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The annual standard dose influenza vaccine has suboptimal immunogenicity in solid organ transplant recipients (SOTR). Influenza vaccine containing higher doses of antigens may lead to greater immunogenicity in this population. We conducted a randomized, double blind trial comparing the safety and immunogenicity of the 2016-17 high dose (HD; FluzoneHD,Sanofi) versus standard dose (SD; Fluviral,GSK) influenza vaccine in adult SOTR. Preimmunization and 4-week postimmunization sera underwent strain-specific hemagglutination inhibition assay. We enrolled 172 patients who received study vaccine and 161 (84 HD; 77 SD) were eligible for analysis. Seroconversion to at least 1 of 3 vaccine antigens was present in 78.6% vs. 55.8% in HD vs. SD vaccine respectively (p<0.001). Seroconversion to A/ H1N1, A/H3N2 and B strains were 40.5% vs. 20.5%, 57.1% vs. 32.5%, and 58.3% vs. 41.6% in HD vs. SD vaccine (p=0.006, 0.002, 0.028 respectively). Post-immunization geometric mean titers of A/H1N1, A/H3N2, and B strains were significantly higher in HD group (p=0.007, 0.002, 0.033). Independent factors associated with seroconversion to at least one vaccine strain were the use of HD vaccine (OR 3.23, 95% CI 1.56-6.67) and use of mycophenolate doses less than 2g daily (OR 2.76, 95% CI 1.12-6.76). High-dose vaccine demonstrated significantly better immunogenicity than SD vaccine in adult transplant recipients and may be the preferred influenza vaccine for this population.

The influenza vaccine is less immunogenic in older than younger adults, and the duration of protection is unclear. Determining if protection persists beyond a typical seasonal epidemic is important for climates where influenza virus activity is year-round. A systematic review protocol was developed and registered with PROSPERO [CRD42015023847]. Electronic databases were searched systematically for studies reporting haemagglutination-inhibition (HI) titres 180–360days following vaccination with inactivated trivalent seasonal influenza vaccine, in adults aged ⩾65years. Geometric mean titre (GMT) and seroprotection (HI titre ⩾1:40) at each time point was extracted. A Bayesian model was developed of titre trajectories from pre-vaccination to Day 360. In the meta-analysis, studies were aggregated using a random-effects model to compare pre-vaccination with post-vaccination HI titres at Day 21–42 (‘seroconversion’), Day 180 and Day 360. Potential sources of bias were systematically assessed, and heterogeneity explored. 2864 articles were identified in the literature search, of which nineteen met study inclusion/exclusion criteria. Sixteen studies contained analysable data from 2565 subjects. In the Bayesian model, the proportion of subjects seroprotected increased from 41–51% pre-vaccination to 75–78% at seroconversion. Seroprotection subsequently fell below 60% for all serotypes by Day 360: A/H1 42% (95% CI 38–46), A/H3 59% (54–63), B 47% (42–52). The Bayesian model of GMT trajectories revealed a similar pattern. By Day 360, titres were similar to pre-vaccination levels. In the meta-analysis, no significant difference in proportion of subjects seroprotected, 0 (−0.11, 0.11) or in log2GMT 0.30 (−0.02, 0.63) was identified by Day 360 compared with pre-vaccination. The quality of this evidence was limited to moderate on account of significant participant dropout. The review found consistent evidence that HI antibody responses following influenza vaccination do not reliably persist year-round in older adults. Alternative vaccination strategies could provide clinical benefits in regions where year-round protection is important.

