Sociodemographics, behaviour and knowledge of first South African HPV-vaccine recipients.

BACKGROUND:  Infection with the human papillomavirus (HPV) is a necessary cause of cervical cancer and is one of the most prevalent sexually transmitted infections worldwide. Primary prevention strategies target reducing HPV acquisition through vaccination, limiting exposure (e.g. delayed sexual debut, barrier contraception) and health education focusing on sexual behaviour and tobacco use. METHODS:  The ImmunoVACCS study, conducted from 2019 to 2022 in two provinces in South Africa, examined sociodemographic characteristics, sexual practices, and knowledge of cervical cancer and the HPV vaccine among young female vaccine recipients. It encompassed participants from the previously conducted vaccine implementation trials, VACCS 1 and VACCS 2 (2011-2014). Recruitment involved telephonic contact with eligible potential participants. Data were collected through self-administered questionnaires. RESULTS:  One hundred and eleven participants took part in the current study (median age: 20 years; age range: 16-22 years). Most sexually active participants had their first engagement in secondary school (96.2%), and 77.2% used contraception during their last sexual activity. Knowledge gaps were evident, with only 13.5% recognising cervical cancer's cervix origin and 3.6% attributing it to a virus. Despite this, 70.3% had heard of a vaccine for cervical cancer. Less than half knew about the importance of regular Pap smears (49.5%), vaccine protection (44.1%) or condom use (20.7%) against HPV and cervical cancer. CONCLUSION:  The current study demonstrates that young women still lack complete information on cervical cancer and its risk factors even after receiving health education linked with vaccination.Contribution: This study underscores the necessity of ongoing education about HPV, its risks and preventive measures among young women to combat cervical cancer.

Glycoconjugates: Advances in modern medicines and human health.

Glycans and their glycoconjugates are complex biomolecules that are crucial for various biological processes. Glycoconjugates are found in all domains of life. They are covalently linked to key biomolecules such as proteins and lipids to play a pivotal role in cell signaling, adhesion, and recognition. The diversity of glycan structures and the associated complexity of glycoconjugates is the reason for their role in intricate biosynthetic pathways. Glycoconjugates play an important role in various diseases where they are actively involved in the immune response as well as in the pathogenicity of infectious diseases. In addition, various autoimmune diseases have been linked to glycosylation defects of different biomolecules, making them an important molecule in the field of medicine. The glycoconjugates have been explored for the development of therapeutics and vaccines, representing a breakthrough in medical science. They also hold significance in research studies to understand the mechanisms behind various biological processes. Finally, glycoconjugates have found an emerging role in various industrial and environmental applications which have been discussed here.

Examining the immunological responses to COVID-19 vaccination in multiple myeloma patients: a systematic review and meta-analysis.

BACKGROUND: Impaired immune response in multiple myeloma renders the patients vulnerable to infections, such as COVID-19, and may cause worse response to vaccines. Researchers should analyze this issue to enable the planning for special preventive measures, such as increased booster doses. Therefore, this meta-analysis aimed to evaluate the response and efficacy of COVID-19 vaccines in patients with multiple myeloma. METHODS: This meta-analysis followed PRISMA 2020 guidelines, conducting a comprehensive database search using specified keywords. Study selection involved a two-phase title/abstract and full-text screening process. Data extraction was performed by two researchers, and statistical analysis involved meta-analysis, subgroup analysis based on vaccine dosage and study time, random effects meta-regression, and heterogeneity testing using the Q test. RESULTS: The meta-analysis revealed that patients with multiple myeloma (MM) had a lower likelihood of developing detectable antibodies after COVID-19 vaccination compared to healthy controls (Log odds ratio with 95% CI: -3.34 [-4.08, -2.60]). The analysis of antibody response after different doses showed consistent lower seropositivity in MM patients (after first dose: -2.09, [-3.49, -0.69], second: -3.80, 95%CI [-4.71, -3.01], a booster dose: -3.03, [-5.91, -0.15]). However, there was no significant difference in the mean level of anti-S antibodies between MM patients and controls (Cohen's d -0.72, [-1.86, 0.43]). Evaluation of T-cell responses indicated diminished T-cell-mediated immunity in MM patients compared to controls. Seven studies reported clinical response, with breakthrough infections observed in vaccinated MM patients. CONCLUSIONS: These findings highlight the impaired humoral and cellular immune responses in MM patients after COVID-19 vaccination, suggesting the need for further investigation and potential interventions.

