Antibody Seroconversion Rates Research Articles

An Omicron-specific, self-amplifying mRNA booster vaccine for COVID-19: a phase 2/3 randomized trial

Here we conducted a multicenter open-label, randomized phase 2 and 3 study to assess the safety and immunogenicity of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron-specific (BA.1/B.1.1.529), monovalent, thermostable, self-amplifying mRNA vaccine, GEMCOVAC-OM, when administered intradermally as a booster in healthy adults who had received two doses of BBV152 or ChAdOx1 nCoV-19. GEMCOVAC-OM was well tolerated with no related serious adverse events in both phase 2 and phase 3. In phase 2, the safety and immunogenicity of GEMCOVAC-OM was compared with our prototype mRNA vaccine GEMCOVAC-19 (D614G variant-specific) in 140 participants. At day 29 after vaccination, there was a significant rise in anti-spike (BA.1) IgG antibodies with GEMCOVAC-OM (P < 0.0001) and GEMCOVAC-19 (P < 0.0001). However, the IgG titers (primary endpoint) and seroconversion were higher with GEMCOVAC-OM (P < 0.0001). In phase 3, GEMCOVAC-OM was compared with ChAdOx1 nCoV-19 in 3,140 participants (safety cohort), which included an immunogenicity cohort of 420 participants. At day 29, neutralizing antibody titers against the BA.1 variant of SARS-CoV-2 were significantly higher than baseline in the GEMCOVAC-OM arm (P < 0.0001), but not in the ChAdOx1 nCoV-19 arm (P = 0.1490). GEMCOVAC-OM was noninferior (primary endpoint) and superior to ChAdOx1 nCoV-19 in terms of neutralizing antibody titers and seroconversion rate (lower bound 95% confidence interval of least square geometric mean ratio >1 and difference in seroconversion >0% for superiority). At day 29, anti-spike IgG antibodies and seroconversion (secondary endpoints) were significantly higher with GEMCOVAC-OM (P < 0.0001). These results demonstrate that GEMCOVAC-OM is safe and boosts immune responses against the B.1.1.529 variant. Clinical Trial Registry India identifier: CTRI/2022/10/046475.

Immunogenicity and safety of boosting with a recombinant two-component SARS-CoV-2 vaccine: two randomized, parallel-controlled, phase 2 studies

ABSTRACT Background Recombinant protein vaccines are vital for broad protection against SARS-CoV-2 variants. This study assessed ReCOV as a booster in two Phase 2 trials. Research design and methods Study-1 involved subjects were randomized (1:1:1) to receive 20 μg ReCOV, 40 μg ReCOV, or an inactivated vaccine (COVILO®) in the United Arab Emirates. Study-2 participating individuals were randomized (1:1:1) to receive 20 μg ReCOV (pilot batch, ReCOV HA), 20 μg ReCOV (commercial batch, ReCOV TC), or 30 μg BNT162b2 (COMIRNATY®) in the Philippines. The primary immunogenicity objectives was to compare the geometric mean titer (GMT) and seroconversion rate (SCR) of neutralizing antibodies induced by one ReCOV booster dose with those of inactivated vaccine and BNT162b2, respectively, at 14 days post-booster. Results Heterologous ReCOV booster doses were safe and induced comparable immune responses to inactivated vaccines and BNT162b2 against Omicron variants and the prototype. They showed significant advantages in cross-neutralization against multiple SARS-CoV-2 variants, surpassing inactivated vaccines and BNT162b2, with good immune persistence. Conclusions Heterologous ReCOV boosting was safe and effective, showing promise in combating COVID-19. The study highlights ReCOV’s potential for enhanced protection, supported by strong cross-neutralization and immune persistence. Clinical Trial Registration Study-1, www.clinicaltrials.gov, identifier is NCT05323435; Study-2, www.clinicaltrials.gov, identifier is NCT05084989.

Mpox Neutralizing Antibody Response to LC16m8 Vaccine in Healthy Adults

BackgroundVaccination against mpox (formerly known as monkeypox), an infectious disease caused by the monkeypox virus (MPXV), is needed to prevent outbreaks and consequent public health concerns. The LC16m8 vaccine, a dried cell-cultured proliferative live attenuated vaccinia virus–based vaccine, was approved in Japan against smallpox and mpox. However, its immunogenicity and efficacy against MPXV have not been fully assessed. We assessed the safety and immunogenicity of LC16m8 against MPXV in healthy adults.MethodsWe conducted a single-arm study that included 50 participants who were followed up for 168 days postvaccination. The primary end point was the neutralizing antibody seroconversion rate against MPXVs, including the Zr599 and Liberia strains, on day 28. The secondary end points included the vaccine “take” (major cutaneous reaction) rate, neutralizing titer kinetics against MPXV and vaccinia virus (LC16m8) strains, and safety outcomes.ResultsSeroconversion rates on day 28 were 72% (36 of 50), 70% (35 of 50), and 88% (44 of 50) against the Zr599 strain, the Liberia strain, and LC16m8, respectively. On day 168, seroconversion rates decreased to 30% (15 of 50) against the Zr599 and Liberia strains and to 76% (38 of 50) against LC16m8. The vaccine “take” (broad definition) rate on day 14 was 94% (46 of 49). Adverse events (AEs), including common solicited cutaneous reactions, occurred in 98% (45 of 48) of participants; grade 3 severity AEs occurred in 16% (8 of 50). No deaths, serious AEs, or mpox onset incidences were observed up to day 168.ConclusionsThe LC16m8 vaccine generated neutralizing antibody responses against MPXV in healthy adults. No serious safety concerns occurred with LC16m8 use. (Funded by the Ministry of Health, Labour and Welfare of Japan; Japan Registry of Clinical Trials number, jRCTs031220171.)

