Vaccines, Volume 11, Issue 8 (August 2023) – 116 articles

Background: Multiple COVID-19 vaccines have been approved for use in adolescents; these vaccines play a critical role in limiting the transmission and impact of COVID-19. This systematic review aims to summarize the willingness of adolescents aged 10 to 19 years to receive the COVID-19 vaccination and the factors influencing their decision. Methods: A search of literature published between January 2018 and August 2022 was performed in Medline©, EMBASE©. and CINAHL© electronic databases. Studies published in English that assessed adolescents’ intentions to receive the COVID-19 vaccine were included. Qualitative studies and those unrelated to the COVID-19 vaccine were excluded. The study was conducted based on the PRISMA guidelines. Results: Of the 1074 articles retrieved, 13 were included in the final review. Most studies were conducted in the US (n = 3) and China (n = 3). The pooled prevalence of COVID-19 vaccine acceptance among adolescents was 63% (95% CI: 52–73%). Factors influencing intent to vaccinate were divided into five categories: “Socio-demographic determinants”; “Communication about COVID-19 pandemic and vaccination”; “COVID-19 vaccine and related issues”; “COVID-19 infection and related issues” and “Other determinants”. The enablers were sociodemographic factors including older age, higher education level, good health perception, and parental norms in terms of parental vaccination acceptance; perceived vaccine effectiveness and safety; a desire to protect themselves and others; recent vaccination; and anxiety. The barriers were concerns over vaccine effectiveness, safety, and long-term side effects; low perceived necessity and risk of infection; and needle phobia. Conclusions: This review highlighted that adolescents’ intent to vaccinate is driven by a desire to protect themselves and others. However, concerns over vaccine effectiveness, safety, and long-term side effects hinder COVID-19 vaccine uptake. To improve vaccination acceptance, policymakers should address adolescents’ concerns via more targeted public health messaging, while schools should leverage peer norms to positively influence vaccination intent. Full article

Background/Objective: Little is known about the impact of the COVID-19 pandemic on mortality from COPD at the population level. The objective was to investigate COPD-related mortality throughout different epidemic waves in Italy before and after the vaccination campaign, which started in late December 2020 and initially targeted the population aged ≥80 years. Methods: Death certificates of residents in Veneto (Northeastern Italy) aged ≥40 years between 2008 and 2021 were analyzed. Age-standardized morality rates were computed for death certificates with any mention of COPD. Generalized estimating equation (GEE) models were fitted to estimate the expected mortality during the pandemic. The results were stratified by age groups of 40–79 and ≥80 years, main comorbidities, and place of death. Results: COPD was mentioned in 3478 death certificates in 2020 (+14% compared to the 2018–2019 average) and in 3133 in 2021 (+3%). Age-standardized mortality rates increased in all age and sex groups in 2020; in 2021, mortality returned to pre-pandemic levels among the elderly but not in the population aged 40–79 years (+6%). GEE models confirmed this differential trend by age. COPD-related mortality peaks were observed, especially in the first pandemic waves, with COVID-19 identified as the underlying cause of death in a relevant proportion (up to 35% in November 2020–January 2021). Mortality with comorbid diabetes and hypertensive diseases slightly increased during the pandemic. Conclusion: COPD-related mortality increased at the beginning of the pandemic, due to deaths from COVID-19. The start of the vaccination campaign was associated with an important decline in COPD-related mortality, especially among the elderly, who first benefited from COVID-19 vaccines. The study findings show the role of mass vaccination in reducing COPD-related deaths during the later phases of the pandemic. Full article

The numerous influenza infections that occur every year present a major public health problem. Influenza vaccines are important for the prevention of the disease; however, their effectiveness against infection can be suboptimal. Particularly in the elderly, immune induction can be insufficient, and the vaccine efficacy against infection is usually lower than that in young adults. Vaccine efficacy can be improved by the addition of adjuvants, and an influenza vaccine with an oil-in-water adjuvant MF59, FLUAD, has been recently licensed in the United States and other countries for persons aged 65 years and older. Although the adverse effects of adjuvanted vaccines have been a concern, many adverse effects of currently approved adjuvanted influenza vaccines are mild and acceptable, given the overriding benefits of the vaccine. Since sufficient immunity can be induced with a small amount of vaccine antigen in the presence of an adjuvant, adjuvanted vaccines promote dose sparing and the prompt preparation of vaccines for pandemic influenza. Adjuvants not only enhance the immune response to antigens but can also be effective against antigenically different viruses. In this narrative review, we provide an overview of influenza vaccines, both past and present, before presenting a discussion of adjuvanted influenza vaccines and their future. Full article