Experiences of Malaysian primary healthcare providers with vaccine hesitancy: A qualitative study.

Introduction: Vaccine hesitancy was declared as one of the ten threats to global public health by the World Health Organization in 2019. It undermines the effort towards eradication of vaccine-preventable diseases. Healthcare providers, who are directly involved in vaccination services and vaccine advocacies, are important in combating vaccine hesitancy. Studies have shown that vaccine refusers have various reasons for refusal including distrust towards healthcare providers. Hence, it is important to understand healthcare providers' perspectives. This study aimed to explore primary healthcare providers (PHCPs)' experiences in dealing with vaccine hesitancy. Methods: This qualitative study was conducted among public PHCPs across six states in Malaysia. Purposive and snowball sampling methods were used. Fifteen primary healthcare doctors and nurses underwent in-depth interviews. Recruitment was stopped when data saturation was achieved. Data were thematically analysed. Results: Four themes emerged: 1) views towards vaccination and vaccine hesitancy, 2) disparity in strategies and resources used among PHCPs, 3) fixed-minded vaccine deniers and religious incompatibility: the two towering hurdles and 4) negative impact after encounters with vaccine hesitancy. Conclusion: Malaysian PHCPs encounter negative experiences with vaccine hesitancy, impacting them negatively. These experiences are attributed to the challenges and lack of standardised resources for reference. These findings suggest the development of a more flexible policy, a training module inclusive of all professional roles and a standardised repository of resources for managing vaccine hesitancy.

Measles Vaccine Coverage and Disease Outbreaks: A Systematic Review of the Early Impact of COVID-19 in Low and Lower-Middle Income Countries.

Objectives: We aimed to evaluate changes to measles-containing vaccine (MCV) provision and subsequent measles disease cases in low- and lower-middle income countries (LICs, LMICs) in relation to the COVID-19 pandemic. Methods: A systematic search was conducted of MEDLINE, OVID EMBASE and PubMed records. Primary quantitative and qualitative research studies published from January 2020 were included if they reported on COVID-19 impact on MCV provision and/or measles outbreak rates within LICs and LMICs. Results: 45 studies were included. The change in MCV1 vaccination coverage in national and international regions ranged -13% to +44.4% from pre-COVID time periods. In local regions, the median MCV1 and overall EPI rate changed by -23.3% and -28.5% respectively. Median MCV2 rate was disproportionally impacted in local areas during COVID-interruption time-periods (-48.2%) with ongoing disruption in early-recovery time-periods (-17.7%). 8.9% of studies reported on vaccination status of confirmed measles cases; from these, 71%-91% had received no MCV dose. Conclusion: MCV vaccination coverage experienced ongoing disruption during the recovery periods after initial COVID-19 disruption. Vaccination in local area datasets notably experienced longer-term disruption compared to nationally reported figures.

Vaccimel immunization is associated with enhanced response to treatment with anti-PD-1 monoclonal antibodies in cutaneous melanoma patients - a case reports study.

Cancer vaccines are gaining ground as immunotherapy options. We have previously demonstrated in cutaneous melanoma (CM) patients that adjuvant treatment with VACCIMEL, a mixture of four irradiated CM cell lines co-adjuvanted with BCG and GM-CSF, increases the cellular immune response to melanocyte differentiation antigens, cancer-testis antigens and neoantigens, with respect to basal levels. On the other hand, it is also known that treatment with anti-PD-1 monoclonal antibodies (MAbs), acting on pre-existing tumor-reactive lymphocytes, induces clinical responses in CM patients, albeit in a fraction of treated patients. A combination of both treatments would appear therefore desirable. In this paper, we describe CM patients who, having progressed even years after vaccination, were treated with anti-PD-1 MAbs. In 5/5 of such progressor patients, complete responses were obtained which lasted between 3 and 65+ months. Three of the patients remain disease-free and two recurred. One of the patients passed away after a recurrence of brain metastases. We suggest that clonally expanded reactive lymphocytes induced by VACCIMEL partially remain as memory cells, which may be recalled after tumor recurrence and may foster ulterior activity of anti-PD-1 MAbs.