Safety of the novel oral poliovirus vaccine type 2 (nOPV2) in infants and young children aged 1 to

Novel oral poliovirus vaccine type 2 (nOPV2) has been engineered to improve the genetic stability of Sabin oral poliovirus vaccine (OPV) and reduce the emergence of circulating vaccine-derived polioviruses. This trial aimed to provide key safety and immunogenicity data required for nOPV2 licensure and WHO prequalification. This phase 3 trial recruited infants aged 18 to <52 weeks and young children aged 1 to <5 years in The Gambia. Infants randomly assigned to receive one or two doses of one of three lots of nOPV2 or one lot of bivalent OPV (bOPV). Young children were randomised to receive two doses of nOPV2 lot 1 or bOPV. The primary immunogenicity objective was to assess lot-to-lot equivalence of the three nOPV2 lots based on one-dose type 2 poliovirus neutralising antibody seroconversion rates in infants. Equivalence was declared if the 95% CI for the three pairwise rate differences was within the -10% to 10% equivalence margin. Tolerability and safety were assessed based on the rates of solicited adverse events to 7 days, unsolicited adverse events to 28 days, and serious adverse events to 3 months post-dose. Stool poliovirus excretion was examined. The trial was registered as PACTR202010705577776 and is completed. Between February and October, 2021, 2345 infants and 600 young children were vaccinated. 2272 (96·9%) were eligible for inclusion in the post-dose one per-protocol population. Seroconversion rates ranged from 48·9% to 49·2% across the three lots. The minimum lower bound of the 95% CIs for the pairwise differences in seroconversion rates between lots was -5·8%. The maximum upper bound was 5·4%. Equivalence was therefore shown. Of those seronegative at baseline, 143 (85·6%) of 167 (95% CI 79·4-90·6) infants and 54 (83·1%) of 65 (71·7-91·2) young children seroconverted over the two-dose nOPV2 schedule. The post-two-dose seroprotection rates, including participants who were both seronegative and seropositive at baseline, were 604 (92·9%) of 650 (95% CI 90·7-94·8) in infants and 276 (95·5%) of 289 (92·4-97·6) in young children. No safety concerns were identified. 7 days post-dose one, 78 (41·7%) of 187 (95% CI 34·6-49·1) infants were excreting the type 2 poliovirus. nOPV2 was immunogenic and safe in infants and young children in The Gambia. The data support the licensure and WHO prequalification of nOPV2. Bill & Melinda Gates Foundation.

The Effects of Dairy Consumption on Vaccine Immune Response and Immunoglobulins: A Systematic Literature Review

Public health interest in vaccinations and immune protection has increased with the COVID-19 pandemic. Dairy products are an important source of protein and other nutrients, and there are unresolved research questions regarding the potential health impact of dairy products on the enhancement of immune response. A systematic literature review was conducted to synthesize the published literature reporting the effects of dairy interventions on: 1) the vaccine-specific immune response and 2) immunoglobulins in the absence of vaccination. To assess study validity and quality, we used the Academy of Nutrition and Dietetics Quality Criteria Checklist. Sixty-one studies (59 clinical trials, 1 cohort, 1 cross-sectional survey) were included, spanning 1983-2017. Ten trials evaluated the effect of dairy intervention on vaccine-specific IgG, IgA, IgM, vaccine-specific antibody titers, seroprotection rates, or seroconversion rates. Of these, 7 reported significant increases with dairy interventions for post-vaccine tetanus antibodies, mean change in tetanus antibody level, total antibody titers to flagellin from Salmonella Adelaide, mean antibody titers to influenza B, influenza-specific IgA and IgG levels, and seroconversion or seroprotection rates for influenza A and B. Fifty-six studies evaluated dairy’s effects on immunoglobulins without vaccinations. The results were heterogenous, with some studies reporting significant enhancement of immunoglobulins (IgA, IgE, or IgG), while others observed no differences between groups. Clinical relevance of the immunoglobulin changes was not investigated in these studies. Dairy products and their components could enhance the efficacy of vaccines. This review highlights the evidence gaps and provides a potential roadmap for additional research.

Attenuation of hepatitis A antibody after immunization with hepatitis A vaccine (Aimmugen) in people living with HIV.

Hepatitis A (HA) is a vaccine-preventable disease. In regions with good sanitation, men who have sex with men (MSM) are the key affected populations. During the 2018-2019 HA outbreak among MSM in Japan, we actively vaccinated MSM living with HIV (MSM-LWHIV) with Aimmugen. As previously reported, their antibody seroconversion rate due to vaccination was lower than that of healthy individuals. However, the durability of Aimmugen in people living with HIV has not yet been reported. We evaluated attenuation after the one-series vaccination (comprising three inoculations) and the factors associated with attenuation. We retrospectively examined anti-HA immunoglobulin G (anti-HA-IgG) titers and other clinical data from our hospital's medical records. Patients with no history of vaccination or HA infection (i.e., negative HA-IgG titers) who received one series of Aimmugen, achieved seropositivity, and anti-HA-IgG antibodies were tested ≥2years after three doses were included. Fisher's exact test and the Mann-Whitney U-test were performed. p<0.05 was considered statistically significant. Fifty-one MSM-LWHIV were included. All were seropositive after the third dose with a median HA-IgG titer of 10.1 (interquartile range, 7.2-12.2) (sample/cut-off values [s/co]). In 45 (40-49) months, seropositivity decreased to 90% (46/51) and was attenuated to a median of 4.4 (2.3-6.5)s/co. Lower baseline B cell counts (p=0.049), lower anti-HA-IgG levels after the second dose (p=0.002), and lower anti-HA-IgG levels after the third dose (p=0.003) were associated with seronegativity. Anti-HA-IgG titers of vaccinated MSM-LWHIV may be attenuated; thus, additional immunizations should be considered.