Background: Routine human papillomavirus (HPV) vaccine uptake continues to be suboptimal since its recommendation in 2006 for girls and in 2011 for boys. This paper aims to review published quality improvement (QI) methodologies on interventions to improve HPV vaccine uptake among adolescents. Methods: Science Direct and Scopus databases were searched for QI initiatives evaluating the effect of multimodal interventions to improve HPV vaccination rates (initiation and/or completion of series) among adolescents. Studies that included an outcome of interest among adolescents aged 10 to 18 years old were included. Two investigators worked independently to screen for potential articles and a designated investigator extracted data on study characteristics and evaluated the outcomes. Results: A preliminary search yielded a total of 523 articles and 13 were included in the final analysis. Common strategies were provider-specific (i.e., webinar, telementoring, train-the-trainer approach) and patient- and/or parent-specific interventions (i.e., reminder emails, phone calls and text messages, social events), with an emphasis on education and knowledge empowerment. System-level interventions such as policy changes and revised protocols were less commonly prescribed despite being associated with a more significant weight on the overall outcome. Conclusions: Creative, sustainable, and economical multilevel interventions that focus not only on provider training and public education but also incorporate local policies and system enhancements can substantially improve HPV vaccination coverage among adolescents. Full article

A better understanding of population-level factors related to measles case fatality is needed to estimate measles mortality burden and impact of interventions such as vaccination. This study aimed to develop a conceptual framework of mechanisms associated with measles case fatality ratios (CFRs) and assess the scope of evidence available for related indicators. Using expert consultation, we developed a conceptual framework of mechanisms associated with measles CFR and identified population-level indicators potentially associated with each mechanism. We conducted a literature review by searching PubMed on 31 October 2021 to determine the scope of evidence for the expert-identified indicators. Studies were included if they contained evidence of an association between an indicator and CFR and were excluded if they were from non-human studies or reported non-original data. Included studies were assessed for study quality. Expert consultation identified five mechanisms in a conceptual framework of factors related to measles CFR. We identified 3772 studies for review and found 49 studies showing at least one significant association with CFR for 15 indicators (average household size, educational attainment, first- and second-dose coverage of measles-containing vaccine, human immunodeficiency virus prevalence, level of health care available, stunting prevalence, surrounding conflict, travel time to major city or settlement, travel time to nearest health care facility, under-five mortality rate, underweight prevalence, vitamin A deficiency prevalence, vitamin A treatment, and general malnutrition) and only non-significant associations for five indicators (antibiotic use for measles-related pneumonia, malaria prevalence, percent living in urban settings, pneumococcal conjugate vaccination coverage, vitamin A supplementation). Our study used expert consultation and a literature review to provide additional insights and a summary of the available evidence of these underlying mechanisms and indicators that could inform future measles CFR estimations. Full article

The emergence of new coronavirus variants and evidence of waning immunity offered by COVID-19 vaccines draw attention to the need for regular vaccination. Vaccine hesitancy is one of the top ten threats to global health. There is a dearth of knowledge on people’s hesitancy to take regular COVID-19 vaccines. This study aimed to investigate the prevalence and determinants of hesitancy for regular COVID-19 vaccination. A population-based, random telephone survey was performed in Hong Kong in April 2022 (n = 1213). The age-standardized hesitancy rate for regular COVID-19 vaccines among Hong Kong adults was 39.4% (95% CI = 35.3–44.1%), exhibiting a sloping S-shape with age. Regression analyses revealed that females, young adults, self-perceived fair/bad health, low COVID-19 vaccine uptake, and believing there are better ways for prevention of infection were positive determinants of hesitancy for regular vaccination. Vaccine confidence, perceived severity and availability, trust in manufacturers and government, and civic duty inclination were negative determinants. Tailored vaccine promotions are needed for females, young adults, and people perceiving poor health and receiving fewer doses. Information on infection severity, vaccine availability, and trust in suppliers, products, and governments are key attitude-change facilitators to decrease hesitancy for regular COVID-19 vaccination and cope with future pandemics. Full article

COVID-19 vaccines are an effective public health intervention to reduce COVID-19-related morbidity and mortality. Given that pregnant and lactating women have a higher risk of severe COVID-19 complications, it is paramount to understand the factors that inform vaccine decision-making among this population. In this study, we sought to identify facilitators and barriers to COVID-19 vaccine acceptance and vaccine promotion in pregnant and lactating women in Bangladesh. We conducted 40 in-depth interviews with 12 pregnant women, 12 lactating women, and 16 health workers from one urban and four rural communities in Bangladesh. We used a grounded theory approach to identify emerging themes. Our results suggest that health workers and religious leaders played key roles in promoting COVID-19 vaccines in this population. Further, we found that the culture of trust in public health authorities and the existing vaccine infrastructure facilitated vaccine promotion. However, changes in vaccine eligibility and myths and rumors acted as both facilitators and barriers to vaccine promotion within our study. It is crucial that maternal immunization vaccine promotion efforts push pregnant and lactating women toward vaccine acceptance to protect the health of mothers and their babies. Additionally, as new maternal vaccines are developed and licensed, understanding how to best promote vaccines within this group is paramount. Full article