Evaluation of the immunogenicity of an mRNA vectored Nipah virus vaccine candidate in pigs.

Nipah virus (NiV) poses a significant threat to human and livestock populations across South and Southeast Asia. Vaccines are required to reduce the risk and impact of spillover infection events. Pigs can act as an intermediate amplifying host for NiV and, separately, provide a preclinical model for evaluating human vaccine candidate immunogenicity. The aim of this study was therefore to evaluate the immunogenicity of an mRNA vectored NiV vaccine candidate in pigs. Pigs were immunized twice with 100 µg nucleoside-modified mRNA vaccine encoding soluble G glycoprotein from the Malaysia strain of NiV, formulated in lipid nanoparticles. Potent antigen-binding and virus neutralizing antibodies were detected in serum following the booster immunization. Antibody responses effectively neutralized both the Malaysia and Bangladesh strains of NiV but showed limited neutralization of the related (about 80% amino acid sequence identity for G) Hendra virus. Antibodies were also capable of neutralizing NiV glycoprotein mediated cell-cell fusion. NiV G-specific T cell cytokine responses were also measurable following the booster immunization with evidence for induction of both CD4 and CD8 T cell responses. These data support the further evaluation of mRNA vectored NiV G as a vaccine for both pigs and humans.

Exploring social media influences on vaccine decision-making in parents: a netnography.

Background: Immunization is one of the most significant health initiatives of recent times. Despite this, vaccine hesitancy is increasing and was listed as one of the top 10 threats to global health by the World Health Organization in 2019. A major factor associated with vaccine hesitancy is thought to be the viral spread of misinformation by a small but active anti-vaccination movement. Objectives: The purpose of this study was to explore the influences of social media on vaccine decision-making in parents. Design: This study is part of a larger body of research that explored vaccine decision-making in parents. Other methods included were an online survey and semi-structured interviews. This study investigated the influence of cyberculture on parents in an online environment. Method: This study employed netnography, a form of qualitative inquiry with its roots in ethnography as methodology and a purpose-designed Facebook page as the means of exploring a purpose-designed online community with a particular focus on the culture, belief systems and influences present. Both manual and computer-assisted thematic analyses were used to analyse the data obtained. Results: Three key themes were identified in this study. These included vaccine safety concerns, the emotional debate and COVID-19-specific issues. The results indicated the presence of strong anti-vaccination sentiment combined with an 'infodemic' of conspiracy theories, misinformation and vitriol with the potential to negatively impact parents seeking immunization information. Conclusion: Given the popularity and accessibility of social media and the ready access to misinformation present online, it is evident that parental vaccine decision-making may be impacted adversely. Therefore, it is important that healthcare professionals are aware of this and provide adequate and timely education prior to parents seeking information on social media.

Exploring the influence of social media on vaccine decision-making in parents: a netnography This research explored the impact of Facebook interactions on the vaccine decision-making of parents.

Vaccine Mandates: Weighing the Common Good vs Personal Conscience and Autonomy.

COVID-19 is a serious illness with significant morbidity and mortality. Vaccines to immunize against it were developed in record time. Mandates followed. The question to be considered is when mandates are ethical. Mandates can be used to prevent spread of an infection, prevent overwhelming the healthcare system, or protect public safety, thereby protecting the vulnerable and allowing for full flourishing of the common good. At the same time, one must be careful about respecting autonomy by allowing those who consciences do not allow them to be vaccinated to refuse. Because COVID-19 knowledge is rapidly changing as more information is known and the virus mutates, the conditions under which mandates are ethical change as well. At present, since vaccines prevent severe infection and death in high-risk individuals with added benefit for those who are vaccinated and have a history of infection, mandates can be imposed on those individuals. With an estimated 95% of the US population believed to have been infected and prior history of infection shown to be as effective as vaccination, with immunity lasting at least 500 days, and ability to prevent spread unknown at present but limited at best in the past, the vaccines therefore cannot be ethically mandated for those who are low risk for the versions released September 2023 based on information as of October 2023.