Immunogenicity and safety of concomitant bivalent COVID-19 and quadrivalent influenza vaccination: implications of immune imprinting and interference

ObjectivesConcomitant COVID-19 and influenza vaccination would be an efficient strategy. Although the co-administration of monovalent COVID-19 and influenza vaccinations showed acceptable immunogenicity, it remains unknown whether the bivalent COVID-19 vaccine could intensify immune interference. We aimed to evaluate the immunogenicity and safety of concomitant BA.5-based bivalent COVID-19 and influenza vaccination. MethodsAn open-label, nonrandomized clinical trial was conducted for 154 age-matched and sex-matched healthy adults between October 2022 and December 2022. Participants received either a concomitant bivalent COVID-19 mRNA booster and quadrivalent influenza vaccination (group C) or separate vaccinations (group S) at least 4 weeks apart. Solicited and unsolicited adverse events were reported up to 6 months postvaccination. Immunogenicity was evaluated by anti-spike (S) IgG electrochemiluminescence immunoassay, focus reduction neutralization test, and hemagglutination inhibition assay. ResultsGroup C did not meet the noninferiority criteria for the seroconversion rates of anti-S IgG and neutralizing antibodies against the wild-type SARS-CoV-2 strain compared with group S (44.2% vs. 46.8%, difference of −2.6% [95% CI, −18 to 13.4]; 44.2% vs. 57.1%, difference of −13.0% [95% CI to −28.9 to 2.9]). However, group C showed a stronger postvaccination neutralizing antibody response against Omicron BA.5 (72.7% vs. 64.9%). Postvaccination geometric mean titers for SARS-CoV-2 and influenza strains were similar between groups, except for influenza B/Victoria. Most adverse events were mild and comparable between the study groups. DiscussionConcomitant administration of bivalent COVID-19 mRNA and quadrivalent influenza vaccines showed tolerable safety profiles and sufficient immunogenicity, particularly attenuating immune imprinting induced by previous ancestral vaccine strains.

Immunogenicity and safety of a live-attenuated varicella vaccine in a healthy population aged 13 years and older: A randomized, double-blind, controlled study

ObjectivesVaccines for prevention against varicella are important for adolescents and adults, who have an increased risk of severe varicella. This study aimed to evaluate the immunogenicity and safety of a two-dose immunization schedule of a live-attenuated varicella vaccine (VarV) manufactured by Sinovac (Dalian) in healthy adolescents and adults. MethodsA randomized, double-blind, controlled clinical trial was conducted in healthy population aged ≥ 13 years old in China. Participants in block 1 were randomly assigned (1:1) to receive two doses of either the test vaccine or an active control vaccine, administered 4, 6 or 8 weeks apart. Participants in block 2 were randomly assigned (2:1) to receive two doses of test vaccine or placebo, administered 10 weeks apart. The primary immunogenicity endpoint was the seroconversion rates and GMTs of varicella zoster virus (VZV) antibodies measured by fluorescent-antibody-to-membrane-antigen (FAMA) 4 weeks post-immunization. The primary safety endpoint was the incidence of adverse reactions within 4 weeks after each dose. ResultsA total of 2398 participants were enrolled. The seroconversion rates of VZV antibodies were 79.55 % in the test group and 76.41 % in the active control group respectively 4 weeks after two doses of pooled schedule, with the difference of 3.14 % (95 %CI: −0.69 %, 6.97 %). The GMTs were 1:162.07 and 1:160.04 respectively, with the ratio of 1.013 (95 %CI: 0.910, 1.127). Both the seroconversion rates and GMTs reached the prespecified non-inferiority criteria. Two-dose schedule with an interval of 10 weeks could also induce high immune responses, with a seroconversion rate of 83.22 % and a GMT of 1:160.38 in the test group. Safety profiles were similar among the test group, active control group and placebo group. ConclusionVarV, manufactured by Sinovac (Dalian), demonstrated higher immune response and better flexibility in the immunization schedule among heathy population aged 13 years and older, without increased safety risk.

2344. Clinical Profile and Immunologic Response from COVID-19 Vaccine Among People Living with HIV Enrolled in a Treatment Hub in the Philippines

