Vaccine Challenge Research Articles

PRRSV-Vaccinated, Seronegative Sows and Maternally Derived Antibodies (II): Impact on PRRSV-1 Vaccine Effectiveness and Challenge Outcomes in Piglets.

Vaccination against the Porcine Reproductive and Respiratory Syndrome virus (PRRSV) is widely practiced in both sows and piglets. However, it has been shown that multivaccinated sows sometimes lack a detectable antibody response, testing seronegative in ELISA (non-responders). Moreover, PRRSV-vaccinated piglets can remain seronegative as well, which is mainly attributed to the interference of maternally derived antibodies (MDAs). The current study investigated the impact of the sow's immune status on the PRRSV vaccine effectiveness in the progeny. The experimental trial included forty-eight piglets (n = 48) originating from a commercial Belgian breeding herd, with twenty-four piglets born from PRRSV vaccinated responder sows (E+ piglets) and twenty-four piglets born from PRRSV vaccinated non-responder sows (E- piglets). Eight piglets in each group were either non-vaccinated (NoVac piglets; n = 8), intramuscularly vaccinated (IM piglets; n = 8), or intradermally vaccinated (ID piglets; n = 8), with the same PRRSV-1 vaccine as used in the sow population. Vaccination was performed at weaning at three weeks of age, and all study piglets were challenged with a high dose of the PRRSV-1 07V063 strain at 6 weeks of age. A clear interference of MDAs was observed in the E+ piglets: 66.7% of the vaccinated E+ piglets lacked an antibody response at 3 weeks post-vaccination (non-responders). Consequently, post-challenge, only the responding E+ piglets had a significantly reduced serum viremia compared to the E+ NoVac piglets. The observed viremia in the non-responding E+ piglets was similar to the viremia of the E+ NoVac piglets. In the vaccinated E- piglets, a lack of antibody response at 3 weeks post-vaccination was observed in 18.8% of the piglets. Interestingly, despite the lack of a vaccine antibody response, the non-responding E- piglets had a significantly reduced serum viremia compared to the NoVac E- piglets. In contrast, the viremia of the responding E- piglets was only numerically reduced compared to the NoVac E- piglets. Finally, some clear differences were observed in both the kinetics of infection and the immune responses post-challenge between the E+ and E- piglets. The results of this study confirm the consequences of the MDA interference on the induced partial protection of PRRSV vaccination in experimentally challenged piglets. More research is warranted to understand the immunological mechanisms behind MDA interference in PRRSV vaccination and to explain the observed differences between E+ and E- piglets.

Covid-19 vaccination: a mixed methods analysis of health system resilience in Latin America

BackgroundThis paper discusses the stages of health system resilience (HSR) and the factors underlying differences in HSR during the covid-19 pandemic, especially the vaccination challenge. We studied the relationship between vaccination strategies and macro-context backgrounds in 21 Latin American countries. Our objective was to capture the impact of those aspects in the SR and identify potential improvements for future crises and for vaccination programs in general.MethodsThe study uses mixed-methods research to provide insights into how the countries’ backgrounds and vaccination strategies impact the HSR. Particularly, we used explanatory sequential mixed methods, which entails a quantitative-qualitative two-phase sequence. The quantitative phase was conducted using cluster and variance analysis, in which the HSR was measured using as a proxy the covid-19 vaccination outcomes in three cut-offs of reaching 25%, 50%, and 75% of population coverage. This approach allows us to discriminate covid-19 vaccination progress by stages and contrast it to the qualitative stage, in which we performed a country-case analysis of the background conditions and the changes in vaccination strategies that occurred during the corresponding dates.ResultsThe paper provides a rich comparative case analysis of countries, classifying them by early, prompt, and delayed performers. The results show that differences in vaccination performance are due to flexibility in adapting strategies, cooperation, and the ability to design multilevel solutions that consider the needs of various actors in the health ecosystem. These differences vary depending on the vaccination stage, which suggests the importance of acknowledging learning, diffusion, and feedback processes at the regional level.ConclusionsWe identified the importance of societal well-being as an ideal country antecedent for high and sustained levels of performance in covid-19 vaccination. Whereas in other countries where the set-up and beginning phases were rough, the value of the operational decisions and the learning on the move regarding their own and their peers’ trajectories were crucial and were reflected in performance improvement. A contribution of this study is that the above-mentioned analysis was done using vaccination coverage cut-off points that allow a performance view that takes into consideration the stages of the vaccination progress and the learning process that goes with it. As well as framing this into the HSR shock cycles that allow to differentiate the stages of resilience on which countries must act.

