Transcriptional and Immunologic Correlates of Response to Pandemic Influenza Vaccine in Aviremic, HIV-Infected Children

People living with HIV (PWH) often exhibit poor responses to influenza vaccination despite effective combination anti-retroviral (ART) mediated viral suppression. There exists a paucity of data in identifying immune correlates of influenza vaccine response in context of HIV infection that would be useful in improving its efficacy in PWH, especially in younger individuals. Transcriptomic data were obtained by microarray from whole blood isolated from aviremic pediatric and adolescent HIV-infected individuals (4-25 yrs) given two doses of Novartis/H1N1 09 vaccine during the pandemic H1N1 influenza outbreak. Supervised clustering and gene set enrichment identified contrasts between individuals exhibiting high and low antibody responses to vaccination. High responders exhibited hemagglutination inhibition antibody titers >1:40 post-first dose and 4-fold increase over baseline. Baseline molecular profiles indicated increased gene expression in metabolic stress pathways in low responders compared to high responders. Inflammation-related and interferon-inducible gene expression pathways were higher in low responders 3 wks post-vaccination. The broad age range and developmental stage of participants in this study prompted additional analysis by age group (e.g. <13yrs and ≥13yrs). This analysis revealed differential enrichment of gene pathways before and after vaccination in the two age groups. Notably, CXCR5, a homing marker expressed on T follicular helper (Tfh) cells, was enriched in high responders (>13yrs) following vaccination which was accompanied by peripheral Tfh expansion. Our results comprise a valuable resource of immune correlates of vaccine response to pandemic influenza in HIV infected children that may be used to identify favorable targets for improved vaccine design in different age groups.

Perspectives on RNA Vaccine Candidates for COVID-19

With the current outbreak caused by SARS-CoV-2, vaccination is acclaimed as a public health care priority. Rapid genetic sequencing of SARS-CoV-2 has triggered the scientific community to search for effective vaccines. Collaborative approaches from research institutes and biotech companies have acknowledged the use of viral proteins as potential vaccine candidates against COVID-19. Nucleic acid (DNA or RNA) vaccines are considered the next generation vaccines as they can be rapidly designed to encode any desirable viral sequence including the highly conserved antigen sequences. RNA vaccines being less prone to host genome integration (cons of DNA vaccines) and anti-vector immunity (a compromising factor of viral vectors) offer great potential as front-runners for universal COVID-19 vaccine. The proof of concept for RNA-based vaccines has already been proven in humans, and the prospects for commercialization are very encouraging as well. With the emergence of COVID-19, mRNA-1273, an mRNA vaccine developed by Moderna, Inc. was the first to enter human trials, with the first volunteer receiving the dose within 10 weeks after SARS-CoV-2 genetic sequencing. The recent interest in mRNA vaccines has been fueled by the state of the art technologies that enhance mRNA stability and improve vaccine delivery. Interestingly, as per the "Draft landscape of COVID-19 candidate vaccines" published by the World Health Organization (WHO) on December 29, 2020, seven potential RNA based COVID-19 vaccines are in different stages of clinical trials; of them, two candidates already received emergency use authorization, and another 22 potential candidates are undergoing pre-clinical investigations. This review will shed light on the rationality of RNA as a platform for vaccine development against COVID-19, highlighting the possible pros and cons, lessons learned from the past, and the future prospects.

Vaccine Hesitancy: Characteristics of the Refusal of Childhood Vaccination in a Peruvian Population

Understanding the determinants of vaccine hesitancy is paramount to reinstate confidence in immunizations. The objective of this investigation was to explore the characteristics of the vaccination decision-making process that may result in the refusal of childhood immunization in Peru, during February-June 2020. A descriptive, cross-sectional study involving telephone interviews was executed in Peru. The Parents Attitudes about Childhood Vaccines (PACV) survey was used. A demographic analysis was done, followed by an unadjusted exploratory subgroup analysis. Out of 552 subjects, 9.8% were considered vaccine hesitant, 70.3% had purposively delayed vaccination, 88.4% thought fewer vaccines were better and 52.2% were concerned about vaccine safety. The level of hesitancy was inversely proportional to the level of education and the number of children at home. Mothers and subjects aged ≤29 years showed a greater level of vaccine hesitancy. This population displays a vaccine-hesitant conduct. Vaccine safety and the number of vaccines to administer are important determining factors. This behavior could be influenced by variables such as level of education, number of children at home, parental relationship, and age. These results help understand local vaccination behaviors. More studies are encouraged to confirm and validate these findings.