Abstract Background SARS-CoV-2 has caused more than 1 million deaths worldwide. Several studies showed that People with HIV had higher rates of hospitalization and mortality with COVID-19 compared with people without HIV but data on serologic response to COVID-19 vaccine among People Living with HIV (PLHIV) is still limited. Methods A prospective cohort study on determination of serologic response to COVID-19 vaccine among completely vaccinated PLHIV enrolled in a treatment hub in the Philippines until December 31, 2021 was done. Baseline demographics were collected via chart review. History of COVID-19 infection was also asked during enrollment, on follow-up and at the end of 6 months after the 2nd dose of vaccination. Blood Extraction were done on enrollment and on follow-up visit to the treatment hub. All the specimen were processed using the SARS-CoV2 ( RocheElecsys Anti-SARS-CoV2 spike (S) protein assays. Results A total of 261 PLHIV who received vaccination from February 11, 2021 to December 29, 2021 were enrolled in the study. The participants received any of the following vaccine brands: CoronoVac/Sinovac (41%), Oxford-AstraZeneca (20.7%), Pfizer-BioNTech (21.5%), Moderna (14.2% and Janseen (2.7%). Univariate analysis showed that presence of opportunistic infection, HIV Viral load , Antiretroviral(ARV) Status, COVID-19 Vaccine brand were all significant predictors of antibody response. On multiple regression analysis, only the Vaccine Brand and Viral load remained significant. Sinovac gave a lower median antibody level and seroconversion rate as compared to other vaccine brands. HIV Viral load &amp;gt; 1000 copies/ml was predictive of lower antibody response. Conclusion In this study among PLHIV, the type of vaccine and HIV viral load were significant predictors of antibody response to COVID-19 Vaccine. Specifically, Sinovac COVID-19 Vaccine gave a lower Median SARS-CoV-2 IgG(S) Antibody and Seroconversion rate as compared to other Vaccine brands. HIV Viral load &amp;gt; 1000 copies/ml was predictive of lower antibody response to COVID-19 Vaccine . Overall, the antibody response peaked at 2-4 weeks after vaccination and decreases thereafter. Disclosures All Authors: No reported disclosures

Safety, Tolerability, and Immunogenicity of Measles and Rubella Vaccine Delivered with a High-Density Microarray Patch: Results from a Randomized, Partially Double-Blinded, Placebo-Controlled Phase I Clinical Trial

Microarray patches (MAPs) have the potential to be a safer, more acceptable, easier-to-use, and more cost-effective means for the administration of vaccines than injection by needle and syringe. Here, we report findings from a randomized, partially double-blinded, placebo-controlled Phase I trial using the Vaxxas high-density MAP (HD-MAP) to deliver a measles rubella (MR) vaccine. Healthy adults (N = 63, age 18–50 years) were randomly assigned 1:1:1:1 to four groups: uncoated (placebo) HD-MAPs, low-dose MR HD-MAPs (~3100 median cell-culture infectious dose [CCID50] measles, ~4300 CCID50 rubella); high-dose MR-HD-MAPs (~9300 CCID50 measles, ~12,900 CCID50 rubella); or a sub-cutaneous (SC) injection of an approved MR vaccine, MR-Vac (≥1000 CCID50 per virus). The MR vaccines were stable and remained viable on HD-MAPs when stored at 2–8 °C for at least 24 months. When MR HD-MAPs stored at 2–8 °C for 24 months were transferred to 40 °C for 3 days in a controlled temperature excursion, loss of potency was minimal, and MR HD-MAPs still met World Health Organisation (WHO) specifications. MR HD-MAP vaccination was safe and well-tolerated; any systemic or local adverse events (AEs) were mild or moderate. Similar levels of binding and neutralizing antibodies to measles and rubella were induced by low-dose and high-dose MR HD-MAPs and MR-Vac. The neutralizing antibody seroconversion rates on day 28 after vaccination for the low-dose HD-MAP, high-dose HD-MAP and MR-Vac groups were 37.5%, 18.8% and 35.7%, respectively, for measles, and 37.5%, 25.0% and 35.7%, respectively, for rubella. Most participants were seropositive for measles and rubella antibodies at baseline, which appeared to negatively impact the number of participants that seroconverted to vaccines delivered by either route. The data reported here suggest HD-MAPs could be a valuable means for delivering MR-vaccine to hard-to-reach populations and support further development. Clinical trial registry number: ACTRN12621000820808.

The humoral and cellular immune responses following booster vaccination with SARS-CoV-2 mRNA in people living with human immunodeficiency virus

IntroductionPeople living with human immunodeficiency virus (PLWH) have higher mortality rates from COVID-19 than those without HIV. Additionally, the seroconversion rate of antibodies following a second dose of SARS-CoV-2 vaccine is lower in PLWH than non-infected individuals, indicating the need for booster vaccination. Here, we evaluated the humoral and cellular immune responses to booster SARS-CoV-2 vaccination in PLWH. MethodsThe dynamics of anti-spike IgG titers and antigen-specific interferon (IFN)-γ levels to SARS-CoV-2 vaccination were assessed over a 6-month period following a third vaccination of 34 PLWH. ResultsAntibody titers for humoral immunity were 50 % lower at 24 weeks post-vaccination than those at 12 weeks. However, those at 24 weeks after the booster vaccination were approximately eight times higher than before. Regarding cellular immunity, IFN-γ levels at 24 weeks after the third vaccination were lower than those at 12 weeks, but nearly 90 % of participants maintained a cut-off value of ≥0.15 IU/mL. A comparison between two groups with CD4+ T lymphocytes counts of <500/μL or ≥500/μL exhibited no statistically significant differences in antibody or IFN-γ levels. However, in the group with CD4+ T lymphocyte counts of <500/μL, the rate of IFN-γ above the cut-off value at 24 weeks after the booster vaccination was lower than that of ≥500/μL. ConclusionAn immune response is expected in PLWH given successful antiretroviral therapy with booster SARS-CoV-2 vaccination. However, caution should be exercised for cases with low CD4+ T-lymphocyte counts. (240/250 words)

Safety and immunogenicity of the COVID-19 mRNA vaccine CS-2034: A randomized, double-blind, dose-exploration, placebo-controlled multicenter Phase I clinical trial in healthy Chinese adults