IL-27 alters inflammatory cytokine expression and limits protective immunity against Mycobacterium tuberculosis in a neonatal BCG vaccination model.

Efforts to control tuberculosis (TB), caused by the pathogen Mycobacterium tuberculosis (Mtb), have been hampered by the immense variability in protection from BCG vaccination. While BCG protects young children from some forms of TB disease, long-term protection against pulmonary disease is more limited, suggesting a poor memory response. New vaccines or vaccination strategies are required to have a realistic chance of eliminating TB disease. In TB endemic areas, routine immunization occurs during the neonatal period and as such, we hypothesized that inadequate protective immunity elicited by BCG vaccination could be the result of the unique early-life immune landscape. Interleukin (IL)-27 is a heterodimeric cytokine with immune suppressive activity that is elevated in the neonatal period. We investigated the impact of IL-27 on regulation of immune responses during neonatal BCG vaccination and protection against Mtb. Here, we used a novel model of neonatal vaccination and adult aerosol challenge that models the human timeline of vaccine delivery and disease transmission. Overall, we observed improved control of Mtb in mice unresponsive to IL-27 (IL-27Rα-/-) that was consistent with altered expression patterns of IFN-γ and IL-17 in the lungs. The balance of these cytokines with TNF-α expression may be key to effective bacterial clearance. Our findings suggest the importance of evaluating new vaccines and approaches to combat TB in the neonatal population most likely to receive them as part of global vaccination campaigns. They further indicate that temporal strategies to antagonize IL-27 during early life vaccination may improve protection.

Exploring Vaccination Challenges among Syrian Refugees in Jordan: Insights from Camps and Communities, and Perceived Parental Barriers to Childhood Vaccination Uptake.

To identify and understand the multifaceted barriers faced by Syrian refugees when seeking vaccination services for their children. A survey questionnaire was administered through structured interviews to a sample of Syrian refugees residing inside the Al-Zaatari camp and in various urban areas across Jordanian communities. This process utilized a multi-stage sampling approach, beginning with a random selection from clusters or strata, and then employing convenience sampling within each to select participants. The survey covered demographics, barriers to vaccination, and vaccine hesitancy. A total of 332 participants completed the survey with a mean age of 32.7 ± 10 years ranging from 18 to 67. More than half of the sample (59%) had an education of 11th grade or less. Sociodemographic disparities regarding barrier perception were evident among participants. Middle-aged adults (older than 32), males, and those with a monthly income less than USD 200 had scored significantly higher on barrier perceptions across all categories (p < 0.05). In-camp residents were less likely to face vaccination barriers compared to those living outside the camps (p < 0.001). Psychological antecedents of vaccine assessments showed that younger individuals had significantly higher scores in complacency, calculation, and constraints (p < 0.05). Participants with lower income had lower constraints and calculation scores (p < 0.05). In-camp residents had significantly higher scores in complacency, constraints, and calculation constructs compared outside camps counterparts (p < 0.05). Participants with no formal education had higher scores in complacency and constraints, and those with less than a 12th-grade education and higher education degrees scored significantly higher on the collective responsibility construct (p < 0.05). Efforts to promote vaccination among refugees should consider the specific challenges faced by this population, including financial barriers, healthcare access inequalities, and the impact of living arrangements. Public health strategies should address not only individual and psychological factors but also the physical and logistical challenges in obtaining vaccines.

Unraveling the tapestry: Immune imprinting amidst a spectrum of challenges for modRNA Covid-19 vaccines

Unraveling the tapestry: Immune imprinting amidst a spectrum of challenges for modRNA Covid-19 vaccines

The current state of pertussis vaccination in pregnancy around the world, with recommendations for improved care: Consensus statements from the Global Pertussis Initiative.

Bordetella pertussis, which causes a respiratory disease known as pertussis ("whooping cough") remains an important global challenge, with the incidence in pertussis cases increasing in recent years. Newborns and infants are at increased risk for severe morbidity and mortality from this bacterium. Vaccination in pregnancy has become an important strategy to both passively transfer immunity as well as prevent infection in pregnant persons, who are a major source of newborn infection, thus attempting to decrease the impact of this serious disease. It is considered safe for the pregnant person, the developing fetus, and the infant, and during the first 3 months of life it has been shown to be highly effective in preventing pertussis. There are a variety of strategies, recommendations, and adherence rates associated with pertussis vaccination in pregnancy around the world. We summarize the 2021 Global Pertussis Initiative Annual Meeting that reviewed the current global status of pertussis vaccination in pregnancy and remaining medical and scientific questions, with a focus on vaccination challenges and strategies for obstetric and gynecologic healthcare providers.