Risk compensation after COVID-19 vaccination: Evidence from vaccine rollout by exact birth date in South Korea.

We utilize the phased rollout of COVID-19 vaccines by exact birth date in South Korea as a natural experiment for testing risk compensation. People may resume face-to-face social activities following vaccination because they perceive lower risk of infection. Applying a regression discontinuity design based on birth date cutoffs for vaccine eligibility, we find no evidence of risk-compensating behaviors, as measured by large, high-frequency data from credit card and airline companies as well as survey data. We find some evidence of self-selection into vaccine take-up based on perception toward vaccine effectiveness and side effects, but the treatment effects do not differ between compliers and never-takers.

Exploring parental perspectives: Maternal RSV vaccination versus infant RSV monoclonal antibody.

Respiratory Syncytial Virus poses a significant global public health threat, particularly affecting infants aged less than one year of age. Recently, two forms of passive immunization against infant RSV have been developed and brought to market; nirsevimab a long-acting monoclonal antibody (mAb) and RSV-PreF, a maternal RSV vaccine. The acceptability and uptake of these products will play a pivotal role in determining the success of any national immunization strategy aimed at safeguarding infants from RSV. It is crucial at this time to reflect on the factors that influence parental decisions surrounding immunization to facilitate more informed discussions, enhance healthcare communication, and contribute to the design of effective RSV prevention strategies that resonate with the concerns and aspirations of parents worldwide.

Association between combination COVID-19-influenza vaccination and long COVID in middle-aged and older Europeans: A cross-sectional study.

The potential impact of combined COVID-19 and influenza vaccination on long COVID remains uncertain. In the present cross-sectional study, we aimed to investigate the plausible association between them in middle-aged and older Europeans based on the Survey of Health, Ageing, and Retirement in Europe (SHARE). A total of 1910 participants were recruited in the analyses. The study outcome was long COVID. Participants were divided into 4 groups through the self-reported status of COVID-19 and influenza vaccination. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. 1397 participants experienced long COVID. After multivariable adjustment, those vaccinated with neither COVID-19 nor influenza vaccine had higher risk of long COVID (OR, 1.72; 95% CI, 1.26-2.35) compared to those vaccinated with both vaccines. Furthermore, adding the 4 statuses of COVID-19 vaccination/influenza vaccination to conventional risk model improved risk reclassification for long COVID (continuous net reclassification improvement was 16.26% [p = .003], and integrated discrimination improvement was 0.51% [p = .005]). No heterogeneity was found in the subgroup analyses (all p-interaction ≥0.05). Our study might provide a strategy for people aged 50 and over to reduce the occurrence of long COVID, that is, to combine the use of the COVID-19 vaccine and influenza vaccines.

Assessing the Knowledge of HPV-Associated Oropharyngeal Squamous Cell Carcinoma, HPV Vaccination, and Practice Scope among Saudi Dental Students in the Western Region.

(1) Background: Human papillomavirus (HPV) infection is significantly associated with oropharyngeal squamous cell carcinoma (HPV-OPSCC), which is one of the fastest-growing cancer incidences globally. Dental practitioners play a crucial role in the primary and secondary prevention of HPV-OPSCC. There is little known about dental students' awareness regarding HPV-OPSCC and HPV vaccination, as well as their intention to promote 'primordial prevention' among their patients. HPV vaccine, and the extent of their professional responsibilities. (2) Methods: This cross-sectional study was conducted in the western region of Saudi Arabia and involved undergraduate dental students (n = 688) from six public and private dental schools. Participants were requested to complete a sequential-section anonymous online survey, with 257 successfully completing all sections of the questionnaire. The association between participant characteristics and HPV-OPSCC, HPV vaccination awareness ratings, and perceived engagement in prevention were analyzed using ANOVA and chi-squared testing. A binary logistic regression analysis was conducted to examine the variables linked to these outcomes. (3) Results: Generally, the overall level of awareness of HPV-OPSCC and HPV vaccination was acceptable, with an average score of 53.44 ± 29.3 out of 100. However, a significant knowledge gap was observed, with 53% of respondents being unaware of the common sites for HPV-OPSCC and 63.8% being uninformed of the appropriate age for HPV vaccination. Females and those with a prior history of sexually transmitted diseases (STDs) had considerably higher levels of HPV vaccination knowledge (p < 0.05). The participants showed a favorable attitude towards their responsibility of informing patients about HPV-OPSCC and advocating HPV immunization. (4) Conclusions: This study underscores the need to enhance dental students' understanding of HPV-OPSCC and HPV immunization, enabling them to effectively engage in primary and secondary preventative efforts against HPV-OPSCC.

