Immunization in special populations

Pharmacovigilance in Vaccines: Importance, Main Aspects, Perspectives, and Challenges-A Narrative Review

Pharmacovigilance plays a central role in safeguarding public health by continuously monitoring the safety of vaccines, being critical in a climate of vaccine hesitancy, where public trust is paramount. Pharmacovigilance strategies employed to gather information on adverse events following immunization (AEFIs) include pre-registration data, media reports, clinical trials, and societal reporting. Early detection of AEFIs during clinical trials is crucial for thorough safety analysis and preventing serious reactions once vaccines are deployed. This review highlights the importance of societal reporting, encompassing contributions from community members, healthcare workers, and pharmaceutical companies. Technological advancements such as quick response (QR) codes can facilitate prompt AEFI reporting. While vaccines are demonstrably safe, the possibility of adverse events necessitates continuous post-marketing surveillance. However, underreporting remains a challenge, underscoring the critical role of public engagement in pharmacovigilance. This narrative review comprehensively examines and synthesizes key aspects of virus vaccine pharmacovigilance, with special considerations for specific population groups. We explore applicable legislation, the spectrum of AEFIs associated with major vaccines, and the unique challenges and perspectives surrounding pharmacovigilance in this domain.

Immunization of laboratory animal workers: occupational health and safety aspects

Occupational immunization is an integral part of institutional occupational safety and health (OSH) programs. Laboratory animal workers (LAWs) are personnel working with various small and large vertebrate animals. LAWs are at the risk of contracting a myriad of zoonotic infections as they are occupationally exposed to animals and their biological products. Immunizing employees against such zoonotic pathogens is the best way to prevent disease transmission. This review provides information on various zoonotic diseases, vaccines available to protect against such infections, and vaccination schedules. Certain sections of institutional occupational immunization programs such as risk evaluation, immunizing special categories of personnel and exemption from immunization among others are also described. Additionally, the authors have discussed various probable modes of impact through which occupational immunization of laboratory animal workers fulfills different United Nations Sustainable Development Goals.

Rubella antibodies in vertically and horizontally HIV-infected young adults vaccinated early in life and response to a booster dose in those with seronegative results

BACKGROUND

Very limited data are available on the persistence of rubella antibodies in vertically HIV-infected individuals who were vaccinated early in life.

METHODS

Prospective, cohort study on 4 groups of patients: 96 vertically HIV-1-infected individuals (v-HIV), 69 horizontally HIV-1-infected individuals (h-HIV), 93 healthy controls previously vaccinated for rubella (vac-CON) and 20 healthy controls with history of rubella disease (dis-CON). A blood sample was collected and rubella antibodies were analyzed by ELISA. Rubella antibodies above 10 IU/mL were considered protective. Individuals with seronegative results were offered an extra MMR vaccine dose and were tested at least 30 days afterwards.

RESULTS

Time since previous rubella vaccination was similar in v-HIV, h-HIV and vac-CON (16, 11 and 11 years; p = 0.428). v-HIV and h-HIV were also comparable regarding median CD4 T cells (613 and 614 cells/mm³; p = 0.599) and percentage on ART (93.8% and 98.6%; p = 0.135) at study entry. v-HIV had less individuals on virological suppression (63.5%) compared to 85.5% in h-HIV (p < 0.001). Rubella seropositivity and antibodies were significantly lower in v-HIV compared to h-HIV (32.3% vs 65.5%, 4.3 IU/mL vs 21.1 IU/mL; p < 0.001). Time interval between the last rubella vaccine dose and study entry was associated with an increase of rubella seronegativity, with a 7% higher chance of seronegativity for each one-year increase. After an extra MMR dose, 40 out of 48 (83.3%) seronegative individuals responded, with no significant difference among groups considering rubella seropositivity and antibody levels.

CONCLUSION

As vertically HIV-infected individuals reach adolescence and adulthood, assessment of vaccine antibodies can identify those who might benefit from an extra vaccine dose.