Lessons Learned From Adolescent COVID-19 Vaccine Administration in Medically Underserved Communities.

In May 2021, the Health Resources and Services Administration Health Center COVID-19 Vaccine Program (HCCVP) began supporting the national adolescent vaccination rollout for a safe return to in-person learning for children and adolescents from medically underserved communities. To understand the initial implementation of adolescent vaccinations, we estimated the number of vaccines administered through the HCCVP at the national and state level to adolescents aged 12-17 years, and we examined challenges and solutions in vaccine deployment. We analyzed data on vaccine administration, challenges, and solutions from the Health Center COVID-19 Survey during May 14-August 27, 2021, and we analyzed data on patients served from the 2019 Uniform Data System. National adolescent COVID-19 vaccination and population data came from CDC's COVID Data Tracker and the US Census Bureau's 2019 Current Population Survey. HCCVP health centers administered >485 000 COVID-19 vaccine doses to adolescents during the study period, with variations across states. Health centers in 13 states and territories (Arizona, California, Colorado, Connecticut, Delaware, Maine, Massachusetts, Missouri, Nebraska, Nevada, Oregon, Virginia, and Puerto Rico) vaccinated more adolescents than their share of prepandemic adolescent patients. The most frequently reported challenges in vaccine administration were vaccine confidence and staffing availability. This assessment of the initial months of COVID-19 vaccine administration among adolescent health center patients suggests rapid response by health centers in several states, reaching beyond their adolescent patient population to support state-level pandemic response. Future research could examine processes to optimize strategic activation of health centers in public health emergency responses.

Minimalist Nanovaccine with Optimized Amphiphilic Copolymers for Cancer Immunotherapy.

Cancer vaccines with the ability to elicit tumor-specific immune responses have attracted significant interest in cancer immunotherapy. A key challenge for effective cancer vaccines is the spatiotemporal codelivery of antigens and adjuvants. Herein, we synthesized a copolymer library containing nine poly(ethylene glycol) methyl ether methacrylate-co-butyl methacrylate-co-2-(azepan-1-yl)ethyl methacrylate (PEGMA-co-BMA-co-C7AMA) graft copolymers with designed proportions of different components to regulate their properties. Among these polymers, C-25, with a C7AMA:BMA ratio at 1.5:1 and PEG wt % of 25%, was screened as the most effective nanovaccine carrier with enhanced ability to induce mouse bone marrow-derived dendritic cell (BMDC) maturation. Additionally, RNA-sequencing (RNA-Seq) analysis revealed that C-25 could activate dendritic cells (DCs) through multisignaling pathways to trigger potent immune effects. Then, the screened C-25 was used to encapsulate the model peptide antigen, OVA257-280, to form nanovaccine C-25/OVA257-280. It was found that the C-25/OVA257-280 nanovaccine could effectively facilitate DC maturation and antigen cross-presentation without any other additional adjuvant and exhibited excellent prophylactic efficacy in the B16F10-OVA tumor model. Moreover, in combination with antiprogrammed cell death protein-ligand 1 (anti-PD-L1), the C-25/OVA257-280 nanovaccine could significantly delay the growth of pre-existing tumors. Therefore, this work developed a minimalist nanovaccine with a simple formulation and high efficiency in activating tumor-specific immune responses, showing great potential for further application in cancer immunotherapy.

Effectiveness and impact of Covid-19 response and vaccination challenges in Namibia: a systematic review

Introduction: Namibia, like several countries globally, is currently grappling with the severe repercussions of the Covid-19 pandemic on its economy, psycho-social connections, and overall public well-being. These nations have implemented multiple steps to mitigate the transmission of the SARS-CoV-2 virus, which causes severe acute respiratory syndrome. Namibia implemented measures to mitigate the transmission and mortality caused by the virus. The nature and execution tactics of Public Health regulations significantly affect the prevention of the spread and reduction of mortality caused by the virus. Objective: This article provides a comprehensive analysis on the efficacy and consequences of Public Health measures implemented by the Health Authority to mitigate the spread of covid-19 among the general population. Method: The review employed the elements of the PRISMA technique to synthesize data on a specific area of focus. We utilized several resources, including Scopus, ScienceDirect, Google Scholar, World Health Organization, and the Ministry of Health and Social Services of Namibia (MoHSS), to gather comprehensive information on covid-19. Observation: The country experienced a consistent rise in Covid-19 cases, with an average daily increase of eleven (11) infections, until June 2021. The highest rate was associated with densely inhabited areas of Erongo and Khomas. The control methods implemented for infection prevention and vaccination campaign were largely ineffectual due to widespread misunderstanding. Conclusion: To effectively limit the spread of the virus and save lives, it is necessary to adopt a new approach that involves improved communication and engagement with the local population.