The novel coronavirus pneumonia (COVID-19) is an infectious disease caused by the infection of a novel coronavirus known as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which has resulted in millions of deaths. We aimed to evaluate the safety and immunogenicity of the COVID-19 mRNA vaccine (CS-2034, CanSino, Shanghai, China) in adults without COVID-19 infection from China. This is a multicenter Phase I clinical trial with a randomized, double-blinded, dose-exploration, placebo-controlled design. The trial recruited 40 seronegative participants aged 18-59 years who had neither received any COVID-19 vaccine nor been infected before. They were divided into a low-dose group (administered with either the CS-2034 vaccine containing 30μg of mRNA or a placebo of 0.3ml type 5 adenovirus vector) and a high-dose group (administered with either the CS-2034 vaccine containing 50μg of mRNA or a placebo of 0.5ml type 5 adenovirus vector). Participants were randomly assigned in a 3:1 ratio to receive either the mRNA vaccine or a placebo on days 0 and 21 according to a two-dose immunization schedule. The first six participants in each dosage group were assigned as sentinel subjects. Participants were sequentially enrolled in a dose-escalation manner from low to high dose and from sentinel to non-sentinel subjects. Blood samples were collected from all participants on the day before the first dose (Day 0), the day before the second dose (day 21), 14 days after the second dose (day 35), and 28 days after the second dose (day 49) to evaluate the immunogenicity of the CS-2034 vaccine. Participants were monitored for safety throughout the 28-day follow-up period, including solicited adverse events, unsolicited adverse events, adverse events of special interest (AESI), and medically attended adverse events (MAE). This report focuses solely on the safety and immunogenicity analysis of adult participants aged 18-59 years, while the long-term phase of the study is still ongoing. This study is registered at ClinicalTrials.gov, NCT05373485. During the period from May 17, 2022, to August 8, 2022, a total of 155 participants aged 18-59 years were screened for this study. Among them, 115 participants failed the screening process, and 40 participants were randomly enrolled (15 in the low-dose group, 15 in the high-dose group, and 10 in the placebo group). Throughout the 28-day follow-up period, the overall incidence of adverse reactions (related to vaccine administration) in the low-dose group, high-dose group, and placebo group was 93.33% (14/15), 100.00% (15/15), and 80.00% (8/10), respectively. There was a statistically significant difference in the incidence of local adverse reactions (soreness, pruritus, swelling at the injection site) among the low-dose group, high-dose group, and placebo group (P=0.002). All adverse reactions were mainly of severity grade 1 (mild) or 2 (moderate), and no adverse events of severity grade 4 or higher occurred. Based on the analysis of Spike protein Receptor Binding Domain (S-RBD) IgG antibodies against the BA.1 strain, the seroconversion rates of antibodies at day 21 after the first dose were 86.67%, 93.33%, and 0.00% in the low-dose group, high-dose group, and placebo group, respectively. The geometric mean titer (GMT) of antibodies was 61.2(95%CI 35.3-106.2), 55.4(95%CI 36.3-84.4), and 15.0(95%CI 15.0-15.0), and the geometric mean fold increase (GMI) was 4.08(95%CI 2.35-7.08), 3.69(95%CI 2.42-5.63), and 1.00(95%CI 1.00-1.00) for each group. At day 28 after the full vaccination, the seroconversion rates of antibodies were 100.00%, 93.33%, and 0.00%, and the GMT of antibodies was 810.0(95%CI 511.4-1283.0), 832.2(95%CI 368.1-1881.6), and 15.0(95%CI 15.0-15.0), and the GMI was 54.00(95%CI 34.09-85.53), 55.48(95%CI 24.54-125.44), and 1.00(95%CI 1.00-1.00) for each group, respectively. Based on the analysis of CD3+/CD4+ cell cytokine response, the percentages of IL-2+, IL-4+, IFN-γ+, and TNF-α+ cells increased after 14 days and 28 days of full vaccination in both the low-dose group and high-dose group. The increase was most pronounced in the high-dose group. At day 28 after the full vaccination, both the low-dose and the high-dose CS-2034 vaccine were able to induce the production of high titers of S-RBD IgG antibodies against the BA.1 strain. Adverse reactions in the low-dose and high-dose groups were mainly of severity grade 1 or 2, and no trial-limiting safety concerns were identified. These findings support further development of this vaccine.

Immunogenicity and safety of HavisureTM vaccine developed by Human Biologicals Institute in healthy subjects of 12 months to 49 years of age: A phase II/III, randomized, single blind, non-inferiority study

BackgroundHepatitis A is an inflammation of the liver caused by the hepatitis A virus (HAV). It is transmitted mainly because of poor personal hygiene via the faecal/oral route through ingestion of contaminated food or water or through the direct contact with an infectious person. Though most of the infected individuals recover from the infection, a few may develop fatal fulminant hepatitis. In this randomized, multicenter study, immunogenicity and safety of Havisure™ vaccine of Human Biologicals Institute was compared with Havrix® vaccine. MethodsThe study was carried out in 528 eligible healthy subjects, in two age groups across eight centres in India. Group A included subjects of 19–49 years and Group B subjects of 12 months to below 19 years of age. All subjects received two doses of either Havisure™ vaccine or Havrix® vaccine as per randomization at six months interval. Blood samples for antibody titre estimation were collected before vaccination and 4–6 weeks after 2nd dose of vaccination. Immunogenicity was assessed by estimating seroconversion rate, seroprotection rate, and geometric mean titres of antibodies. Safety was evaluated by collection and analysis of data on solicited and unsolicited adverse events. ResultsOf 528 enrolled subjects, 493 subjects completed the study. There was 100% seroconversion and seroprotection in both the vaccine arms. There was no statistical difference in the geometric mean titres between the two vaccine arms. Pain and swelling at the site of injection were the most common local adverse events whereas fever and headache were the most common systemic adverse events observed in both vaccine arms. No serious adverse event was reported in the study. ConclusionThe study results indicate that the Havisure™ vaccine is immunogenic and safe when administered to healthy subjects of 12 months to 49 years of age, and is non-inferior to Havrix® Vaccine.