The combination of artificial intelligence and systems biology for intelligent vaccine design

INTRODUCTION

A new body of evidence depicts the applications of artificial intelligence and systems biology in vaccine design and development. The combination of both approaches shall revolutionize healthcare, accelerating clinical trial processes and reducing the costs and time involved in drug research and development.

AREAS COVERED

This review explores the basics of artificial intelligence and systems biology approaches in the vaccine development pipeline. The topics include a detailed description of epitope prediction tools for designing epitope-based vaccines and agent-based models for immune system response prediction, along with a focus on their potentiality to facilitate clinical trial phases.

EXPERT OPINION

Artificial intelligence and systems biology offer the opportunity to avoid the inefficiencies and failures that arise in the classical vaccine development pipeline. One promising solution is the combination of both methodologies in a multiscale perspective through an accurate pipeline. We are entering an 'in silico era' in which scientific partnerships, including a more and more increasing creation of an 'ecosystem' of collaboration and multidisciplinary approach, are relevant for addressing the long and risky road of vaccine discovery and development. In this context, regulatory guidance should be developed to qualify the in silico trials as evidence for intelligent vaccine development.

OMIC Technologies and Vaccine Development: From the Identification of Vulnerable Individuals to the Formulation of Invulnerable Vaccines

Routine vaccination is among the most effective clinical interventions to prevent diseases as it is estimated to save over 3 million lives every year. However, the full potential of global immunization programs is not realised because population coverage is still suboptimal. This is also due to the inadequate immune response and paucity of informative correlates of protection upon immunization of vulnerable individuals such as newborns, preterm infants, pregnant women, and elderly individuals as well as those patients affected by chronic and immune compromising medical conditions. In addition, these groups are undervaccinated for a number of reasons, including lack of awareness of vaccine-preventable diseases and uncertainty or misconceptions about the safety and efficacy of vaccination by parents and healthcare providers. The presence of these nonresponders/undervaccinated individuals represents a major health and economic burden to society, which will become particularly difficult to address in settings with limited public resources. This review describes innovative and experimental approaches that can help identify specific genomic profiles defining nonresponder individuals for whom specific interventions might be needed. We will provide examples that show how such information can be useful to identify novel biomarkers of safety and immunogenicity for future vaccine trials. Finally, we will discuss how system biology “OMICs” data can be used to design bioinformatic tools to predict the vaccination outcome providing genetic and molecular “signatures” of protective immune response. This strategy may soon enable identification of signatures highly predictive of vaccine safety, immunogenicity, and efficacy/protection thereby informing personalized vaccine interventions in vulnerable populations.

Completeness and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and polio vaccines in young children with chronic health conditions: A systematic review

OBJECTIVE

To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines ininfants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6 months of life.

METHODS

Using a standardized search strategy developed by a medical librarian, records were extracted from MEDLINE, Embase, Database of Abstracts of Reviews of Effects, and CINAHL up to May 8, 2018.

RESULTS

Out of the 1997 records that were screened, we identified 21 studies that met inclusion criteria. Eleven studies assessed vaccine coverage and/or timeliness in preterm infants, 6 in low birth weight infants, and 7 in children with chronic health conditions. Estimates of coverage in these populations were highly variable, ranging from 40% to 100% across the vaccines and population groups.

CONCLUSIONS

There is a lack of studies reporting coverage and timeliness of routine immunizations in special populations of children.

POLICY IMPLICATIONS

Our review suggests a need for improved surveillance of immunization status in special populations of infants, as wellas aneed for standardization of reporting practices.

Effect of HIV exposure and timing of antiretroviral therapy initiation on immune memory responses to diphtheria, tetanus, whole cell pertussis and hepatitis B vaccines

OBJECTIVES

We evaluated memory responses and antibody persistence to diphtheria-toxoid, tetanus-toxoid, whole-cell-pertussis (DTwP), and Hepatitis-B vaccines in HIV-unexposed, HIV-exposed-uninfected and HIV-infected children previously randomized to initiate time-limited ART at 6-10 weeks (ART-Immed) or when clinically/immunologically indicated (ART-Def).