A comprehensive narrative review of challenges and facilitators in the implementation of various HPV vaccination program worldwide.

Cervical cancer has been considered as one of the most common cancers in women (15-44 years) globally, but the advent of the human papilloma virus (HPV) vaccine has raised the anticipation that eradication of cervical carcinoma might be achieved in the near future as several prophylactic cervical carcinoma vaccines have already been currently licensed in various countries. Countries should devise strategies, practices and policies to attain and sustain higher levels of HPV immunization coverage as still 68% countries have introduced HPV vaccine in their national immunization programs even after 17 years following the licensure of the first prophylactic HPV vaccine. A comprehensive literature analysis was conducted using various databases and search engines, to include the most relevant research articles and data available and critically discussed the operational gaps that need to be answered to achieve adequate coverage of HPV vaccination. The present review highlights the existing HPV vaccination strategies, unmet needs and challenges needed to be addressed for proper implementation framework as well as the collaborations required to achieve decent vaccination coverage. Well-coordinated vaccination strategy with focus on adolescent girls and if possible, boys can lead to dramatic impact on disease reduction around the world.

Mucosal Immunity to Poliovirus in Children 0-15 Years of Age: A Community-Based Study in Karachi, Pakistan in 2019.

This study assesses poliovirus type 1 (PV1) immunity in children to inform the contribution of mucosal immunity in and prevention of poliovirus circulation. A community-based study was conducted in periurban Karachi, Pakistan. Randomly selected children (0-15 years of age) received oral poliovirus vaccine (OPV) challenge dose. Blood and stool samples were collected at several time points and evaluated for polio-neutralizing antibodies and serotype-specific poliovirus, respectively. Eighty-one of 589 (14%) children excreted PV1 7 days post-OPV challenge; 70 of 81 (86%) were seropositive at baseline. Twelve of 610 (2%) were asymptomatic wild poliovirus type 1 (WPV1) excretors. Most poliovirus excretors had humoral immunity, suggesting mucosal immunity in these children likely waned or never developed. Without mucosal immunity, they are susceptible to poliovirus infection, shedding, and transmission. Asymptomatic WPV1 excretion suggests undetected poliovirus circulation within the community.

PvDBPII elicits multiple antibody-mediated mechanisms that reduce growth in a Plasmodium vivax challenge trial

The receptor-binding domain, region II, of the Plasmodium vivax Duffy binding protein (PvDBPII) binds the Duffy antigen on the reticulocyte surface to mediate invasion. A heterologous vaccine challenge trial recently showed that a delayed dosing regimen with recombinant PvDBPII SalI variant formulated with adjuvant Matrix-MTM reduced the in vivo parasite multiplication rate (PMR) in immunized volunteers challenged with the Thai P. vivax isolate PvW1. Here, we describe extensive analysis of the polyfunctional antibody responses elicited by PvDBPII immunization and identify immune correlates for PMR reduction. A classification algorithm identified antibody features that significantly contribute to PMR reduction. These included antibody titre, receptor-binding inhibitory titre, dissociation constant of the PvDBPII-antibody interaction, complement C1q and Fc gamma receptor binding and specific IgG subclasses. These data suggest that multiple immune mechanisms elicited by PvDBPII immunization are likely to be associated with protection and the immune correlates identified could guide the development of an effective vaccine for P. vivax malaria. Importantly, all the polyfunctional antibody features that correlated with protection cross-reacted with both PvDBPII SalI and PvW1 variants, suggesting that immunization with PvDBPII should protect against diverse P. vivax isolates.

Avian Influenza in Low and Middle-Income Countries (LMICs): Outbreaks, Vaccination Challenges and Economic Impact

Avian Influenza in Low and Middle-Income Countries (LMICs): Outbreaks, Vaccination Challenges and Economic Impact

Overcoming Challenges in COVID-19 Vaccination among Ethnic Minority Groups in Bangladesh: A Qualitative Exploration

Overcoming Challenges in COVID-19 Vaccination among Ethnic Minority Groups in Bangladesh: A Qualitative Exploration

Navigating Japan's COVID-19 Vaccination Challenges: A Shift in Legal Classification and the Opt-out System.