In May 2023, the U.S. FDA advisors endorsed Pfizer’s pregnancy-administered vaccine (branded ABRYSVO) to protect infants from respiratory syncytial virus (RSV) infection. Vaccination can reduce the burden of RSV-related respiratory disease, with previous studies showing its substantial medical and financial burden in Jordan. However, pregnant women may exhibit hesitancy to get vaccinated due to concerns about potential risks to themselves or their fetuses. This study aimed to assess the acceptance of the RSV vaccine among young females and identify the determinants influencing their decision using a newly constructed instrument. A survey instrument was developed and validated, comprising 26 items to measure RSV vaccine acceptance. A cross-sectional study design was employed, with data collection from a sample of females aged 18 to 45 residing in Jordan during 5–6 July 2023, using a convenient approach via an online distributed questionnaire. The final study sample comprised 315 respondents, with 67.6% who have heard of RSV before the study. If the vaccine was safe, effective, and provided freely, 70.2% showed willingness to get the RSV vaccine, 15.2% resisted, and 14.6% were hesitant. Principal component analysis identified six internally consistent sub-scales with the following suggested themes: Advice, Burden, Conspiracy, Dangers, Efficiency, and Fear, comprising 21 items collectively as assigned as the “ABCDEF” scale for RSV vaccine acceptance. RSV vaccine acceptance in this study was associated with the advice and fear constructs. The validated survey instrument successfully captured important determinants of RSV vaccine acceptance among young females. RSV vaccine promotion efforts should focus on the following: enhancing vaccine education, improving trust in healthcare institutions and providers, reducing burdens through resolving cost issues and focusing on the role of social support, addressing safety concerns, and tailoring communication strategies to effectively promote the benefits of the vaccine. These insights can inform public health policies and interventions aiming to promote RSV vaccination and mitigate the burden of RSV-related diseases among infants. Follow-up studies are recommended with pregnant women as the target group to assess their attitude towards RSV vaccination and to confirm the validity of the conceived ABCDEF survey instrument. Full article

Sierra Leone is a West African country with a population of over 8 million. With more than half of Sierra Leone’s population living in rural areas, it is important to understand rural populations’ access to and attitudes toward the COVID-19 vaccine. In November 2021, the rate of vaccination coverage in Sierra Leone was only 7% for one dose and 4% for two doses. Understanding perspectives of health facility staff and patients can help strengthen future vaccine campaigns. We conducted a cross-sectional study, between March 2022 and May 2022, of clinical staff, non-clinical staff, and adult (>18 years) patients/caregivers attending six Ministry of Health and Sanitation (MoHS) facilities supported by Partners In Health, four in the Kono district and two in the Western Urban Area district, the capital of Sierra Leone. We assessed the opportunity to vaccinate, vaccine uptake, and intention to vaccinate. Out of the 2015 participants, 11.4% were clinical staff, 18.8% were non-clinical staff, and 69.8% were patients/caregivers. Less than half of the patients/caregivers had the opportunity to be vaccinated (42%), and 22% of patients/caregivers were fully vaccinated. Among the unvaccinated population, 44% would refuse a vaccine if offered to them at no cost. Lack of access to COVID-19 vaccines and to official education messaging, especially for patients and caregivers, is still an underlying problem in Sierra Leone for vaccine uptake, rather than a lack of willingness to be vaccinated. Full article

Control of the intracellular parasite Leishmania (L.) requires the activation of strong type 1 cellular immune responses. Towards this goal, in the present study, a multiepitope chimeric protein named LiChimera was encapsulated into cationic liposomes and its protective efficacy against experimental visceral leishmaniasis was investigated. Liposomal LiChimera conferred significant protection against L. infantum as evidenced by the significantly reduced parasite loads in the spleen and liver. Protection detected in Lipo:LiChimera-immunized mice was dependent on the differentiation of long-lasting cellular immune responses and particularly the induction of antigen-specific multifunctional memory CD4⁺ T_H1 and CD8⁺ T cells that persisted during infection, as evidenced by the persistent high production of IFN-γ and IL-2 and proliferation activity. Notably, protected mice were also characterized by significantly low numbers of non-regulatory CD4⁺ T cells able to co-produce IFN-γ and IL-10, an important population for disease establishment, as compared to non-immunized control group. Collectively, these results demonstrate that cationic liposomes containing LiChimera can be considered an effective candidate vaccine against visceral leishmaniasis. Full article