METHODS

All children received DTwP booster at 15-18 months. Antibodies were measured for pertussis-toxoid, filamentous haemagglutinin (FHA), diphtheria-toxoid, tetanus-toxoid, and hepatitis-B prior to booster, 1-2 weeks post-booster and at 24 months of age.

RESULTS

Pre-booster antibody GMC were lower in HIV-infected groups than HIV-unexposed children for all epitopes. Post-booster and at 24 months of age, the ART-Def group had lower GMCs and antibody proportion ≥0.1 IU/ml for tetanus-toxoid and diphtheria-toxoid compared to HIV-unexposed children. At 24 months of age, the ART-Immed group had higher GMCs, and more likely to maintain antibody titres ≥1.0 IU/ml to tetanus-toxoid and diphtheria-toxoid compared to HIV-unexposed children. Compared to HIV-unexposed children, at 15 and 24 months of age, persistence of antibody to HBsAg of ≥10 mIU/ml was similar in the ART-Immed group but lower among the ART-Def group. Antibody kinetics indicated more robust memory responses in HIV-exposed-uninfected than HIV-unexposed children to diphtheria-toxoid and wP.

CONCLUSION

HIV-infected children not on ART at primary vaccination had poorer memory responses, whereas HIV-exposed-uninfected children mounted robust memory responses.

Seroprevalence of antibodies against the three serotypes of poliovirus and IPV vaccine response in adult solid organ transplant candidates

OBJECTIVES

To assess the prevalence of protective antibody titers to polioviruses in adults candidates for solid organ transplant (SOT), and to assess the immunogenic response to inactivated polio vaccine in this population.

METHODS

The study included SOT candidates referred to Immunization Reference Centre of Evandro Chagas National Institute of Infectious Diseases from March 2013 to January 2016. It was conducted in 2 phases. The first one, a cross-sectional seroprevalence study, followed by an uncontrolled analysis of vaccine response among patients without protective antibody titers at baseline. Antibody titers to poliomyelitis were determined by microneutralization assay.

RESULTS

Among 206 SOT candidates included, 156 (76%) had protective antibody titers to all poliovirus serotypes (95% CI: 70-81%). Proven history of oral vaccination in childhood was not associated with higher seroprevalence of protective antibody. In 97% of individuals without protective antibody titers at baseline, there was adequate vaccine response with one dose of inactivated polio vaccine.

CONCLUSIONS

A relevant proportion of adult candidates for SOT does not have protective titers of antibodies to one or more poliovirus serotype. One dose of inactivated vaccine elicited protective antibody titers in 97% of these subjects and should be routinely prescribed prior to SOT.

Vaccination of special populations: Protecting the vulnerable

One of the strategic objectives of the 2011-2020 Global Vaccine Action Plan is for the benefits of immunisation to be equitably extended to all people. This approach encompasses special groups at increased risk of vaccine-preventable diseases, such as preterm infants and pregnant women, as well as those with chronic and immune-compromising medical conditions or at increased risk of disease due to immunosenescence. Despite demonstrations of effectiveness and safety, vaccine uptake in these special groups is frequently lower than expected, even in developed countries with vaccination strategies in place. For example, uptake of the influenza vaccine in pregnancy rarely exceeds 50% in developed countries and, although data are scarce, it appears that only half of preterm infants are up-to-date with routine paediatric vaccinations. Many people with chronic medical conditions or who are immunocompromised due to disease or aging are also under-vaccinated. In the US, coverage among people aged 65years or older was 67% for the influenza vaccine in the 2014-2015 season and 55-60% for tetanus and pneumococcal vaccines in 2013, while the coverage rate for herpes zoster vaccination among those aged 60years or older was only 24%. In most other countries, rates are far lower. Reasons for under-vaccination of special groups include fear of adverse outcomes or illness caused by the vaccine, the inconvenience (and in some settings, cost) of vaccination and lack of awareness of the need for vaccination or national recommendations. There is also evidence that healthcare providers' attitudes towards vaccination are among the most important influences on the decision to vaccinate. It is clear that physicians' adherence to recommendations needs to be improved, particularly where patients receive care from multiple subspecialists and receive little or no care from primary care providers.