We conducted a meta-analysis to evaluate the effects of probiotics and prebiotics on the immune response to influenza vaccination in adults. We conducted a literature search of Pubmed, Embase, the Cochrane Library, the Cumulative Index to Nursing and Allied Health (CINAHL), Airiti Library, and PerioPath Index to Taiwan Periodical Literature in Taiwan. Databases were searched from inception to July 2017. We used the Cochrane Review risk of bias assessment tool to assess randomized controlled trial (RCT) quality. A total of 20 RCTs comprising 1979 adults were included in our systematic review. Nine RCTs including 623 participants had sufficient data to be pooled in a meta-analysis. Participants who took probiotics or prebiotics showed significant improvements in the H1N1 strain seroprotection rate (with an odds ratio (OR) of 1.83 and a 95% confidence interval (CI) of 1.19–2.82, p = 0.006, I2 = 0%), the H3N2 strain seroprotection rate (OR = 2.85, 95% CI = 1.59–5.10, p < 0.001, I2 = 0%), and the B strain seroconversion rate (OR = 2.11, 95% CI = 1.38–3.21, p < 0.001, I2 = 0%). This meta-analysis suggested that probiotics and prebiotics are effective in elevating immunogenicity by influencing seroconversion and seroprotection rates in adults inoculated with influenza vaccines.

Influenza vaccines are important for reducing the burden of influenza, particularly for populations at risk of more severe infections. Obesity is associated with increased influenza severity and therefore individuals with obesity are often specifically recommended for annual influenza vaccination. Obesity is also associated with an altered inflammatory profile, which may influence vaccine responses. This systematic review aimed to evaluate the evidence for any association between obesity and influenza vaccine immunogenicity. Studies reporting seroprotection (SP) and/or seroconversion (SC) for obese vs non-obese recipients following licensed influenza vaccination were included. PubMed, Embase and Scopus were searched, with the final search completed on 21 Feb 2025. The protocol was registered in PROSPERO. Study selection, data extraction and critical appraisal were conducted by two reviewers in Covidence. Meta-analysis was performed in S tata 17 using a random-effects model. Of 2132 studies imported, 865 studies were screened and 140 underwent full-text review. Eleven studies reported outcomes for seroprotection and/or seroconversion for obese vs non-obese groups at 1-month following monovalent H1N1 (n = 1), trivalent (n = 6) or quadrivalent (n = 4) influenza vaccination. Studies included children (n = 5) and adults (n = 7) including pregnant women (n = 2). Study sample sizes varied from 44 to 1132 participants. Obesity was associated with a marginally higher likelihood of seroconversion or seroprotection for A/H1N1 (RR 1.04, 95 %CI 1.01–1.08; RR 1.08, 95 % CI 1.02–1.14) and marginally higher seroconversion for A/H3N2 strains (RR 1.11, 95 % CI 1.02–1.21). No significant differences were observed for Influenza B/Victoria and B/Yamagata strains. Obesity does not impair influenza vaccine immunity at one-month post-vaccination, and may enhance antibody responses, potentially due to a proinflammatory immune profile. •Obesity is not linked to impaired antibody responses to influenza vaccination.•H1N1 seroprotection and seroconversion were marginally higher in obese groups•These findings support current influenza vaccine policy and recommendations.

Bacillus Calmette-Guérin vaccine (BCG), one of the most widely used vaccines, does not only provide protection against tuberculosis and other mycobacterial infections, but also has non-specific (heterologous) immunomodulatory effects. In participants in a randomised trial, we investigated the effect of neonatal BCG immunisation on antibody responses to routine infant vaccines given in the first year of life. Antibodies against antigens in the diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b (Hib), and the 13-valent pneumococcal conjugate vaccines were measured in 91 (45 BCG-vaccinated, 46 BCG-naïve) infants one month after, and in 310 (169 BCG-vaccinated, 141 BCG-naïve) infants seven months after immunisation at 6 weeks, 4 and 6 months of age. In addition, antibodies against meningococcus C, Hib, measles, mumps, and rubella were measured in 147 (78 BCG-vaccinated, 69 BCG-naïve) infants one month after immunisation at 12 months of age. The seroprotection rates for each vaccine and the geometric mean concentrations (GMC) of antibodies were compared in BCG-vaccinated and BCG-naïve infants. At 7 months of age, seroprotection rates were high in both BCG-vaccinated and BCG-naïve infants. At 13 months of age, seroprotection rates were lower than at 7 months of age, particularly for pertussis and a number of pneumococcal antigens, with generally higher rates for the latter in BCG-vaccinated infants. Although not statistically significant, antibody responses in BCG-vaccinated infants were consistently higher against diphtheria, tetanus, and pneumococcal antigens at both 7 and 13 months of age, and against measles and mumps at 13 months of age, but were lower against Hib one month after immunisation at both 7 and 13 months of age. The immunomodulatory effect of BCG on antibody responses to heterologous vaccines adds to the evidence that BCG immunisation at birth has broad heterologous effects on the infant immune system.