A global pandemic in the time of viral memes: COVID-19 vaccine misinformation and disinformation on TikTok

Misinformation and disinformation regarding COVID-19 and vaccination against it may be contributing to vaccine hesitancy. Social media outlets have reportedly made efforts to limit false information yet untruths related to COVID-19 persist online. The purpose of this study was to describe the content on COVID-19 vaccination on TikTok, an emerging social media platform. One-hundred trending videos were identified from the hashtag #covidvaccine and were coded for content. Collectively, these videos garnered over 35 million views. The coding category with the highest number of videos was "Discouraged a Vaccine" (n = 38), followed by "Encouraged a Vaccine" (n = 36). While only 36 videos encouraged a vaccine, these videos garnered over 50% of the total cumulative views and just under 50% of the total likes; the 38 videos that discouraged a vaccine garnered 39.6% of the total cumulative views, 44.3% of likes, and 47.4% of comments. Of the 38 videos discouraging the vaccine, 25 (65.79%) showed a parody of an adverse reaction and, collectively, received 71.07% of the total views among videos in this category. Twenty-two of these 38 videos (57.89%) falsely conveyed that a vaccine was available, as they were not at the time of the study. Anti-vaccination messaging may undermine efforts to ensure widespread uptake of the various COVID-19 vaccines, particularly for young people who are more likely than other age cohorts to use TikTok.

Infectious laryngotracheitis: Etiology, epidemiology, pathobiology, and advances in diagnosis and control - a comprehensive review

Infectious laryngotracheitis (ILT) is a highly contagious upper respiratory tract disease of chicken caused by a Gallid herpesvirus 1 (GaHV-1) belonging to the genus Iltovirus, and subfamily Alphaherpesvirinae within Herpesviridae family. The disease is characterized by conjunctivitis, sinusitis, oculo-nasal discharge, respiratory distress, bloody mucus, swollen orbital sinuses, high morbidity, considerable mortality and decreased egg production. It is well established in highly dense poultry producing areas of the world due to characteristic latency and carrier status of the virus. Co-infections with other respiratory pathogens and environmental factors adversely affect the respiratory system and prolong the course of the disease. Latently infected chickens are the primary source of ILT virus (ILTV) outbreaks irrespective of vaccination. Apart from conventional diagnostic methods including isolation and identification of ILTV, serological detection, advanced biotechnological tools such as PCR, quantitative real-time PCR, next generation sequencing, and others are being used in accurate diagnosis and epidemiological studies of ILTV. Vaccination is followed with the use of conventional vaccines including modified live attenuated ILTV vaccines, and advanced recombinant vector vaccines expressing different ILTV glycoproteins, but still these candidates frequently fail to reduce challenge virus shedding. Some herbal components have proved to be beneficial in reducing the severity of the clinical disease. The present review discusses ILT with respect to its current status, virus characteristics, epidemiology, transmission, pathobiology, and advances in diagnosis, vaccination and control strategies to counter this important disease of poultry.

Bovine Immune Response to Vaccination and Infection with Leptospira borgpetersenii Serovar Hardjo

This study examined the humoral and cellular response of cattle vaccinated with two commercial leptospiral vaccines, Leptavoid and Spirovac, and a novel bacterin vaccine using Seppic Montanide oil emulsion adjuvant. Vaccination was followed by experimental challenge. All vaccinated cattle were protected from colonization of the kidney and shedding of Leptospira in urine, as detected by culture and immunofluorescence assay. Agglutinating antibody titers were detected in vaccinated cattle at 4 weeks following vaccination, with small anamnestic response detected following experimental challenge. Only animals vaccinated with the oil emulsion-adjuvanted bacterin produced significant IgG2 titers following vaccination, and nonvaccinated animals produced serum IgA titers after experimental challenge. CD4⁺ and γδ T cells from vaccinated cattle proliferated when cultured with antigen ex vivo. Cellular responses included a marked proliferation of γδ T cells immediately following experimental challenge in vaccinated cattle and release of gamma interferon (IFN-γ), interleukin 17a (IL-17a), and IL-12p40 from stimulated cells. Proliferative and cytokine responses were found not just in peripheral mononuclear cells but also in lymphocytes isolated from renal lymph nodes at 10 weeks following experimental challenge. Overall, effects of leptospirosis vaccination and infection were subtle, resulting in only modest activation of CD4⁺ and γδ T cells. The use of Seppic Montanide oil emulsion adjuvants may shorten the initiation of response to vaccination, which could be useful during outbreaks or in areas where leptospirosis is endemic.