Inducing Long Lasting B cell and T cell Immunity against Multiple Variants of SARS-CoV-2 through Mutant Bacteriophage Qß - Receptor Binding Domain Conjugate.

More than three years into the global pandemic, SARS-CoV-2 remains a significant threat to public health. Immunities acquired from infection or current vaccines fail to provide long term protection against subsequent infections, mainly due to their fast-waning nature and the emergence of variants of concerns (VOCs) such as Omicron. To overcome these limitations, SARS-CoV-2 Spike protein receptor binding domain (RBD)-based epitopes were investigated as conjugates with a powerful carrier, the mutant bacteriophage Qß (mQß). The epitope design was critical to eliciting potent antibody responses with the full length RBD being superior to peptide and glycopeptide antigens. The full length RBD conjugated with mQß activated both humoral and cellular immune systems in vivo, inducing broad spectrum, persistent and comprehensive immune responses effective against multiple VOCs including Delta and Omicron variants, rendering it a promising vaccine candidate. This article is protected by copyright. All rights reserved.

Cost-effectiveness Analysis of Maternal Immunization with RSVpreF Vaccine for the Prevention of Respiratory Syncytial Virus Among Infants in Spain.

INTRODUCTION: Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections (ALRI) in children under one year of age. In high-income countries, RSV infections cause a significant overload of care every winter, imposing a significant burden to the healthcare system, which has made the development of prevention strategies a major global health priority. In this context, a new bivalent RSV prefusion F protein-based vaccine (RSVpreF) has recently been approved. The objective of this study was to evaluate the cost-effectiveness of vaccinating pregnant women with the RSVpreF vaccine to prevent RSV in infants from the Spanish National Healthcare System (NHS) perspective. METHODS: A hypothetical cohort framework and a Markov-type process were used to estimate clinical outcomes, costs, quality-adjusted life years (QALY) and cost-per-QALY gained (willingness-to-pay threshold: €25,000/QALY) for newborn infants born to RSV-vaccinated versus unvaccinated mothers over an RSV season. The base case analysis was performed from the NHS perspective including direct costs (€2023) and applying a discount of 3% to future costs and outcomes. To evaluate the robustness of the model, several scenarios, and deterministic and probabilistic analyses were carried out. All the parameters and assumptions were validated by a panel of experts. RESULTS: The results of the study showed that year-round maternal vaccination program with 70% coverage is a dominant option compared to no intervention, resulting in direct cost savings of €1.8 million each year, with an increase of 551 QALYs. Maternal vaccination could prevent 38% of hospital admissions, 23% of emergency room visits, 19% of primary care visits, and 34% of deaths due to RSV. All scenario analyses showed consistent results, and according to the probabilistic sensitivity analysis (PSA), the probability of maternal vaccination being cost-effective versus no intervention was 99%. CONCLUSIONS: From the Spanish NHS perspective, maternal vaccination with bivalent RSVpreF is a dominant alternative compared with a non-prevention strategy.

Cost-effectiveness of PCV20 to Prevent Pneumococcal Disease in the Pediatric Population: A German Societal Perspective Analysis.