Evaluation of Reference Centers for Special Immunobiologicals implementation

OBJECTIVE

To describe the Reference Centers for Special Immunobiologicals and evaluate their implementation considering formal regulations.

METHODS

We conducted a program evaluation, of evaluative research type. From August 2011 to January 2012, a questionnaire was applied to the 42 Reference Centers for Special Immunobiologicals existing in the Country, approaching the structure, human resources, and developed activities dimensions. We conducted a descriptive analysis of data and used a clustering for binary data with the squared Euclidean distance, by the farthest neighbor method, to aggregate services with similar features.

RESULTS

We observed great diversity among the services in the three dimensions. The clustering resulted in five service profiles, named according to their characteristics. 1) Best structure: 12 Reference Centers for Special Immunobiologicals with the highest proportion of services with the minimum of rooms recommended, purpose-built vaccine refrigerators, preventive maintenance of the cold chain, and oxygen source. 2) Immunobiologicals distributor: six Reference Centers for Special Immunobiologicals that distributed more than applied immunogens; no doctor present for more than half of the working hours and no purpose-built vaccine refrigerators . 3) Incipient implementation: five Reference Centers for Special Immunobiologicals with inadequate structure, such as absence of purpose-built vaccine refrigerators, preventive maintenance of the cold chain and oxygen source; none had computer. 4) Vaccination rooms: 13 Reference Centers for Special Immunobiologicals, everyone did routine immunization, most participated in vaccination campaigns. 5) Teaching and research: six services, all inserted into teaching hospitals, developed researches and received trainees; most had doctors in more than half of the working hours.

CONCLUSIONS

The evaluation of the Reference Centers for Special Immunobiologicals implementation was based on the profiles found and considered the official regulations: services categorized as "better structure" and "teaching and research" were considered implemented; "immunobiologicals distributor" and "vaccination room" services, partially implemented, and the ones with the "incipient implementation" profile, not implemented. The results of this evaluation can contribute to the reformulation of the services, considering the current context.

OBJETIVO

Descrever os Centros de Referência para Imunobiológicos Especiais e avaliar sua implantação considerando as regulamentações formais.

MÉTODOS

Foi realizada uma avaliação de programa, tipo pesquisa avaliativa. De agosto de 2011 a janeiro de 2012, foi aplicado questionário aos responsáveis pelos 42 Centros de Referência para Imunobiológicos Especiais existentes no País, abordando as dimensões estrutura, recursos humanos e atividades desenvolvidas. Foi feita análise descritiva dos dados e utilizado agrupamento para dados binários com uso da distância euclidiana quadrática, pelo método do vizinho mais distante, para agregar serviços com características semelhantes.

RESULTADOS

Observou-se grande diversidade entre os serviços nas três dimensões. O agrupamento resultou em cinco perfis de serviços, denominados de acordo com suas características. 1) Melhor estrutura: 12 Centros de Referência para Imunobiológicos Especiais com a maior proporção de serviços com o mínimo de salas preconizado, câmaras de vacinas, manutenção preventiva da rede de frio e fonte de oxigênio. 2) Dispensador de imunobiológicos: seis Centros de Referência para Imunobiológicos Especiais que mais dispensavam do que aplicavam imunógenos; sem médico presente por mais da metade do expediente do serviço e sem câmara de vacinas. 3) Implantação incipiente: cinco Centros de Referência para Imunobiológicos Especiais com estrutura inadequada, como ausência de câmaras de vacinas, de manutenção preventiva da rede de frio e de fonte de oxigênio; nenhum possuía computador. 4) Sala de vacinas: 13 Centros de Referência para Imunobiológicos Especiais, todos faziam imunização de rotina, a maioria participava de campanhas de vacinação. 5) Ensino e pesquisa: seis serviços, todos inseridos em hospitais de ensino, desenvolviam pesquisas e recebiam estagiários; a maioria possuía médicos em mais da metade do expediente.