Background: Influenza in pregnancy is associated with elevated morbidity and mortality. Influenza vaccines are safe and effective in pregnancy. There are no Mexican surveys of physicians on knowledge, beliefs, and practices towards influenza and influenza immunization during pregnancy. Methods: A 32-question descriptive survey was conducted, addressing the general knowledge of influenza as well as beliefs and practices regarding influenza vaccination during pregnancy among Mexican physicians responsible for prenatal care, traditionally Obstetricians (OBGYNs) and Family Physicians (FPs). Results: A total of 206 surveys were available, 98 (47.6%) from OBGYNs and 108 (52.4%) from FPs, representing an estimated 2472 daily pregnancy consultations. In total, 54 of the 206 respondents (26.2%) were not aware that influenza is more severe during pregnancy, 106 of the 206 respondents (51.5%) ignored the potential side effects of influenza infection on the fetus, and 56.8% did not know when to vaccinate pregnant women. Pregnancy as a risk factor for developing influenza complications was only known by 99 of the 206 respondents (48.1%), and 6.1% believed that vaccination does not confer protection to the fetus. Conclusions: The current beliefs of Mexican OBGYNs and FPs for both influenza morbidity and mortality, and the importance of influenza vaccination during pregnancy are suboptimal. The drivers of these beliefs should be assessed to improve influenza vaccination recommendations, as knowledge alone is not sufficient. Full article

Elderly care home residents are particularly vulnerable to COVID-19 due to immune-senescence, pre-existing medical conditions, and the risk of transmission from staff and visitors. This study aimed to describe the outcomes of a COVID-19 outbreak in a long-term care facility for elderly persons following the initial vaccination. A single-center, retrospective, observational design was used to analyze the variables associated with hospitalization and death rate by logistic regression. Adjusted odds ratios (aOR) and their 95% confidence intervals (CI) were calculated. Sixty-eight residents received the first dose of the COVID-19 vaccine. Despite being negative six days after vaccination, the performance of a second test 4 days later revealed 51 positives (75.0%) among residents and 18 among workers (56.3%). A total of 65 of the 68 residents (95.58%) had positive results with symptoms, whereas 34.9% required hospitalization, and 25.8% died. The best-fitting model to explain the distribution of cases reflects three points at the time of infection.. The time from vaccination to symptom onset explains the hospitalization and mortality rates since a day elapsed halves the risk of hospitalization (aOR = 0.57; CI = 0.38−0.75) and the risk of death by a quarter (aOR = 0.74; CI = 0.63−0.88). Nursing homes present an elevated risk of transmission and severity of SARS-CoV-2 infection. Although vaccination reduces the risk of hospitalization and death, extreme prevention and control measures are essential in these institutions despite the high vaccination coverage. Full article

Given the high amount of information available on social media, the paper explores the degree of vaccine hesitancy expressed in English tweets posted worldwide during two different one-month periods of time following the announcement regarding the discovery of new and highly contagious variants of COVID-19—Delta and Omicron. A total of 5,305,802 COVID-19 vaccine-related tweets have been extracted and analyzed using a transformer-based language model in order to detect tweets expressing vaccine hesitancy. The reasons behind vaccine hesitancy have been analyzed using a Latent Dirichlet Allocation approach. A comparison in terms of number of tweets and discussion topics is provided between the considered periods with the purpose of observing the differences both in quantity of tweets and the discussed discussion topics. Based on the extracted data, an increase in the proportion of hesitant tweets has been observed, from 4.31% during the period in which the Delta variant occurred to 11.22% in the Omicron case, accompanied by a diminishing in the number of reasons for not taking the vaccine, which calls into question the efficiency of the vaccination information campaigns. Considering the proposed approach, proper real-time monitoring can be conducted to better observe the evolution of the hesitant tweets and the COVID-19 vaccine hesitation reasons, allowing the decision-makers to conduct more appropriate information campaigns that better address the COVID-19 vaccine hesitancy. Full article

Immunization against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has significantly limited the spread of coronavirus disease 2019 (COVID-19) and reduced the associated complications, especially mortality. To prolong immunity, an immune booster was implemented. We evaluated the role of SARS-CoV-2 infection history in the vaccination schedules of kidney and liver transplant recipients and patients with chronic kidney disease (CKD). To this end, we retrospectively analyzed the data of 78 solid organ transplantation (SOT) recipients and 40 patients with immunoglobulin A (IgA) nephropathy as representatives of the CKD group. Patients received two or three doses of the BNT162b2 vaccine. At the follow-up, antibody (Ab) titer, graft function, COVID-19 history, and patients’ clinical condition were assessed. Ab level was higher after two doses in patients with a COVID-19 history over three doses in patients with no COVID-19 history. Compared to three doses, subjects who were administered two doses had a longer median time to infection. Positive antibodies, in response to the third dose, were not observed in up to 8.4% of SOT patients. The results show that the vaccination schedule should take into account the vaccine response rate and COVID-19 history. So-called hybrid immunity appears to be most efficient at providing humoral responses against SARS-CoV-2 infection in immunocompromised patients. Full article