INTRODUCTION: Since 2009, a pneumococcal conjugate vaccine (PCV) covering 13 serotypes (PCV13) has been included by Germany's Standing Committee on Vaccinations for infants, resulting in major reductions in pneumococcal disease (PD). Higher-valent vaccines may further reduce PD burden. This cost-effectiveness analysis compared 20-valent PCV (PCV20) under a 3+1 schedule with 15-valent PCV (PCV15) and PCV13, both under 2+1 schedule, in Germany's pediatric population. METHODS: A Markov model with annual cycles over a 10-year time horizon was adapted to simulate the clinical and economic impact of pediatric vaccination with PCV20 versus lower-valent PCVs in Germany. The model used PCV13 clinical effectiveness and impact studies as well as PCV7 efficacy studies for vaccine direct and indirect effect estimates. Epidemiologic, utility, and medical cost inputs were obtained from published sources. Benefits and costs were discounted at 3% from a German societal perspective. Outcomes included PD cases, deaths, costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs). RESULTS: In the base case, PCV20 provided greater health benefits than PCV13, averting more cases of invasive pneumococcal disease (IPD; 15,301), hospitalized and non-hospitalized pneumonia (460,197 and 472,365, respectively), otitis media (531,634), and 59,265 deaths over 10 years. This resulted in 904,854 additional QALYs and a total cost saving of €2,393,263,611, making PCV20 a dominant strategy compared with PCV13. Compared to PCV15, PCV20 was estimated to avert an additional 11,334 IPD, 704,948 pneumonia, and 441,643 otitis media cases, as well as 41,596 deaths. PCV20 was associated with a higher QALY gain and lower cost (i.e., dominance) compared with PCV15. The robustness of the results was confirmed through scenario analyses as well as deterministic and probabilistic sensitivity analyses. CONCLUSION: PCV20 3+1 dominated both PCV13 2+1 and PCV15 2+1 over 10 years. Replacing lower-valent PCVs with PCV20 would result in greater clinical and economic benefits, given PCV20's broader serotype coverage.

Pneumococcal diseases (e.g., ear infections, pneumonia, bloodstream infections) are among the leading causes of illness and death in children worldwide. The pneumococcal conjugate vaccine protects against pneumococcal diseases and has significantly reduced the number of newly diagnosed cases. Higher-valent vaccines (which provide coverage for a greater number of disease-causing serotypes) have recently received European Commission approval for use in adults and  children. This study examined costs and health benefits associated with the 20-valent pneumococcal conjugate vaccine (PCV20) under a 3+1 (i.e., three primary doses and one booster dose) schedule in Germany's childhood vaccination program compared with 13-valent pneumococcal conjugate vaccine (PCV13) and the 15-valent pneumococcal conjugate vaccine (PCV15), both under a 2+1 (two primary doses, one booster) schedule. PCV20 was estimated to result in greater health benefits from avoiding more cases in pneumococcal diseases and lower costs compared with both PCV13 and PCV15. PCV20, therefore, is considered the best option among the three vaccines for children in Germany.

Comparison of the Sensitivity and Specificity of Commercial Anti-Dengue Virus IgG Tests to Identify Persons Eligible for Dengue Vaccination.

The Advisory Committee on Immunization Practices (ACIP) recommended that dengue pre-vaccination screening tests for Dengvaxia administration have at least 98% specificity and 75% sensitivity. This study evaluates the performance of commercial anti-DENV IgG tests to identify tests that could be used for pre-vaccination screening. First, for 7 tests, we evaluated sensitivity and specificity in early convalescent dengue virus (DENV) infection, using 44 samples collected 7-30 days after symptom onset and confirmed by RT-PCR. Next, for the 5 best performing tests and two additional tests (with and without an external test reader) that became available later, we evaluated performance to detect past dengue infection among a panel of 44 specimens collected in 2018-2019 from healthy 9-16-year-old children from Puerto Rico. Finally, a full-scale evaluation was done with the 4 best performing tests using 400 specimens from the same population. We used virus focus reduction neutralization test and an in-house DENV IgG ELISA as reference standards. Of seven tests, five showed ≥75% sensitivity detecting anti-DENV IgG in early convalescent specimens with low cross-reactivity to Zika virus. For the detection of previous DENV infections the tests with the highest performance were the Euroimmun NS1 IgG ELISA (sensitivity 84.5%, specificity 97.1%) and CTK Dengue IgG rapid test R0065C with the test reader (sensitivity 76.2% specificity 98.1%). There are IgG tests available that can be used to accurately classify individuals with previous DENV infection as eligible for dengue vaccination to support safe vaccine implementation.