Due to the nature of their work, healthcare personnel are at an increased risk for hepatitis B infection, and some may not respond fully to the vaccine. Many health systems evaluate hepatitis B vaccine response of new employees with history of vaccines series completion at time of hire. Individuals found to have hepatitis B antibodies (anti-HBs) that are negative, or borderline (non-immune) may receive a challenge dose. Hepatitis B vaccine with CpG adjuvant (hepB-CpG) has shown higher response rates compared to hepatitis B vaccine with aluminum adjuvants (hepB-Alum) in many populations. The aim of this study is to determine if individuals with negative or borderline (non-immune) levels of anti-HBs at time of hire, despite previous vaccination, are more likely to respond to hepB-CpG or hepB-Alum challenge dose. For an individual to be considered eligible, the following criteria must be met: (1) history of hepB-Alum series completion, (2) anti-HBs assay that are negative or borderline (non-immune) at hire, (3) received challenge dose (hepB-CpG or hepB-Alum), (4) had post-challenge dose antiHBs measured. Of immunized individuals who were anti-HBs negative or borderline (non-immune) at hire, 1020/1049 (97.2%) responded to the hepB-CpG challenge dose compared to 877/1006 (87.2%) who responded to the hepB-Alum challenge dose (p < 0.001). Among those who received hepB-CpG challenge dose, those whose primary series was the pediatric preparation were more likely to respond to the challenge dose compared to those who receive the adult vaccine preparation as their primary series. (pediatric 959/983 (97.6%) vs adult 62/67 (93.5%) p = 0.033), but no hepB-Alum response rate difference was found for pediatric vs adult primary series. HepB-CpG challenge dose was associated with a higher response rate compared to hepB-Alum challenge dose and should be considered the preferred vaccine preparation for this situation. •Retrospective study of healthcare personnel who had hepB vaccine series.•Higher vaccine challenge dose response rates to hepB-CpG than hepB-Alum.•HepB-CpG challenge dose should be used preferentially

People living with HIV (PLHIV) exhibit reduced seroprotection and faster antibody waning after hepatitis B virus (HBV) vaccination. Data on long-term persistence and immunological memory following enhanced vaccination schedules are limited. In this interventional study, PLHIV who previously responded to a modified primary HBV vaccination schedule (four 40-μg doses) were reassessed after a median follow-up of 14.5 years. Anti-HBs titers were measured before and 1–6 months after administration of a 40 μg HBV booster dose. Among 75 participants, 81,3% maintained seroprotective anti-HBs levels, with 59% classified as strong responders (≥ 100 mIU/mL). Although titers declined over time, 96% achieved seroprotection after the booster dose, demonstrating a robust anamnestic response. Higher post-primary vaccination anti-HBs titers independently predicted both long-term seroprotection and post-booster responses. The modified HBV vaccination schedule induced durable seroprotection and confirmed persistent immunological memory in PLHIV more than a decade after primary immunization.