The Public Health Agency of Canada recommends that 80% of high-risk persons, including adults aged ≥65 years and 18–64 years with certain comorbidities, be vaccinated against influenza. During the 2022–2023 influenza season, we conducted an online survey of 3000 Canadian residents aged ≥18 years randomly recruited from the Léger Opinion (LEO) consumer panel to assess knowledge and perceptions about influenza vaccination as well as survey self-reported vaccination rates. Overall, 47.3% received an influenza vaccination during the 2022–2023 season. Vaccination rates among persons aged 18–64 years with high-risk medical conditions (n = 686) and among adults aged ≥65 years (n = 708) were 46.4% and 77.4%, respectively; 77.8% and 88.5%, respectively, believed influenza vaccination was important for people at high risk from influenza. Only 35.8% of adults aged 18–64 years with comorbidities were aware of being at high risk; 66.0% of this group was vaccinated against influenza, compared with 37.0% of those unaware of being at high-risk. During 2022–2023, 51.3% of people aged ≥65 years and 43.0% of people aged 18–64 years with comorbidities discussed influenza vaccination with healthcare providers. These findings suggest gaps in education regarding the importance of influenza vaccination among people at risk of influenza complications. Full article

Rabies encephalitis is a fatal zoonotic viral disease caused by the neurotropic rabies virus. It remains a major public health concern as it causes almost 100% fatality and has no effective medication after the onset of the disease. However, this illness is preventable with the timely administration of effective post-exposure prophylaxis (PEP) consisting of the rabies vaccine and passive immune globulins (HRIG and ERIG). Recently, conventional PEP has been shown to have many limitations, resulting in little support for these expensive and heterologous globulins. Monoclonal antibody (mAb) production via recombinant technology in animal and human cell cultures, as well as a plant-based platform, was introduced to overcome the costly and high-tech constraints of former preparations. We used transient expression technology to produce two mAbs against the rabies virus in Nicotiana benthamiana and compared their viral neutralizing activity in vitro and in vivo. The expression levels of selective mAbs E559 and 62-71-3 in plants were estimated to be 17.3 mg/kg and 28.6 mg/kg in fresh weight, respectively. The plant-produced mAbs effectively neutralized the challenge virus CVS-11 strain in a cell-based RFFIT. In addition, the combination of these two mAbs in a cocktail protected hamsters from rabies virus infection more effectively than standard HRIG and ERIG. This study suggests that the plant-produced rabies antibody cocktail has promising potential as an alternative biological to polyclonal RIG in rabies PEP. Full article

Data on immunogenicity, immune response persistency, and safety of COVID-19 boosters in patients with comorbidities are limited. Therefore, we aimed to evaluate three different boosters’ immunogenicity and safety in individuals with at least one underlying disease (UD) (obesity, hypertension, and diabetes mellitus) with healthy ones (HC) who were primed with two doses of the BBIBP-CorV vaccine and received a booster shot of the same priming vaccine or protein subunit vaccines, PastoCovac Plus or PastoCovac. One hundred and forty subjects including sixty-three ones with a comorbidity and seventy-seven healthy ones were enrolled. The presence of SARS-CoV-2 antibodies was assessed before the booster injection and 28, 60, 90, and 180 days after it. Moreover, the adverse events (AEs) were recorded on days 7 and 21 postbooster shot for evaluating safety outcomes. Significantly increased titers of antispike, antiRBD, and neutralizing antibodies were observed in both UD and HC groups 28 days after the booster dose. Nevertheless, the titer of antispike IgG and anti-RBD IgG was lower in the UD group compared to the HC group. The long-term assessment regarding persistence of humoral immune responses showed that the induced antibodies were detectable up to 180 days postbooster shots though with a declined titer in both groups with no significant differences (p > 0.05). Furthermore, no significant difference in antibody levels was observed between each UD subgroup and the HC group, except for neutralizing antibodies in the hypertension subgroup. PastoCovac Plus and PastoCovac boosters induced a higher fold rise in antibodies in UD individuals than BBIBP-CorV booster recipients. No serious AEs after the booster injection were recorded. The overall incidence of AEs after the booster injection was higher in the UD group than the HC group among whom the highest systemic rate of AEs was seen in the BBIBP-CorV booster recipients. In conclusion, administration of COVID-19 boosters could similarly induce robust and persistent humoral immune responses in individuals with or without UD primarily vaccinated with two doses of the BBIBP-CorV. Protein-based boosters with higher a higher fold rise in antibodies and lower AEs in individuals with comorbidities might be considered a better choice for these individuals. Full article

Background: Low coverage of influenza vaccination in nursing home (NH) staff may be attributed to factors such as vaccine confidence (VC) and vaccine literacy (VL). Our study aimed to evaluate the role of VL and VC in predicting the intention to get the influenza vaccine in a sample of employees of NHs in Tuscany, Italy. Methods: Data from staff members in Tuscany were collected using an online questionnaire that examined influenza vaccination history, intentions, demographic information, health status, and VL. Statistical analyses explored the relationships between VC, VL, and vaccination intentions. Results: The study included 1794 respondents, (86.3%) and assistants/aides (58.1%), with a median age of 46 years. The intention to get vaccinated was significantly higher among those with health risk conditions, and there was a positive association between VC and VL, specifically its interactive/critical component. The mediation analysis showed that VC completely mediated the relationship between VL and the intention to get vaccinated, with significant effects observed in different subgroups. Conclusions: VC is a key factor that mediates the effect of VL on vaccine intention. These results suggest that interventions aimed at improving VL alone may not be sufficient to increase vaccine uptake unless VC is also addressed. Full article