Safety and Efficacy of the Modified Vaccinia Ankara-Bavaria Nordic Vaccine Against Mpox in the Real World: Systematic Review and Meta-Analysis.

In May 2022, mpox began to spread worldwide, posing a serious threat to human public health. Modified Vaccinia Ankara-Bavaria Nordic (MVA-BN) is a live attenuated orthopoxvirus vaccine that has been authorized by the U.S. Food and Drug Administration as the vaccine of choice for the prevention of mpox. In this study, we conducted a meta-analysis of all currently published literature on the efficacy and safety of the MVA-BN vaccine in the real world, showing that the MVA-BN vaccine is effective and safe, with efficacy of up to 75% with a single dose and up to 80% with a two-dose vaccine. Meanwhile, we found that subcutaneous injection has lower local and systemic adverse events than intradermal injection, regardless of single- or two-dose vaccination, and subcutaneous injection is better tolerated in children, the elderly, or people with underlying medical conditions. These results have important reference value for clinical practice.

Genetic polymorphism and evidence of signatures of selection in the Plasmodium falciparum circumsporozoite protein gene in Tanzanian regions with different malaria endemicity.

BACKGROUND: In 2021 and 2023, the World Health Organization approved RTS,S/AS01 and R21/Matrix M malaria vaccines, respectively, for routine immunization of children in African countries with moderate to high transmission. These vaccines are made of Plasmodium falciparum circumsporozoite protein (PfCSP), but polymorphisms in the gene raise concerns regarding strain-specific responses and the long-term efficacy of these vaccines. This study assessed the Pfcsp genetic diversity, population structure and signatures of selection among parasites from areas of different malaria transmission intensities in Mainland Tanzania, to generate baseline data before the introduction of the malaria vaccines in the country. METHODS: The analysis involved 589 whole genome sequences generated by and as part of the MalariaGEN Community Project. The samples were collected between 2013 and January 2015 from five regions of Mainland Tanzania: Morogoro and Tanga (Muheza) (moderate transmission areas), and Kagera (Muleba), Lindi (Nachingwea), and Kigoma (Ujiji) (high transmission areas). Wright's inbreeding coefficient (Fws), Wright's fixation index (FST), principal component analysis, nucleotide diversity, and Tajima's D were used to assess within-host parasite diversity, population structure and natural selection. RESULTS: Based on Fws (< 0.95), there was high polyclonality (ranging from 69.23% in Nachingwea to 56.9% in Muheza). No population structure was detected in the Pfcsp gene in the five regions (mean FST = 0.0068). The average nucleotide diversity (π), nucleotide differentiation (K) and haplotype diversity (Hd) in the five regions were 4.19, 0.973 and 0.0035, respectively. The C-terminal region of Pfcsp showed high nucleotide diversity at Th2R and Th3R regions. Positive values for the Tajima's D were observed in the Th2R and Th3R regions consistent with balancing selection. The Pfcsp C-terminal sequences revealed 50 different haplotypes (H_1 to H_50), with only 2% of sequences matching the 3D7 strain haplotype (H_50). Conversely, with the NF54 strain, the Pfcsp C-terminal sequences revealed 49 different haplotypes (H_1 to H_49), with only 0.4% of the sequences matching the NF54 strain (Hap_49). CONCLUSIONS: The findings demonstrate high diversity of the Pfcsp gene with limited population differentiation. The Pfcsp gene showed positive Tajima's D values, consistent with balancing selection for variants within Th2R and Th3R regions. The study observed differences between the intended haplotypes incorporated into the design of RTS,S and R21 vaccines and those present in natural parasite populations. Therefore, additional research is warranted, incorporating other regions and more recent data to comprehensively assess trends in genetic diversity within this important gene. Such insights will inform the choice of alleles to be included in the future vaccines.