions: Sinovac VarV can confer good immune persistence for up to 8 years following a single dose of vaccination in children aged 1 to 12 years. However, given the declining trend in antibody levels over time, revaccination may be needed to maintain protective immunity.

In the postpandemic era, populations may experience an "immunity debt" due to reduced social interactions. Studying respiratory co-infections in populations is of great significance for precise treatment and the prevention and control of infectious disease outbreaks. A prospective surveillance network was established across 24 sentinel hospitals. Respiratory specimens were collected. Nucleic acids were extracted using magnetic bead-based methods and tested by real-time PCR for 10 viruses and 5 bacterial targets. Data were analyzed to determine positivity rates, co-infections, and age-specific patterns using Join-Point Regression. The overall pathogen positivity rate was 64.3% (9954/15,481). Co-infection with ≥2 pathogens was detected in 26.7% of patients. Influenza virus (IFV) was the predominant virus (20.9% overall), peaking in January 2025 (49.4%). Human metapneumovirus was the second most common virus (8.0%). Haemophilus influenzae (21.1%) and Streptococcus pneumoniae (17.7%) were the most frequently detected bacteria. Positivity rates exhibited significant age-related variation. Join-Point analysis revealed that the IFV positivity rate increased until age 50. Considerable geographic variation was observed, with the total positivity rate ranging from 53.2% to 82.2% across different cities. This comprehensive surveillance revealed a high burden of respiratory pathogens and complex co-infection patterns in the postpandemic era.

Background: We performed a phase I experiment in a healthy teenage population in Sui County, Henan Province, China. The trial was randomized, double-blind, and placebo-controlled. Methods: Ninety-six adolescents were randomly assigned in three groups (high-dose, medium-dose, and low-dose) to receive a dose of the vaccine or the placebo. The patients were monitored for adverse events (AEs) for up to 30 days after each dose of the vaccine and for up to 6 months after all doses of serious AEs (SAEs). All observed AEs and SAEs were reported. Microneutralization assays were used to measure geometric mean titers (GMTs) and seroconversion rates for neutralizing antibodies. IgA and IgG antibodies specific to the rotavirus were detected. Results: The rates of total AEs in these groups were 8.33%, 37.50%, 12.50%, and 4.17%, respectively. The neutralizing antibody test revealed that the teenage groups with low, medium, and high doses of the vaccine had geometric mean titers of 424.32, 504.63, and 925.45, respectively, at 28 days following complete vaccination. The GMT of serum IgG at final immunization was 6501.86, 6501.82, and 10,173.3, in the low-dose, medium-dose, and high-dose groups, respectively. The GMT of serum IgA at final immunization was 2733.64, 2233.29, and 3596.66 in the low-dose, medium-dose group, and high-dose groups, respectively. Conclusions: The majority of adverse events (AEs) were deemed Grade 1 or 2, suggesting that the vaccine’s safety profile is suitable for healthy adolescents. For the primary immunogenicity endpoints, a preliminary examination of the GMTs and the positive transfer rate of neutralizing antibodies in the different experimental groups revealed that, in adolescents aged 6–17, the high-dose group displayed significantly higher levels of neutralizing antibodies compared to the medium- and low-dose groups. Adolescents had few side effects from the new inactivated rotavirus vaccination, and it elicited an immune response.