Background: Evidence on SARS-CoV-2 mRNA vaccination under siponimod treatment is rare. Methods: AMA-VACC is a prospective, open-label clinical study on SARS-CoV-2 mRNA vaccination during ongoing siponimod treatment (cohort 1), during siponimod interruption (cohort 2), or during treatment with other disease-modifying therapies or without therapy (cohort 3). SARS-CoV-2-specific antibodies and T-cell reactivity were measured six months after the initial vaccination and one month after the booster. Results: 41 patients were recruited into cohort 1 (n = 17), cohort 2 (n = 4), and cohort 3 (n = 20). Seroconversion for SARS-CoV-2 neutralizing antibodies was reached by 50.0%, 100.0%, and 90.0% of patients at month 6 and by 81.3%, 100.0%, and 100.0% one month after booster (cohorts 1, 2, and 3, respectively). Antibody levels in cohort 1 increased after the booster compared to month 6 but remained lower compared to cohorts 2 and 3. T-cell responses were seen in 28.5%, 25.0%, and 73.7% at month 6 and in 28.6%, 50.0%, and 83.3% after the booster (cohorts 1, 2, and 3, respectively). In cohort 1, the extent of T-cell response was lower at month 6 compared to cohorts 2 and 3 but reached almost similar levels after the booster. Conclusions: The antibody and T-cell responses support SARS-CoV-2 (booster) vaccines in siponimod-treated patients. Full article

Grass carp reovirus (GCRV) seriously threatens the grass carp (Ctenopharyngodon idella) industry. Prophylactic GCRV vaccines prepared by virus-like particle (VLP) assembly biotechnology can improve effectiveness and safety. The highly immunogenic candidate antigens of GCRV vaccines that have been generally considered are the outer capsid proteins VP4, VP56, and VP35. In this study, VP4, VP56, and VP35 were expressed in an Escherichia coli expression system and a Pichia pastoris expression system. The successful assembly of uniform, stable, and non-toxic VP4/VP56/VP35 VLPs was confirmed through various assays. After vaccination and GCRV infection, the survival rate in the VLPs + adjuvant Astragalus polysaccharide (APS) group was the highest (62%), 40% higher than that in control group (22%). Through the antibody levels, tissue viral load, and antioxidant immunity assays, the P. pastoris VLP vaccine effectively improved IgM levels, alleviated tissue virus load, and regulated antioxidant immune-related indicators. The treatment with P. pastoris VLPs enhanced the mRNA expression of important immune-related genes in the head kidney, as measured by qRT-PCR assay. Upon hematoxylin-eosin staining examination, relatively reduced tissue pathological damage was observed in the VLPs + APS group. The novel vaccine using P. pastoris VLPs as an effective green biological agent provides a prospective strategy for the control of fish viral diseases. Full article

Vaccines are the cornerstone of infectious disease control and prevention. The outbreak of SARS-CoV-2 has confirmed the urgent need for a new approach to the design of novel vaccines. Plant viruses and their derivatives are being used increasingly for the development of new medical and biotechnological applications, and this is reflected in a number of preclinical and clinical studies. Plant viruses have a unique combination of features (biosafety, low reactogenicity, inexpensiveness and ease of production, etc.), which determine their potential. This review presents the latest data on the use of plant viruses with different types of symmetry as vaccine components and adjuvants in cancer immunotherapy. The discussion concludes that the most promising approaches might be those that use structurally modified plant viruses (spherical particles) obtained from the Tobacco mosaic virus. These particles combine high adsorption properties (as a carrier) with strong immunogenicity, as has been confirmed using various antigens in animal models. According to current research, it is evident that plant viruses have great potential for application in the development of vaccines and in cancer immunotherapy. Full article

Since 1 June 2023, a nationwide HPV vaccination program was implemented in Poland. This study aimed to identify factors associated with public awareness of the national HPV vaccination program among adults in Poland and willingness to vaccinate children against HPV. This cross-sectional study was carried out between 14 and 17 July 2023 among 1056 adults in Poland. A self-prepared questionnaire was used. Among the respondents, 51.3% had heard about the free HPV vaccination program. The major source of knowledge on the national HPV vaccination program was TV (62%). Only 31.9% of respondents correctly indicated girls and boys aged 12 and 13 as the HPV-vaccination-eligible population. Willingness to vaccinate children against HPV was declared by 63.3% of respondents. Female gender (OR: 1.42; 95% CI: 1.11–1.81; p < 0.01), age 35–64 years (p < 0.05), having higher education (OR: 1.43; 95% CI: 1.11–1.84; p < 0.01), and living in cities with more than 500,000 residents (OR: 1.51; 95% CI: 1.01–2.28; p < 0.05) were significantly associated with higher odds to hear about the national HPV vaccination program. Age 50 years and over (p < 0.05), having higher education (OR: 1.43; 95% CI: 1.09–1.88; p < 0.05), living in cities with more than 500,000 residents (OR: 1.80; 95% CI: 1.14–2.83; p < 0.05), and no children under 18 in the home (OR: 1.39; 95% CI: 1.01–1.89; p < 0.05) were significantly associated with willingness to vaccinate children against HPV. Full article