IMPORTANCE Leptospirosis is an underdiagnosed, underreported zoonotic disease of which domestic livestock can be carriers. As a reservoir host for Leptospira borgpetersenii serovar Hardjo, cattle may present with reproductive issues, including abortion, birth of weak or infected calves, or failure to breed. Despite years of study and the availability of commercial vaccines, detailed analysis of the bovine immune response to vaccination and Leptospira challenge is lacking. This study evaluated immunologic responses to two efficacious commercial vaccines and a novel bacterin vaccine using an adjuvant chosen for enhanced cellular immune responses. Antigen-specific responsive CD4 and γδ T cells were detected following vaccination and were associated with release of inflammatory cytokines IFN-γ and IL-17a after stimulation. CD4 and γδ cells increased in the first week after infection and, combined with serum antibody, may play a role in clearance of bacteria from the blood and resident tissues. Additionally, these antigen-reactive T cells were found in the regional lymph nodes following infection, indicating that memory responses may not be circulating but are still present in regional lymph nodes. The information gained in this study expands knowledge of bovine immune response to leptospirosis vaccines and infection. The use of oil emulsion adjuvants may enhance early immune responses to leptospiral bacterins, which could be useful in outbreaks or situations where leptospirosis is endemic.

Advances in vaccine development for human trichuriasis

Trichuriasis known as whipworm infection caused by Trichuris trichiura, is a highly prevalent soil-transmitted helminthiasis in low- and middle-income countries located in tropical and subtropical areas and affecting approximately 360 million people. Children typically harbour the largest burden of T. trichiura and they are usually co-infected with other soil-transmitted helminth (STH), including Ascaris lumbricoides and hookworm. The consequences of trichuriasis, such as malnutrition and physical and cognitive growth restriction, lead to a massive health burden in endemic regions. Despite the implementation of mass drug administration of anthelminthic treatment to school-age children, T. trichiura infection remains challenging to control due to the low efficacy of current drugs as well as high rates of post-treatment re-infection. Thus, the development of a vaccine that would induce protective immunity and reduce infection rate or community faecal egg output is essential. Hurdles for human whipworm vaccine development include the lack of suitable vaccine antigen targets and animal models for human T. trichiura infection. Instead, rodent whipworm T. muris infected mouse models serve as a major surrogate for testing immunogenicity and efficacy of vaccine candidates. In this review, we summarize recent advances in animal models for T. trichiura antigen discovery and testing of vaccine candidates, while providing an overall view of the current status of T. trichiura vaccine development.

Virus vaccines: proteins prefer prolines

Most viral vaccines are based on inducing neutralizing antibodies (NAbs) against the virus envelope or spike glycoproteins. Many viral surface proteins exist as trimers that transition from a pre-fusion state when key NAb epitopes are exposed to a post-fusion form in which the potential for virus-cell fusion no longer exists. For optimal vaccine performance, these viral proteins are often engineered to enhance stability and presentation of these NAb epitopes. The method involves the structure-guided introduction of proline residues at key positions that maintain the trimer in the pre-fusion configuration. We review how this technique emerged during HIV-1 Env vaccine development and its subsequent wider application to other viral vaccines including SARS-CoV-2.

Next-Generation Influenza HA Immunogens and Adjuvants in Pursuit of a Broadly Protective Vaccine

Influenza virus, a highly mutable respiratory pathogen, causes significant disease nearly every year. Current vaccines are designed to protect against circulating influenza strains of a given season. However, mismatches between vaccine strains and circulating strains, as well as inferior vaccine effectiveness in immunodeficient populations, represent major obstacles. In an effort to expand the breadth of protection elicited by influenza vaccination, one of the major surface glycoproteins, hemagglutinin (HA), has been modified to develop immunogens that display conserved regions from multiple viruses or elicit a highly polyclonal antibody response to broaden protection. These approaches, which target either the head or the stalk domain of HA, or both domains, have shown promise in recent preclinical and clinical studies. Furthermore, the role of adjuvants in bolstering the robustness of the humoral response has been studied, and their effects on the vaccine-elicited antibody repertoire are currently being investigated. This review will discuss the progress made in the universal influenza vaccine field with respect to influenza A viruses from the perspectives of both antigen and adjuvant, with a focus on the elicitation of broadly neutralizing antibodies.

Phase I study of a multitargeted recombinant Ad5 PSA/MUC-1/brachyury-based immunotherapy vaccine in patients with metastatic castration-resistant prostate cancer (mCRPC)

Background

Antitumor vaccines targeting tumor-associated antigens (TAAs) can generate antitumor immune response. A novel vaccine platform using adenovirus 5 (Ad5) vectors [E1–, E2b–] targeting three TAAs—prostate-specific antigen (PSA), brachyury, and MUC-1—has been developed. Both brachyury and the C-terminus of MUC-1 are overexpressed in metastatic castration-resistant prostate cancer (mCRPC) and have been shown to play an important role in resistance to chemotherapy, epithelial–mesenchymal transition, and metastasis. The transgenes for PSA, brachyury, and MUC-1 all contain epitope modifications for the expression of CD8+ T-cell enhancer agonist epitopes. We report here the first-in-human trial of this vaccine platform.