Heplisav-B, a CpG-adjuvanted recombinant hepatitis B virus (HBV) vaccine, has a higher seroprotection rate and immunogenicity than the conventional HBV vaccine. This study aimed to identify the predictors of HBV seroprotection post-transplantation in thoracic organ transplant recipients who received Heplisav-B. We conducted a retrospective study of adult thoracic organ (heart and lung) transplant recipients at Mayo Clinic sites in Minnesota, Arizona, and Florida between January 2020 and August 2023. Patients who completed Heplisav-B series were classified into three strategies: strategy A (completed 2 doses of Heplisav-B pre-transplantation with achieved seroprotection pre-transplantation), strategy B (received first dose of Heplisav-B pre-transplantation and second dose of Heplisav-B post-transplantation), and strategy C (completed 2 doses of Heplisav-B post-transplantation). HBV seroprotection was defined as HBsAb ≥10 IU/L. A total of 154 thoracic organ transplant recipients completed Heplisav-B vaccine series. Post-transplant seroprotection was highest in strategy A, followed by strategy B and strategy C (54/76 [71 %] vs. 18/39 [46 %] vs. 14/39 [36 %]; p < 0.001). Multivariate logistic regression analysis identified two independent factors predicting lack of HBV seroprotection post-transplantation; both were related to Heplisav-B schedule: strategy B (adjusted odds ratio [aOR], 2.482; 95 % confidence interval [CI] 1.085 5.679; p = 0.031), and strategy C (aOR 4.963; 95 % CI 2.106 11.697; p < 0.001). The vaccine schedule significantly predicts HBV seroprotection in adult thoracic organ transplant recipients. Our data supports the recommendation that pre-transplantation Heplisav-B to achieve HBsAb ≥10 IU/L is the optimal vaccination schedule to maintain an HBsAb level of ≥10 IU/L post-transplantation. Further studies are needed to determine whether this observation can be replicated in non-thoracic organ transplant recipients or pediatric populations.

Prevention of hepatitis B virus (HBV) infection by vaccination can potentially eliminate HBV-related diseases. PreHevbrio™/PreHevbri® is a 3-antigen (S, preS1, preS2) HBV vaccine (3A-HBV) recently licensed for adults in the US, EU and Canada. This study evaluated antibody persistence in a subset of fully vaccinated and seroprotected (anti-HBs ≥ 10 mIU/mL) Finnish participants from the phase 3 trial (PROTECT) of 3A-HBV versus single-antigen HBV vaccine (1A-HBV). 465/528 eligible subjects were enrolled (3A-HBV: 244; 1A-HBV: 221). Baseline characteristics were balanced. After 2.5 years, more 3A-HBV subjects remained seroprotected (88.1 % [95 %CI: 84.1,92.2]) versus 1A-HBV (72.4 % [95 %CI: 66.6,78.3)], p < 0.0001) and had higher mean anti-HBs [1382.9 mIU/mL (95 %CI: 1013.8,1751.9) versus 252.6 mIU/mL (95 %CI: 127.5,377.6), p < 0.0001]. In multiple variable logistic regression analysis including age, vaccine, initial vaccine response, sex and BMI, only higher post dose 3 (Day 196) antibody titers significantly reduced the odds of losing seroprotection.

The burden of Japanese encephalitis (JE) is substantial and is arguably one of the most serious viral encephalitic diseases with high case fatality and no specific treatment. JE vaccines are the only available mean to prevent the disease; however, the long-term persistence of antibodies, boostability, and interchangeability between different vaccine classes are not well understood. To summarise the evidence, PubMed, Embase, and Cochrane CENTRAL were systematically searched from their inception to March 2021. Dose-response meta-analysis was utilised to synthesise the proportion of individuals who were seropositive over time after a primary vaccination course and a booster dose. Proportion meta-analysis was conducted to estimate the proportion of individuals who were seropositive as well as those who reported adverse events following a booster dose with a different vaccine class. Of 1053 publications retrieved, 27 studies with 4,558 participants were included. Of these, 11 studies assessed persistence of antibodies, 14 studies boostability, and 8 vaccine class interchangeability. The pooled seropositivity, 1-year after primary vaccination was 83.4% (95 %CI 78.2–89.5%) and remained stable for up to 5 years (82.7%; 95 %CI 76.1–89.4%). Rapid anamnestic response was observed 10 days post-booster dose, the proportion of individuals who were seropositive reached 96.9% (95 %CI 95.9–97.8%) and remained > 95% for up to 6 years. Inactivated mouse brain-derived vaccines followed by a booster dose of a different vaccine class was effective (i.e. seropositive 99%) and well tolerated. A booster dose after the primary vaccination is effective and further booster doses may be needed after 7 years. Inactivated mouse brain-derived vaccine followed by a booster with a newer vaccine class is effective and safe; although, there is a paucity of data related to newer classes of vaccines interchangeability.