Immunogenicity and safety assessment of a SARS-CoV-2 recombinant spike RBD protein vaccine (Abdala) in paediatric ages 3–18 years old: a double-blinded, multicentre, randomised, phase 1/2 clinical trial (ISMAELILLO study)

COVID-19 in paediatric ages could result in hospitalizations and death. In addition, excluding children from vaccination could turn them into reservoirs of the SARS-COV-2. Safe and effective COVID-19 vaccines are urgently needed for large-scale paediatric vaccination. ISMAELILLO study aimed to evaluate safety and immunogenicity of two strengths of a new recombinant receptor-binding domain (RBD) protein vaccine (Abdala) in paediatric population. A double-blinded, multicentre, randomised, phase 1/2 clinical trial was conducted in nine polyclinics in the province of Camagüey, Cuba. Healthy children and adolescents were stratified according to age (3-11 years old, or 12-18 years old) and they were randomly assigned (1:1; block size four) in two dosage level groups of vaccine to receive three intramuscular doses of 25μg or 50μg of RBD, 14 days apart. Main safety endpoint was analyzed as the percentage of serious adverse reactions during vaccination up to 28 days after the third dose (Day 56) in participants who received at least one dose vaccination. The primary immunogenicity endpoint assessed was seroconversion rate of anti-RBD IgG antibody at day 56. The immunogenicity outcomes were assessed in the per-protocol population. This trial is registered with Cuban Public Registry of Clinical Trials, RPCEC00000381. Between July 15, 2021, and August 16, 2021, 644 paediatric subjects were screened, of whom 592 were enrolled after verifying that they met the selection criteria: firstly 88 were included in Phase 1 of the study and 504 who completed Phase 2. The vaccine was well tolerated. Injection site pain was the most frequently reported local event (143 [8·4%] of 1707 total doses applied), taking place in 66/851 (7·8%) in the 25μg group and in 77/856 (9·0%) in the 50μg. The most common systemic adverse event (AE) was headache: 23/851 (2·7%) in the 25μg group and 19/856 (2·2%) in the 50μg. Reactogenicity was mild or moderate in severity, represented in 75% of cases by local symptoms, completely resolved in the first 24-48h. Twenty-eight days after the third dose, seroconversion anti-RBD IgG were observed in 98·2% of the children and adolescents (231/234) for the 50μg group and 98·7% (224/228) for the 25μg group without differences between both strength. The specific IgG antibody geometric mean titres (GMT) showed higher titres between participants who received Abdala 50μg (231·3; 95% CI 222·6-240·4) compared to those who received 25μg (126·7; 95% CI 121·9-131·7). The mean ACE2 inhibition %, were 59·4% for 25μg, and for 50μg, 72·9% (p<0·01). Both strength elicited neutralising activity against the SARS-CoV-2, specifically (18·3; 95% CI 14·7-22·78) for Abdala 25μg and (36·4; 95% CI 30·26-43·8) for 50μg to the selected sample analyzed. Abdala vaccine was safe and well tolerated at both antigenic strength levels tested in participants aged between 3 and 18 years. Regarding immunogenicity, Abdala Vaccine stimulated the production of specific IgG antibodies against the RBD of SARS-CoV-2 as well as the production of ACE2 inhibition titres and neutralising antibodies (Nab) in children and adolescents. Centre for Genetic Engineering and Biotechnology (CIGB), Havana, Cuba.

Comparison of Humoral Antibody Responses and Seroconversion Rates between Two Homologous ChAdOx1 nCoV-19 and mRNA-1273 Vaccination in Patients Undergoing Maintenance Hemodialysis.

Hemodialysis patients are at an increased risk of SARS-CoV-2 infection and are excluded from preauthorization COVID-19 vaccine trials; therefore, their immunogenicity is uncertain. To compare the antibody responses to homologous ChAdOx1 and mRNA-1273 SARS-CoV-2 vaccination in hemodialysis patients, 103 age- and sex-matched hemodialysis patients with two homologous prime-boost vaccinations were recruited to detect anti-receptor-binding domain (RBD) IgG levels and seroconversion rates (SCRs) 14 days after a prime dose (PD14), before and 28 days after a boost dose (pre-BD0 and BD28). Both mRNA-1273 and ChAdOx1 vaccinations elicited immunogenicity in study subjects, and the former induced higher anti-RBD IgG levels than the latter. The SCRs of both groups increased over time and varied widely from 1.82% to 97.92%, and were significantly different at PD14 and pre-BD0 regardless of different thresholds. At BD28, the SCRs of the ChAdOx1 group and the mRNA-1273 group were comparable using a threshold ≥ 7.1 BAU/mL (93.96% vs. 97.92%) and a threshold ≥ 17 BAU/mL (92.73% vs. 97.92%), respectively, but they were significantly different using a threshold ≥ 20.2% of convalescent serum anti-RBD levels (52.73% vs. 95.83%). The seroconversion (≥20.2% of convalescent level) at BD28 was associated with mRNA-1273 vaccination after being adjusted for age, sex, body mass index, and the presence of solicited reactogenicity after a prime vaccination. Our prospective, observational cohort indicates that a full prime-boost mRNA-1273 vaccination is likely to provide higher immune protection in hemodialysis patients compared to ChAdOx1, and this population with a prime-boost ChAdOx1 vaccination should be prioritized for a third dose.