CONCLUSÕES

A avaliação de implantação dos Centros de Referência para Imunobiológicos Especiais baseou-se nos perfis encontrados e considerou as regulamentações oficiais: os serviços categorizados como "melhor estrutura" e "ensino e pesquisa" foram considerados implantados; os serviços "dispensador de imunobiológicos" e "sala de vacinas", parcialmente implantados e os do perfil "implantação incipiente", não implantados. Os resultados dessa avaliação podem contribuir para a reformulação dos serviços, considerando o contexto atual.

Hepatitis B vaccination for reducing morbidity and mortality in persons with HIV infection

BACKGROUND

Hepatitis B vaccine has been recommended for use in people living with HIV (PLHIV) mostly because of the similarities in routes of infection and their prevalence in the same geographic areas. PLHIV may not develop sero-protection after receiving standard hepatitis B vaccine due to their compromised immune status.

OBJECTIVES

To evaluate the efficacy of hepatitis B virus vaccine in PLHIV compared to placebo or no vaccine.

SEARCH METHODS

We searched 6 English language databases in July 2012, and updated the search in June 2013 and August 2014. We searched the grey literature, conference proceedings, specialised web sites, and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials of hepatitis B vaccine compared to placebo or no vaccine, evaluating relevant outcomes of efficacy and safety.

DATA COLLECTION AND ANALYSIS

Two review authors independently sought and extracted data on study design, participants, hepatitis B infection, hepatitis B related morbidity and mortality, anti-HBs immunogenicity and adverse effects related to vaccines from published articles or through correspondence with authors. Data were analysed qualitatively.

MAIN RESULTS

One double-blind randomised controlled trial with 26 participants who were on antiretroviral therapy (ART), comparing hepatitis B vaccine to placebo conducted in Spain met our eligibility criteria and was included in this review. The study ran for three years and participants were followed up on a monthly basis. The study reported adequate humoral response to vaccine at 12 months and no local or systematic side effects in both intervention and control groups. This humoral response was lost when the participants stopped taking ART. The sample size of the study was small and the study was conducted in a high income setting unlike the areas of highest burden of hepatitis B and HIV co-infections.

AUTHORS' CONCLUSIONS

The evidence from this study is insufficient to support any recommendations regarding the use of hepatitis B vaccine in PLHIV. Neither does this evidence demonstrate that hepatitis B vaccine is unsafe in PLHIV. Further randomised controlled trials in high prevalence areas are required to generate evidence on the long term efficacy and safety of hepatitis B vaccine in PLHIV with and without ART. Different regimens and routes of administration should also be explored.

Targeting antigens to CD180 rapidly induces antigen-specific IgG, affinity maturation, and immunological memory

Targeting antigen to B cells and dendritic cells via direct conjugation to anti-CD180 antibody promotes robust antigen-specific antibody responses in the absence of adjuvant.

Antigen (Ag) targeting is an efficient way to induce immune responses. Ag is usually coupled to an antibody (Ab) specific for a receptor expressed on dendritic cells (DCs), and then the Ag–anti-receptor is inoculated with an adjuvant. Here we report that targeting Ag to a receptor expressed on both B cells and DCs, the TLR orphan receptor CD180, in the absence of adjuvant rapidly induced IgG responses that were stronger than those induced by Ag in alum. Ag conjugated to anti-CD180 (Ag-αCD180) induced affinity maturation and Ab responses that were partially T cell independent, as Ag-specific IgGs were generated in CD40- and T cell–deficient mice. After preimmunization with Ag-αCD180 and boosting with soluble Ag, both WT and CD40 knockout (KO) mice rapidly produced Ag-specific IgG-forming cells, demonstrating that Ag–anti-CD180 induces immunological memory. The potent adjuvant effect of Ag-αCD180 required Ag to be coupled to anti-CD180 and the responsive B cells to express both CD180 and an Ag-specific B cell receptor. Surprisingly, CD180 Ag targeting also induced IgG Abs in BAFF-R KO mice lacking mature B cells and in mice deficient in interferon signaling. Targeting Ag to CD180 may be useful for therapeutic vaccination and for vaccinating the immune compromised.