(1) Introduction: The Democratic Republic of the Congo (DRC) has one of the largest cohorts of un- and under-vaccinated children worldwide. This study aimed to identify and compare the main reasons for there being zero-dose (ZD) or under-vaccinated children in the DRC. (2) Methods: This is a secondary analysis derived from a province-level vaccination coverage survey conducted between November 2021 and February 2022; this survey included questions about the reasons for not receiving one or more vaccines. A zero-dose child (ZD) was a person aged 12–23 months not having received any pentavalent vaccine (diphtheria–tetanus–pertussis–Hemophilus influenzae type b (Hib)–Hepatitis B) as per card or caregiver recall and an under-vaccinated child was one who had not received the third dose of the pentavalent vaccine. The proportions of the reasons for non-vaccination were first presented using the WHO-endorsed behavioral and social drivers for vaccination (BeSD) conceptual framework and then compared across the groups of ZD and under-vaccinated children using the Rao–Scott chi-square test; analyses were conducted at province and national level, and accounting for the sample approach. (3) Results: Of the 51,054 children aged 12–23 m in the survey sample, 19,676 ZD and under-vaccinated children were included in the study. For the ZD children, reasons related to people’s thinking and feelings were cited as 64.03% and those related to social reasons as 31.13%; both proportions were higher than for under-vaccinated children (44.7% and 26.2%, respectively, p < 0.001). Regarding intentions to vaccinate their children, 82.15% of the parents/guardians of the ZD children said they wanted their children to receive “none” of the recommended vaccines, which was significantly higher than for the under-vaccinated children. In contrast, “practical issues” were cited for 35.60% of the ZD children, compared to 55.60% for the under-vaccinated children (p < 0.001). The distribution of reasons varied between provinces, e.g., 12 of the 26 provinces had a proportion of reasons for the ZD children relating to practical issues that was higher than the national level. (4) Conclusions: reasons provided for non-vaccination among the ZD children in the DRC were largely related to lack of parental/guardian motivation to have their children vaccinated, while reasons among under-vaccinated children were mostly related to practical issues. These results can help inform decision-makers to direct vaccination interventions. Full article

In June 2010, Greece introduced the 13-valent pneumococcal conjugate vaccine (PCV13) for pediatric vaccination and has since observed a large decrease in pneumococcal disease caused by these vaccine serotypes, yet the disease prevalence of non-vaccine serotypes has increased. Two higher-valent conjugate vaccines, a 15-valent (PCV15) and a 20-valent (PCV20), were developed to improve serotype coverage and combat serotype replacement. A decision-analytic model was adapted to the Greek setting using historical pneumococcal disease trends from PCV13 to forecast future clinical and economic outcomes of higher-valent PCVs over a 10-year period (2023–2033). The model estimated outcomes related to invasive pneumococcal disease (IPD), hospitalized and non-hospitalized pneumonia, and otitis media (OM) resulting from a switch in vaccination programs to PCV15 in 2023 or switching to PCV20 in 2024. Cost-effectiveness was evaluated from the third-party payer’s perspective in the Greek healthcare system. Compared to implementing PCV15 one year earlier, switching from PCV13 to PCV20 in 2024 was estimated to be a cost-saving strategy by saving the Greek health system over EUR 50 million in direct medical costs and averting over 250 IPD cases, 54,800 OM cases, 8450 pneumonia cases, and 255 deaths across all ages over a 10-year period. Full article

Background: Despite the low transmission risk of Monkeypox (mpox) in Belarus, this study is vital as it contributes to our understanding of vaccine hesitancy among healthcare professionals (HCPs). It aims to assess vaccination perceptions and evaluate the willingness to pay for the vaccine among Belarusian HCPs, thereby enhancing pandemic preparedness. Methods: in October 2022, a cross-sectional survey-based study was conducted among Belarusian HCPs using a self-administered questionnaire (SAQ). Invitations were disseminated via social media platforms using a snowball sampling method. The SAQ encompassed various categories, including sociodemographic details, medical history, sources of mpox information, perceived and factual mpox knowledge, and perceptions of the mpox vaccine according to the health belief model (HBM), mpox vaccine acceptance and willingness to pay (WTP). Results: while a large proportion of respondents had good knowledge of mpox epidemiology and its clinical manifestations, their awareness of available vaccines and treatment options was limited. Consequently, a significant correlation was found between the history of influenza vaccination and mpox-related knowledge. Furthermore, the study showed that just over half of the participants (51.4%) were willing to receive the mpox vaccine if offered for free, safely, and effectively, with their decision largely influenced by perceived benefits (Spearman’s rho = 0.451) and cues to action (Spearman’s rho = 0.349). However, a considerable degree of hesitancy (30.6%) and resistance (18.1%) towards the mpox vaccine was observed, underscoring the need for targeted interventions to address these issues. Conclusions: this study highlights a significant knowledge gap among Belarusian HCPs about mpox vaccines and treatments, despite a general awareness of the disease’s epidemiology and symptoms, and it underscores the need for targeted interventions to enhance mpox knowledge and vaccine acceptance. Full article