Immunogenicity persistence of hepatitis A vaccines Healive® and Havrix® among children:15 years follow-up and long-term prediction

ABSTRACT Healive® was the only Chinese WHO-prequalified inactivated vaccine for the hepatitis A virus, which has been widely used in national immunization programs in China. Long-term follow-up studies are needed to estimate the persistence of vaccine-induced antibody levels and the necessity for booster vaccines. During the trial, geometric mean concentrations (GMCs) and seroconversion rates (SRs) of anti-HAV antibodies were compared based on two different inactivated hepatitis A vaccines, Healive® and Havrix®. Four hundred children were randomly assigned to receive two doses of Healive® or Havrix® at 0 and 6 months. The current study assessed antibody persistence for both vaccines 15 years post-immunization. A mixed linear model was used to predict long-term antibody persistence. The GMCs were significantly higher for Healive® compared to Havrix® at 1, 6, 7, 66, 138 months (P < .001) and 186 months (P = .004 < .05) post-vaccination. Healive® and Havrix® reached a GMC of 164.8 mIU/ml and 105.7 mIU/ml post-15 years of vaccination, respectively. The seroconversion rates of both vaccines showed no statistically significant differences (97.9% for Healive® and 94.7% for Havrix®, P = .20). The prediction showed that Healive® would provide protection for a minimum of 30 years following immunization, with a lower limit of the 95% confidence intervals for GMCs greater than 20mIU/mL. Compared to Havrix®, the vaccine Healive® showed a stronger protective effect and better persistence among children at 15 years post-full immunization. Prediction indicated at least 30 years of antibody persistence for Healive® and at least 25 years for Havrix®.

The effectiveness of the first dose COVID-19 booster vs. full vaccination to prevent SARS-CoV-2 infection and severe COVID-19 clinical event: a meta-analysis and systematic review of longitudinal studies.

The effectiveness of full Coronavirus Disease 2019 (COVID-19) vaccination against COVID-19 wanes over time. This study aimed to synthesize the clinical effectiveness of the first dose of COVID-19 booster by comparing it to the full vaccination. Studies in PubMed, Web of Science, Embase, and clinical trials databases were searched from 1 January 2021 to 10 September 2022. Studies were eligible if they comprised general adult participants who were not ever or currently infected with SARS-CoV-2, did not have impaired immunity or immunosuppression, and did not have severe diseases. The seroconversion rate of antibodies to S and S subunits and antibody titers of SARS-CoV-2, frequency, phenotype of specific T and B cells, and clinical events involving confirmed infection, admission to the intensive care unit (ICU), and death were compared between the first booster dose of COVID-19 vaccination group and full vaccination group. The DerSimonian and Laird random effects models were used to estimate the pooled risk ratios (RRs) and corresponding 95% confidence intervals (CIs) for the outcomes of clinical interest. While a qualitative description was mainly used to compare the immunogenicity between the first booster dose of COVID-19 vaccination group and full vaccination group. Sensitivity analysis was used to deal with heterogenicity. Of the 10,173 records identified, 10 studies were included for analysis. The first dose COVID-19 booster vaccine could induce higher seroconversion rates of antibodies against various SAS-CoV-2 fragments, higher neutralization antibody titers against various SARS-CoV-2 variants, and robust cellular immune response compared to the full vaccination. The risk of SARS-CoV-2 infection, the risk of admission to the ICU, and the risk of death were all higher in the non-booster group than those in the booster group, with RRs of 9.45 (95% CI 3.22-27.79; total evaluated population 12,422,454 vs. 8,441,368; I2 = 100%), 14.75 (95% CI 4.07-53.46; total evaluated population 12,048,224 vs. 7,291,644; I2 = 91%), and 13.63 (95% CI 4.72-39.36; total evaluated population 12,385,960 vs. 8,297,037; I2 = 85%), respectively. A homogenous or heterogeneous booster COVID-19 vaccination could elicit strong humoral and cellular immune responses to SARS-CoV-2. Furthermore, it could significantly reduce the risk of SARS-CoV-2 infection and severe COVID-19 clinical events on top of two doses. Future studies are needed to investigate the long-term clinical effectiveness of the first booster dose of the COVID-19 vaccine and compare the effectiveness between homogenous and heterogeneous booster COVID-19 vaccination. https://inplasy.com/inplasy-2022-11-0114/, identifier: INPLASY2022110114.

Dynamics of CD4+ T-Cells and Neutralizing Antibody Responses to Three Consecutive Doses of Inactivated COVID-19 Vaccines in PLWH.