Methods

Patients with mCRPC were given concurrently three vaccines targeting PSA, brachyury, and MUC-1 at 5×10¹¹ viral particles (VP) each, subcutaneously every 3 weeks for a maximum of three doses (dose de-escalation cohort), followed by a booster vaccine every 8 weeks for 1 year (dose-expansion cohort only). The primary objective was to determine the safety and the recommended phase II dose. Immune assays and clinical responses were evaluated.

Results

Eighteen patients with mCRPC were enrolled between July 2018 and September 2019 and received at least one vaccination. Median PSA was 25.58 ng/mL (range, 0.65–1006 ng/mL). The vaccine was tolerable and safe, and no grade >3 treatment-related adverse events or dose-limiting toxicities (DLTs) were observed. One patient had a partial response, while five patients had confirmed PSA decline and five had stable disease for >6 months. Median progression-free survival was 22 weeks (95% CI: 19.1 to 34). Seventeen (100%) of 17 patients mounted T-cell responses to at least one TAA, whereras 8 (47%) of 17 patients mounted immune responses to all three TAAs. Multifunctional T-cell responses to PSA, MUC-1, and brachyury were also detected after vaccination in the majority of the patients.

Conclusions

Ad5 PSA/MUC-1/brachyury vaccine is well tolerated. The primary end points were met and there were no DLTs. The recommended phase II dose is 5×10¹¹ VP. The vaccine demonstrated clinical activity, including one partial response and confirmed PSA responses in five patients. Three patients with prolonged PSA responses received palliative radiation therapy. Further research is needed to evaluate the clinical benefit and immunogenicity of this vaccine in combination with other immuno-oncology agents and/or palliative radiation therapy.

Trial registration number

NCT03481816.

A Vaccine Strain of the A/ASIA/Sea-97 Lineage of Foot-and-Mouth Disease Virus with a Single Amino Acid Substitution in the P1 Region That Is Adapted to Suspension Culture Provides High Immunogenicity

There are seven viral serotypes of foot-and-mouth disease virus (FMDV): A, O, C, Asia 1, and Southern African Territories 1, 2, and 3 (SAT 1–3). Unlike serotype O FMDV vaccine strains, vaccine strains of serotype A FMDV do not provide broad-range cross-reactivity in serological matching tests with field isolates. Therefore, the topotype/lineage vaccine strain circulating in many countries and a highly immunogenic strain might be advantageous to control serotype A FMDV. We developed a new vaccine strain, A/SKR/Yeoncheon/2017 (A-1), which belongs to the A/ASIA/Sea-97 lineage that frequently occurs in Asian countries. Using virus plaque purification, we selected a vaccine virus with high antigen productivity and the lowest numbers of P1 mutations among cell-adapted virus populations. The A/SKR/Yeoncheon/2017 (A-1) vaccine strain has a single amino acid mutation, VP2 E82K, in the P1 region, and it is perfectly adapted to suspension culture. The A/SKR/Yeoncheon/2017 (A-1) experimental vaccine conferred high immunogenicity in pigs. The vaccine strain was serologically matched with various field isolates in two-dimensional virus neutralization tests using bovine serum. Vaccinated mice were protected against an A/MAY/97 virus that was serologically mismatched with the vaccine strain. Thus, A/SKR/Yeoncheon/2017 (A-1) might be a promising vaccine candidate for protection against the emerging FMDV serotype A in Asia.

The Interplay between CD27dull and CD27bright B Cells Ensures the Flexibility, Stability, and Resilience of Human B Cell Memory

Memory B cells (MBCs) epitomize the adaptation of the immune system to the environment. We identify two MBC subsets in peripheral blood, CD27^dull and CD27^bright MBCs, whose frequency changes with age. Heavy chain variable region (VH) usage, somatic mutation frequency replacement-to-silent ratio, and CDR3 property changes, reflecting consecutive selection of highly antigen-specific, low cross-reactive antibody variants, all demonstrate that CD27^dull and CD27^bright MBCs represent sequential MBC developmental stages, and stringent antigen-driven pressure selects CD27^dull into the CD27^bright MBC pool. Dynamics of human MBCs are exploited in pregnancy, when 50% of maternal MBCs are lost and CD27^dull MBCs transit to the more differentiated CD27^bright stage. In the postpartum period, the maternal MBC pool is replenished by the expansion of persistent CD27^dull clones. Thus, the stability and flexibility of human B cell memory is ensured by CD27^dull MBCs that expand and differentiate in response to change.