Human papillomavirus (HPV) vaccination has been proven to be the most effective method to prevent cervical cancer. This study aimed to determine the HPV vaccination behavior and preference in Chinese female health care workers. A nationwide cross-sectional study was performed to recruit 15,967 respondents aged 18–45 years from 31 provinces in China’s mainland in 2021. Of them, 30.0% have been vaccinated or have made an appointment. Regardless of actual vaccination status, respondents mostly preferred the 9-valent HPV vaccine (58.6%), followed by 4-valent (15.6%) and 2-valent vaccines (3.1%); additionally, 17.9% did not have a preference. Moreover, health beliefs on HPV and HPV vaccination were measured using a health belief model (HBM) analysis. Six HBM constructs differed significantly by HPV vaccination status. Higher levels of perceived susceptibility (beta = 0.074), perceived benefit (beta = 0.072), self-efficacy (beta = 0.304), and cues to action (beta = 0.039) scales were significantly associated with increasing HPV vaccine uptake. In contrast, perceived severity (beta = −0.019) and perceived barriers (beta = −0.089) were negative factors. In conclusion, HPV vaccine uptake is high in Chinese female health care workers. HBM constructs may be effective in facilitating the improvement and delivery of targeted intervention programs to increase HPV vaccine uptake. Full article

The use of vaccines is one of the key tools in reversing the COVID-19 pandemic; however, various reports reported the low uptake of the vaccines. This study explored the barriers to the COVID-19 vaccine uptake among community members in Tanzania. A qualitative explorative study was conducted in December 2021 and April 2022 in eight regions of Tanzania. Focus group discussions (FGDs) and in-depth interviews (IDIs) were the methods of data collection. A total of 48 FGDs and 32 IDIs were conducted. Participants were aware of the COVID-19 disease and vaccines. The barriers to the COVID-19 vaccine non-uptake included receiving contradicting statements from top government leaders, vaccine preceded the education, myths towards vaccines, the presence of different types of vaccines, the process of getting the vaccine, the influence of social media and random people from the community, and vaccine conflicting religious beliefs. Despite being aware of the vaccine, the uptake of the COVID-19 vaccine is still low. Interventions that focus on increasing community knowledge about COVID-19 vaccines and addressing myths about the vaccines are needed. Full article

Vaccine hesitancy has been a contentious issue even before the pandemic. The COVID-19 crisis has further amplified vaccine hesitancy, with worries about adverse effects, cultural and religious beliefs, and misinformation on social media. In dermatology, patients with pre-existing skin conditions may have specific concerns about the impact of the vaccine on their skin health. Factors such as cutaneous reactions, potential flares of underlying conditions, and fears of psoriasis worsening post-vaccination contribute to vaccine hesitancy. Healthcare professionals, including dermatologists, play a crucial role in addressing vaccine hesitancy by providing accurate information, addressing concerns, and understanding the psychological impact on patients. The concept of vaccine fatigue is also explored, noting the challenges in sustaining vaccine acceptance over time, especially with regards to booster vaccinations. Overcoming vaccine hesitancy requires trust-building, effective communication strategies, and collaboration between healthcare workers and non-healthcare individuals to combat misinformation. By recognizing and addressing psychological factors, dermatologists can increase vaccine acceptance and improve public health efforts. Full article

Vaccination is an efficient approach to preventing influenza virus infections. Recently, we developed influenza A and B virus vaccine backbones that increased the yield of several vaccine viruses in Madin–Darby canine kidney (MDCK) and African green monkey kidney (Vero) cells. These vaccine backbones also increased viral replication in embryonated chicken eggs, which are the most frequently used platform for influenza vaccine manufacturing. In this study, to further increase the viral titers in embryonated chicken eggs, we introduced random mutations into the ‘internal genes’ (i.e., all influenza viral genes except those encoding the hemagglutinin and neuraminidase proteins) of the influenza A virus high-yield virus backbone we developed previously. The randomly mutated viruses were sequentially passaged in embryonated chicken eggs to select variants with increased replicative ability. We identified a candidate that conferred higher influenza virus growth than the high-yield parental virus backbone. Although the observed increases in virus growth may be considered small, they are highly relevant for vaccine manufacturers. Full article