Comprehensive characterization of safety and immune responses to vaccines is crucial for the prevention and treatment of COVID-19 among people living with HIV (PLWH). This study aimed to investigate the dynamic changes in SARS-CoV-2-specific CD4+ T-cell subsets and neutralizing antibody after three consecutive doses of inactivated COVID-19 vaccines (BBIBP-CorV) among PLWH. The blood samples were collected from 165 PLWH, including 66 PLWH in the 3-month interval between the second and third dose (cohort 1) and 99 PLWH in the 5-month interval (cohort 2). Blood collection for immunogenicity analysis was performed at 1-month post-2nd vaccination, pre-3rd vaccination, and within 2-month post-3rd vaccination. Wilcoxon matched-pairs signed-rank test was applied to compare the SARS-CoV-2-specific CD4+ T cell subsets and neutralizing antibody level at different time points. The relationship among CD4+ T-cells, Tregs subpopulations and SARS-CoV-2-specific neutralizing antibody level were evaluated with Spearman non-parametriccorrelationtest. No serious adverse reactions were found among PLWH. After two-dose or three-dose inactivated COVID-19 vaccination, the absolute counts of CD4+ T-cells and Tregs subpopulations (CD4+CD25HighCD127Low Tregs, CD45RA+ rTregs and CD45RO+ eTregs) increased in two cohorts. Satisfactory SARS-CoV-2-specific neutralizing antibody responses to the third-dose vaccination were found in two cohorts, including significantly enhanced neutralizing antibody level and high neutralizing antibody seroconversion rate. In addition, SARS-CoV-2-specific neutralizing antibody level were positively associated with the absolute counts of CD4+ T-cells and Tregs subpopulations as well as the frequency of CD45RO+ eTregs in PLWH after three doses of vaccinations. The three doses of inactivated COVID-19 vaccination were both safe and effective to increase SARS-CoV-2-specific CD4+ T-cells and neutralizing antibody in two PLWH cohorts with different inoculation intervals.

Safety and Immunogenicity of Enterovirus 71 Vaccine (Vero Cell) Administered Simultaneously with Trivalent Split-Virion Influenza Vaccine in Infants Aged 6-7 Months: A Phase 4, Randomized, Controlled Trial.

Objective: To assess the immunogenicity and safety of the enterovirus 71 vaccine (Vero cell) (EV71 vaccine) and trivalent split-virion influenza vaccine (IIV3). Methods: Healthy infants aged 6-7 months were recruited from Zhejiang Province, Henan Province, and Guizhou Province and randomly assigned to the simultaneous vaccination group, EV71 group, and IIV3 group at a ratio of 1:1:1. Then, 3 mL blood samples were collected before vaccination and 28 days after the second dose of vaccine. Cytopathic effect inhibition assay was used to detect EV71 neutralization antibody, and cytopathic effect inhibition assay was used to detect influenza virus antibody. Results: A total of 378 infants were enrolled and received the first dose of vaccine and were included in the safety analysis, and 350 infants were involved in the immunogenicity analysis. The adverse events rates were 31.75%, 28.57%, and 34.13% in the simultaneous vaccination group, EV71 group, and IIV3 group (p > 0.05), respectively. No vaccine-related serious adverse events were reported. After two doses of EV71 vaccine, the seroconversion rates of EV71 neutralizing antibody were 98.26% and 97.37% in the simultaneous vaccination group and the EV71 group, respectively. After two doses of IIV3, the simultaneous vaccination group and the IIV3 group, respectively, had seroconversion rates of 80.00% and 86.78% for H1N1 antibody, 99.13% and 98.35% for H3N2 antibody, and 76.52% and 80.99% for B antibody. There was no statistically significant difference in the seroconversion rates of influenza virus antibodies between groups (p > 0.05). Conclusions: The coadministration of EV71 vaccine and IIV3 has good safety and immunogenicity in infants aged 6-7 months.

Humoral immune response to inactivated COVID-19 vaccination at the 3rd month among people living with HIV

BackgroundResearch on the immune response to inactivated COVID-19 vaccination among people living with HIV (PLWH) is limited, especially among those with low CD4+ T lymphocyte (CD4 cell) count. This prospective cohort study aimed to assess the humoral immune response to inactivated COVID-19 vaccination among PLWH compared to HIV negative controls (HNCs) and to determine the impact of CD4 cell count on vaccine response among PLWH.MethodsThe neutralizing antibodies (nAbs) and the specific IgM and IgG-binding antibody responses to the inactivated COVID-19 vaccine at the third month after the second dose of inactivated COVID-19 vaccination were measured among 138 PLWH and 35 HNCs. Multivariable logistic regression and multiple linear regression models were conducted to identify factors associated with the seroconversion rate of antibodies and the magnitude of anti-SARS-CoV-2 antibody titers, respectively.ResultsAt the end of the third month after two doses of vaccination, the seroconversion rates of IgG were comparable between PLWH (44.9%; 95% CI 36.5–53.3%) and HNCs (60.0%; 95% CI 42.9–77.1%), respectively. The median titers and seroconversion rate of nAbs among PLWH were 0.57 (IQR: 0.30–1.11) log10 BAU/mL and 29.0% (95% CI 21.3–36.8%), respectively, both lower than those in HNCs (P < 0.05). After adjusting for age, sex, comorbidities, and CD4 cell count, the titers and seroconversion rate of nAbs were comparable between PLWH and HNCs (P > 0.05). Multivariable regression analyses showed that CD4 cell count < 200/μL was independently associated with lower titers and seroconversion rate of nAbs among PLWH (P < 0.05). A positive correlation was observed between the CD4 cell count and nAbs titers in PLWH (Spearman's ρ = 0.25, P = 0.0034).ConclusionOur study concluded that the immune response to inactivated COVID-19 vaccination among PLWH was independently associated with CD4 cell count, PLWH with lower CD4 cell count showed a weaker humoral immune response, especially those with CD4 cell count < 200/μL. This finding suggests that expanding COVID-19 vaccination coverage among PLWH is impendency. In addition, aggressive ART should be carried out for PLWH, especially for those with low CD4 cell count, to improve the immune response to vaccines.