Applications of Melanin and Melanin-Like Nanoparticles in Cancer Therapy: A Review of Recent Advances

Thanks to the growing knowledge about cancers and their interactions with the immune system, a huge number of therapeutic cancer vaccines have been developed in the past two decades. Despite encouraging results in pre-clinical models, cancer vaccines have not yet achieved significant clinical efficacy. Several factors may contribute to such poor results, including the difficulty of triggering a strong immune response and the immunosuppressive tumor microenvironment. Many strategies are currently being explored. Different types of adjuvants have been incorporated into vaccine formulations to improve their efficacy, as cancer antigens are usually poorly immunogenic. Nanoparticle systems are promising tools as they act as carriers for antigens and can be surface-modified so that they specifically target antigen-presenting cells in lymph nodes. Bioinspired nanomaterials are ideal candidates thanks to their biocompatibility. Recently, melanin-based nanoparticles were reported to efficiently localize into draining lymphoid tissues and trigger immune responses against loaded antigens. In addition, by virtue of their photochemical properties, melanin-based nanoparticles can also play an immunomodulatory role to promote anti-cancer responses in the context of photothermal therapy. In this review, we discuss the above-mentioned properties of melanin, and summarize the promising results of the melanin-based cancer vaccines recently reported in preclinical models.

A Potent Cancer Vaccine Adjuvant System for Particleization of Short, Synthetic CD8+ T Cell Epitopes

Short major histocompatibility complex (MHC) class I (MHC-I)-restricted peptides contain the minimal biochemical information to induce antigen (Ag)-specific CD8⁺ cytotoxic T cell responses but are generally ineffective in doing so. To address this, we developed a cobalt-porphyrin (CoPoP) liposome vaccine adjuvant system that induces rapid particleization of conventional, short synthetic MHC-I epitopes, leading to strong cellular immune responses at nanogram dosing. Along with CoPoP (to induce particle formation of peptides), synthetic monophosphoryl lipid A (PHAD) and QS-21 immunostimulatory molecules were included in the liposome bilayer to generate the "CPQ" adjuvant system. In mice, immunization with a short MHC-I-restricted peptide, derived from glycoprotein 70 (gp70), admixed with CPQ safely generated functional, Ag-specific CD8⁺ T cells, resulting in the rejection of multiple tumor cell lines, with durable immunity. When cobalt was omitted, the otherwise identical peptide and adjuvant components did not result in peptide binding and were incapable of inducing immune responses, demonstrating the importance of stable particle formation. Immunization with the liposomal vaccine was well-tolerated and could control local and metastatic disease in a therapeutic setting. Mechanistic studies showed that particle-based peptides were better taken up by antigen-presenting cells, where they were putatively released within endosomes and phagosomes for display on MHC-I surfaces. On the basis of the potency of the approach, the platform was demonstrated as a tool for in vivo epitope screening of peptide microlibraries comprising a hundred peptides.

Engineering a Novel Bivalent Oral Vaccine against Enteric Fever

Enteric fever is a major global healthcare issue caused largely by Salmonella enterica serovars Typhi and Paratyphi A. The objective of this study was to develop a novel, bivalent oral vaccine capable of protecting against both serovars. Our approach centred on genetically engineering the attenuated S. Typhi ZH9 strain, which has an excellent safety record in clinical trials, to introduce two S. Paratyphi A immunogenic elements: flagellin H:a and lipopolysaccharide (LPS) O:2. We first replaced the native S. Typhi fliC gene encoding flagellin with the highly homologous fliC gene from S. Paratyphi A using Xer-cise technology. Next, we replaced the S. Typhi rfbE gene encoding tyvelose epimerase with a spacer sequence to enable the sustained expression of O:2 LPS and prevent its conversion to O:9 through tyvelose epimerase activity. The resulting new strain, ZH9PA, incorporated these two genetic changes and exhibited comparable growth kinetics to the parental ZH9 strain. A formulation containing both ZH9 and ZH9PA strains together constitutes a new bivalent vaccine candidate that targets both S. Typhi and S. Paratyphi A antigens to address a major global healthcare gap for enteric fever prophylaxis. This vaccine is now being tested in a Phase I clinical trial (NCT04349553).

MYC oncogene is associated with suppression of tumor immunity and targeting Myc induces tumor cell immunogenicity for therapeutic whole cell vaccination

Background

MYC oncogene is deregulated in 70% of all human cancers and is associated with multiple oncogenic functions including immunosuppression in the tumor microenvironment. The role of MYC in the immune microenvironment of neuroblastoma and melanoma is investigated and the effect of targeting Myc on immunogenicity of cancer cells is evaluated.