On January 20, 2023, the Japanese government announced easing the legal handling of the novel coronavirus disease 2019 (COVID-19) under its Infectious Diseases Control Act, effective May 8, 2023. While free vaccines will continue in fiscal year 2023, the future of mass vaccinations remains uncertain. The opt-out system, wherein local governments schedule vaccinations on behalf of the residents, may potentially alleviate issues associated with the currently adopted opt-in approach, such as procedural intricacies and scheduling difficulties, thereby facilitating the recovery of vaccination rates and simultaneously addressing vaccine wastage concerns. Given that COVID-19 still presents a substantial risk to specific groups, such as the elderly, recognizing the benefits of the opt-out system and the ethical and geographical challenges it poses is essential. With the collaboration of local governments and healthcare institutions, ongoing surveillance and scientific assessment are indispensable.

Breaking the vaccination challenges to fight measles in Ethiopia

Breaking the vaccination challenges to fight measles in Ethiopia

IgG Subclass Deficiency

Immunoglobulin G subclass deficiency has been diagnosed in 25% of patients presenting with recurrent infections. Similar to other primary immunodeficiencies, it is commonly overlooked or misdiagnosed. The diagnosis includes documentation of a decreased level of one or more subclasses in conjunction with an inadequate response to a vaccine challenge. Understanding the specific actions of the four subclasses allows the clinician to direct the evaluation and define a treatment program. Several subclass deficiencies are also associated with other disease states. Diagnosis of this entity will limit patient morbidity and allow for more rapid identification of other potentially life-altering illnesses.

Clinical Challenges of the COVID-19 Vaccines: Frequency of Serious Adverse Events After Immunization in Hospitalized Patients

Background and aims: Today, the role of coronavirus disease 19 (COVID-19) vaccines in preventing the disease and reducing the severity of the disease is undeniable; however, there is a possibility of serious adverse events following immunization (sAEFI) that might be life-threatening. The present study was designed to identify the frequency of the most common sAEFI in hospitalized people after receiving the COVID-19 vaccine in the south of Iran. Methods: This cross-sectional study was conducted in 2022. In total, since the start of the COVID-19 vaccination program in the city of Larestan, in the south of Iran, a total of 68 sick people have been hospitalized due to complications caused by the vaccine. The research tool of the present study was a standard checklist called the sAEFI of the COVID-19 vaccine. Results: A total of 68 hospital cases were reviewed. The mean age of the individuals with sAEFI was 59.78±12.70 years, and 21 (56.8%) of them were females. Acute respiratory distress syndrome (ARDS) was the most common 24 (64.9%) sAEFI. Based on the results, 2 (5.4%) had acute coronary syndrome (ACS), 2 (5.4%) had Guillain-Barré syndrome, and 2 (5.4%) had a stroke. Conclusion: It can be mentioned that there is always a possibility of sAEFI, but its frequency in the general population is extremely rare. However, the most common sAEFIs included adverse drug reactions, stroke, and Guillain-Barré syndrome. The readiness of health care staff for early detection of possible sAEFI can be effective in reducing the severity of the sAEFI.

Renewing nurses’ commitment to the global challenge of childhood vaccination after the COVID-19 pandemic

Renewing nurses’ commitment to the global challenge of childhood vaccination after the COVID-19 pandemic

Effectiveness and impact of covid-19 response and vaccination challenges in Namibia: A systematic review.

Namibia, as with many countries around the world is experiencing devastating impact of Covid-19 disease on the economy, psycho-social interactions, and well-being of the populace. These countries implemented several measures to limit the spread of the virus responsible for the severe acute respiratory syndrome (SARS-CoV-2). Namibia also put measures in place to curtail the spread and fatalities due to the virus. However, the nature and implementation strategies of Public Health regulations seriously have impact on preventing the spread and curtailing fatalities arising from the virus. This article presents a report on the effectiveness and impact of Public Health measures instituted by the Health Authority towards curtailing the scourge of covid-19 on the general populace. Elements of the PRISMA protocol was utilised in the review which enabled the synthesis of data on focused area. Multifaceted databases on covid-19 such as Scopus, Science Direct, Google Scholar, World Health Organisation and the Ministry of Health and Social Services of Namibia (MoHSS) among others was used. A steady increase in covid-19 infection at an average rate of eleven (11) per day was noted in the country up till June 2021. Highest rate was linked to densely populated regions of Erongo and Khomas. Control measures for infection prevention and vaccination drive was ineffective majorly as a result of misinformation. A paradigm shift of enhanced interaction with local populace for effective information dissemination is required towards limiting the scourge of the virus and hence, saving of lives.