Methods

Immune cell infiltrates and immunogenic pathway signatures in the context of MYCN amplification were analyzed in human neuroblastoma tumors and in metastatic melanoma. Dose response and cell susceptibility to MYC inhibitors (I-BET726 and JQ1) were determined in mouse cell lines. The influence of downregulating Myc in tumor cells was characterized by immunogenic pathway signatures and functional assays. Myc-suppressed tumor cells were used as whole cell vaccines in preclinical neuroblastoma and melanoma models.

Results

Analysis of immune phenotype in human neuroblastoma and melanoma tumors revealed that MYCN or c-MYC amplified tumors respectively are associated with suppressed immune cell infiltrates and functional pathways. Targeting Myc in cancer cells with I-BET726 and JQ1 results in cell cycle arrest and induces cell immunogenicity. Combining vaccination of Myc-inhibited tumor cells with checkpoint inhibition induced robust antitumor immunity and resulted in therapeutic cancer vaccine therapy in mouse neuroblastoma tumors. Despite vigorous antitumor immunity in the mouse melanoma model, upregulation of immunosuppressive pathways enabled tumor escape.

Conclusions

This study demonstrates that the Myc oncogene is an appropriate target for inducing tumor cell immunogenicity and suggests that Myc-suppressed whole tumor cells combined with checkpoint therapy could be used for formulating a personalized therapeutic tumor vaccine.

Antitumor efficacy of a neoantigen cancer vaccine delivered by electroporation is influenced by microbiota composition

Cancer is a heterogeneous disease and its treatment remains unsatisfactory with inconstant therapeutic responses. This variability could be related, at least in part, to different and highly personalized gut microbiota compositions. Different studies have shown an impact of microbiota on antitumor therapy. It has been demonstrated that some gut bacteria influences the development and differentiation of immune cells, suggesting that different microbiota compositions could affect the efficacy of the antitumor vaccine. Emerging data suggest that recognition of neoantigens for the generation of neoantigen cancer vaccines (NCVs) could have a key role in the activity of clinical immunotherapies. However, it is still unknown whether there is a crosstalk between microbiota and NCV. This study aimed to understand the possible mechanisms of interaction between gut microbiota and NCV delivered by DNA-electroporation (DNA-EP). We found that decreased microbiota diversity induced by prolonged antibiotic (ATB) treatment is associated with higher intratumor specific immune responses and consequently to a better antitumor effect induced by NCV delivered by DNA-EP.

Suitability of databases in the Asia-Pacific for collaborative monitoring of vaccine safety

INTRODUCTION

Information regarding availability of electronic healthcare databases in the Asia-Pacific region is critical for planning vaccine safety assessments particularly, as COVID-19 vaccines are introduced. This study aimed to identify data sources in the region, potentially suitable for vaccine safety surveillance. This manuscript is endorsed by the International Society for Pharmacoepidemiology (ISPE).

METHODS

Nineteen countries targeted for database reporting were identified using published country lists and review articles. Surveillance capacity was assessed using two surveys: a 9-item introductory survey and a 51-item full survey. Survey questions related to database characteristics, covariate and health outcome variables, vaccine exposure characteristics, access and governance, and dataset linkage capability. Other questions collated research/regulatory applications of the data and local publications detailing database use for research.

RESULTS

Eleven databases containing vaccine-specific information were identified across 8 countries. Databases were largely national in coverage (8/11, 73%), encompassed all ages (9/11, 82%) with population size from 1.4 to 52 million persons. Vaccine exposure information varied particularly for standardized vaccine codes (5/11, 46%), brand (7/11, 64%) and manufacturer (5/11, 46%). Outcome data were integrated with vaccine data in 6 (55%) databases and available via linkage in 5 (46%) databases. Data approval processes varied, impacting on timeliness of data access.

CONCLUSIONS

Variation in vaccine data availability, complexities in data access including, governance and data release approval procedures, together with requirement for data linkage for outcome information, all contribute to the challenges in building a distributed network for vaccine safety assessment in the Asia-Pacific and globally. Common data models (CDMs) may help expedite vaccine safety research across the region.

Anti-SARS-CoV-2 vaccination strategy for pregnant women in Japan

The current COVID‐19 pandemic is a global concern. The recent introduction of vaccines has provided a reason for hope, but new problems, such as vaccine hesitancy, have arisen. One of the most important of these issues is the safety of vaccines for pregnant women. In this article, we collected worldwide indications for vaccination, including women who are pregnant or who wish to become pregnant, and reports of adverse reactions to COVID‐19 vaccination. The Japan Society of Obstetrics and Gynecology and the Japanese Society of Infectious Diseases in Obstetrics and Gynecology have published recommendations for the vaccination of pregnant women with a COVID‐19 vaccine. The guidelines are as follows: (1) pregnant women should not be excluded from vaccination; (2) informed consent should be obtained before vaccination; (3) healthcare workers and pregnant women with complications such as diabetes, hypertension, and obesity should be vaccinated preferentially; (4) vaccination should be avoided until 12 weeks of gestation during organogenesis; (5) spouse and family members should be vaccinated actively; and (6) nursing mothers are not particularly affected. This policy has been adopted in government guidelines. Additional efforts should be made to protect pregnant women from infection and severe illness with COVID‐19 by eliminating vaccine hesitancy.

Potent Neutralization Antibodies Induced by a Recombinant Trimeric Spike Protein Vaccine Candidate Containing PIKA Adjuvant for COVID-19

The structures of immunogens that elicit the most potent neutralization antibodies to prevent COVID-19 infection are still under investigation. In this study, we tested the efficacy of a recombinant trimeric Spike protein containing polyI:C (PIKA) adjuvant in mice immunized by a 0-7-14 day schedule. The results showed that a Spike protein-specific antibody was induced at Day 21 with titer of above 50,000 on average, as measured by direct binding. The neutralizing titer was above 1000 on average, as determined by a pseudo-virus using monoclonal antibodies (40592-MM57 and 40591-MM43) with IC50 at 1 μg/mL as standards. The protein/peptide array-identified receptor-binding domain (RBD) was considered as immunodominant. No linear epitopes were found in the RBD, although several linear epitopes were found in the C-terminal domain right after the RBD and heptad repeat regions. Our study supports the efficacy of a recombinant trimeric Spike protein vaccine candidate for COVID-19 that is safe and ready for storage and distribution in developing countries.

Measurement Invariance of the Drivers of COVID-19 Vaccination Acceptance Scale: Comparison between Taiwanese and Mainland Chinese-Speaking Populations

The impacts of novel coronavirus disease-2019 (COVID-19) on human life continue to be serious. To control the spread of COVID-19, the production of effective vaccines is likely to be one of the best solutions. However, vaccination hesitancy may decrease individuals' willingness to get vaccinated. The Drivers of COVID-19 Vaccination Acceptance Scale (DrVac-COVID19S) was recently developed to help healthcare professionals and researchers better understand vaccination acceptance. The present study examined whether DrVac-COVID19S is measurement invariant across different subgroups (Taiwanese vs. mainland Chinese university students; males vs. females; and health-related program majors vs. non-health-related program majors). Taiwanese (n = 761; mean age = 25.51 years; standard deviation (SD) = 6.42; 63.5% females) and mainland Chinese university students (n = 3145; mean age = 20.72 years; SD = 2.06; 50.2% females) were recruited using an online survey between 5 January and 21 February 2021. Factor structure and measurement invariance of the two DrVac-COVID19S scales (nine-item and 12-item) were tested using confirmatory factor analysis (CFA). The findings indicated that the DrVac-COVID19S had a four-factor structure and was measurement invariant across the subgroups. The DrVac-COVID19S's four-factor structure was supported by the CFA results is a practical and valid instrument to quickly capture university students' willingness to get COVID-19 vaccination. Moreover, the DrVac-COVID19S can be used to compare university students' underlying reasons to get COVID-19 vaccination among different subgroups.

Low Seroprevalence of Measles-Specific IgG in Children of Three Ethnic Groups from Mexico: Influence of Age, Sex, Malnutrition and Family Size

BACKGROUND

The reemergence of measles represents a public health problem. The aim of the study was to determine the seroprevalence of IgG antibodies against measles in children of three ethnic groups in southern Mexico and the nutritional status and demographic risk factors associated.

METHODS

A cross-sectional study in 416 school-age children, 207 belonging to the Tlapaneco ethnic group, 101 to the Mixteco group and 108 were considered Mestizo. Sociodemographic data were collected, an anthropometric evaluation of the children was performed and a fasting blood sample was obtained from each child for the measurement of measles IgG antibodies by Enzyme-Linked Immunosorbent Assay (ELISA).

RESULTS

From the total sample, 59% of the children were seropositive for IgG antibodies against measles; in contrast, 41% lacked IgG antibodies. Measles antibody seropositivity was higher in girls (64%). 90.5% of 6-year-old children had higher antibodies seroprevalence, compared to the children between 10 and 13 years old (45.5%). In the three ethnic groups, age was negatively correlated with the index standard ratio (ISR) of measles antibody levels and the families with ≥8 members showed less seropositivity. According to the antibodies levels, most of the positive cases remained around 1 Standard Deviation (SD) of the ISR values and no underweight children had antibody levels above 2 SD.

CONCLUSIONS

The Anti-Measles serological coverage is low in children of three ethnic groups from Southern Mexico and the age, sex, malnutrition and family size are associated factors. Therefore, it is important to strengthen immunization campaigns, principally in vulnerable groups.

Synthetic Analogs of Streptococcus pneumoniae Capsular Polysaccharides and Immunogenic Activities of Glycoconjugates

Streptococcus pneumoniae is a Gram-positive bacterium (pneumococcus) that causes severe diseases in adults and children. It was established that some capsular polysaccharides of the clinically significant serotypes of S. pneumoniae in the composition of commercial pneumococcal polysaccharide or conjugate vaccines exhibit low immunogenicity. The review considers production methods and structural features of the synthetic oligosaccharides from the problematic pneumococcal serotypes that are characterized with low immunogenicity due to destruction or detrimental modification occurring in the process of their preparation and purification. Bacterial serotypes that cause severe pneumococcal diseases as well as serotypes not included in the composition of the pneumococcal conjugate vaccines are also discussed. It is demonstrated that the synthetic oligosaccharides corresponding to protective glycotopes of the capsular polysaccharides of various pneumococcal serotypes are capable of inducing formation of the protective opsonizing antibodies and immunological memory. Optimal constructs of oligosaccharides from the epidemiologically significant pneumococcal serotypes are presented that can be used for designing synthetic pneumococcal vaccines, as well as test systems for diagnosis of S. pneumoniae infections and monitoring of vaccination efficiency .

The Impact of a Single Educational Lecture on the Vaccine Confidence among Pregnant Women and Young Mothers

Background: We investigated the impact of a single unstructured educational lecture about vaccinations on the vaccine confidence in volunteer participants. Methods: We conducted a survey-based study during a series of open meetings related to pregnancy and parenting. Before and after the pediatrician’s lecture related to vaccinations, listeners completed the visual analogue scales (VAS, 0–15 cm), evaluating (1) self-declared knowledge on vaccinations and (2) how they perceive the safety and efficacy of this preventive method. Results: In total, 484 women aged 30 ± 4 years participated in the lecture (pregnant = 68%; ≥1 children = 56%). Participants declared to have more comprehensive knowledge on preventive vaccinations and perceived vaccines to be safer and more useful (the role for the immunity) after vs. before the lecture (median VAS: 10.4 vs. 7.2, 10.8 vs. 8.7, and 11.0 vs. 10.4 cm, all p < 0.001). Importantly, the prevalence of vaccine-related adverse events was also assessed as being higher after the lecture (median VAS: 9.9 vs. 8.0 cm, p < 0.001). The increase in self-declared knowledge on vaccinations and perceived need for vaccinations (delta VAS—VAS after minus before the lecture, expressed as % of baseline) was lower among participants who rated the lecture less vs. more useful. Importantly, both participants who liked vs. did not like the lecture comparably rated vaccines safer after vs. before the lecture (delta VAS (median, interquartile range): 16% (0–39%) vs. 18% (2–42%), p = 0.39). Conclusions: An educational lecture on vaccinations positively impacts vaccine confidence in young adult women. Irrespective of the subjective rating of the lecture, all listeners perceived vaccinations to be safer after vs. before the speech.

Perception of COVID-19 Vaccination Amongst Physicians in Colombia

Introduction: The SARS-CoV-2/COVID-19 pandemic has triggered the need to develop rapidly effective and safe vaccines to prevent infection, particularly in those at-risk populations such as medical personnel. This study's objective was to assess the perception of COVID-19 vaccination amongst Colombian physicians featuring two different scenarios of COVID-19 vaccination. Methods: A cross-sectional analytical study was carried out through an online survey directed at medical staff in several cities in Colombia. The percentage of physicians who have a positive perception to be vaccinated and the associated factors that determine that decision were determined. A binomial regression analysis adjusted for age and sex was carried out, taking as a dependent variable the acceptance of free vaccination with an effectiveness of 60 and 80%. The most significant factors were determined in the non-acceptance of vaccination. Results: Between 77.0% and 90.7% of physicians in Colombia accept COVID-19 vaccination, according to the scenario evaluated where the vaccine's effectiveness was 60 or 80%, respectively. Medical specialty, having never paid for a vaccine, recommending the administration of the vaccine to their parents or people over 70 years, and dispensing the vaccine to their children, were the factors to consider to be vaccinated for free with an effectiveness of 60% and 80%. Conclusions: There is a high perception of the intention to vaccinate physicians in Colombia against COVID-19, and this is very similar to that of the general population.