BACKGROUND: Influenza vaccines prevent influenza-related morbidity and mortality; however, suboptimal vaccine effectiveness (VE) of non-adjuvanted trivalent inactivated influenza vaccine (naTIV) or quadrivalent formulations in older adults prompted the use of enhanced products such as adjuvanted TIV (aTIV). Here, the VE of aTIV is compared to naTIV for preventing influenza-associated hospitalization among older adults. METHODS: A test-negative design study was used with pooled data from the 2012 to 2015 influenza seasons. An inverse probability of treatment (IPT)-weighted logistic regression estimated the Odds Ratio (OR) for laboratory-confirmed influenza-associated hospitalization. VE was calculated as (1-OR)*100% with accompanying 95% confidence intervals (CI). RESULTS: Of 7,101 adults aged ≥ 65, 3,364 received naTIV and 526 received aTIV. The overall VE against influenza hospitalization was 45.9% (95% CI: 40.2%-51.1%) for naTIV and 53.5% (42.8%-62.3%) for aTIV. No statistically significant differences in VE were found between aTIV and naTIV by age group or influenza season, though a trend favoring aTIV over naTIV was noted. Frailty may have impacted VE in aTIV recipients compared to those receiving naTIV, according to an exploratory analysis; VE adjusted by frailty was 59.1% (49.6%-66.8%) for aTIV and 44.8% (39.1%-50.0%) for naTIV. The overall relative VE of aTIV to naTIV against laboratory-confirmed influenza hospital admission was 25% (OR 0.75; 0.61-0.92), demonstrating statistically significant benefit favoring aTIV. CONCLUSIONS: Adjusting for frailty, aTIV showed statistically significantly better protection than naTIV against influenza-associated hospitalizations in older adults. In future studies, it is important to consider frailty as a significant confounder of VE.

OBJECTIVES: Older adults face increased risks from infectious diseases which are often preventable with vaccines. The current study examines demographic variation in vaccine hesitancy among older adults in North Dakota. METHODS: A mailed survey assessing age, gender, years of education, self-rated health, rurality, and political leaning as well as vaccine attitudes and vaccine acceptance was conducted with 739 older adults (65+), oversampled from rural counties. RESULTS: Vaccine hesitant attitudes were significantly higher among rural and politically-conservative older adults; whereas, vaccine acceptance was significantly higher among older, healthier, and politically-liberal older adults. Vaccine attitudes were significantly associated with vaccine acceptance and mediated the association between political leaning and vaccine acceptance. DISCUSSION: These findings highlight the demographic characteristics predictive of older adults' vaccine attitudes and acceptance. By better understanding the nuanced factors leading to hesitation to be vaccinated, practitioners can develop strategies to increase vaccination rates among this at-risk population.

BACKGROUND: New prevention strategies for respiratory syncytial virus (RSV) are emerging, but it is unclear if they will be cost-effective in low- and middle-income countries. We evaluated the potential impact and cost-effectiveness of two strategies to prevent RSV disease in young children in Vietnam. METHODS: We used a static cohort model with a finely disaggregated age structure (weeks of age <5 years) to calculate the RSV disease burden in Vietnam, with and without a single dose of maternal vaccine (RSVpreF, Pfizer) or of monoclonal antibody (Nirsevimab, Sanofi, Astra Zeneca). Each strategy was compared to no pharmaceutical intervention, and to each other. We assumed both strategies would be administered year round over a ten-year period. The primary outcome measure was the cost per disability-adjusted life year (DALY) averted, from a societal perspective. We ran probabilistic and deterministic uncertainty analyses. RESULTS: With central input assumptions for RSVpreF vaccine ($25/dose, 69 % efficacy, 6 months protection) and Nirsevimab ($25/dose, 77 % efficacy, 5 months protection), both options had similar cost-effectiveness ($3442 versus $3367 per DALY averted) when compared separately to no pharmaceutical intervention. RSVpreF vaccine had a lower net cost than Nirsevimab (net discounted cost of $213 m versus $264 m) but prevented fewer RSV deaths (24 % versus 31 %). Our results were very sensitive to assumptions about the dose price, efficacy, and duration of protection. At $5/dose and a willingness-to-pay threshold of 0.5 times the national GDP per capita, both prevention strategies are cost-effective. CONCLUSIONS: RSVpreF vaccine and Nirsevimab may be cost-effective in Vietnam if appropriately priced.

In a phase 2 safety and immunogenicity study of a chikungunya virus virus-like particle (CHIKV VLP) vaccine in an endemic region, of 400 total participants, 78 were found to be focus reduction neutralizing antibody seropositive at vaccination despite being ELISA seronegative at screening, of which 39 received vaccine. This post hoc analysis compared safety and immunogenicity of CHIKV VLP vaccine in seropositive (n = 39) versus seronegative (n = 155) vaccine recipients for 72 weeks post-vaccination. There were no differences in solicited adverse events, except injection site swelling in 10.3% of seropositive versus 0.6% of seronegative recipients (p = 0.006). Baseline seropositive vaccine recipients had stronger post-vaccination luciferase neutralizing antibody responses versus seronegative recipients (peak geometric mean titer of 3594 and 1728, respectively) persisting for 72 weeks, with geometric mean fold increases of 3.1 and 13.2, respectively. In this small study, CHIKV VLP vaccine was well-tolerated and immunogenic in individuals with pre-existing immunity. ClinicalTrials.gov Identifier: NCT02562482.

Mpox has affected many communities in the United States (U.S.), including people experiencing homelessness (PEH). Mpox vaccination has been an important tool to disrupt transmission and protect communities at risk of infection. To better understand mpox vaccine knowledge and attitudes, we surveyed 273 PEH and people accessing homeless service sites in San Francisco. Among 64 participants previously offered mpox vaccination, 38 (59 %) had received the vaccine. Among 209 participants not previously offered mpox vaccination, 108 (52 %) reported they would receive the vaccine. Vaccine acceptance was higher among transgender female participants and among male participants who reported male sex partner preference (MSM). Half of participants who declined vaccination identified that perception of personal risk and vaccine education may increase their likelihood of receiving an mpox vaccine. Leveraging trusted information sources to provide risk communication and vaccine education may increase vaccine uptake among PEH.

After the temporary end of COVID-19 in China in February 2023, the influenza epidemic peaked in March across many Chinese places. We recruited a total of 258 all-age subjects presenting influenza-like illness (ILI) in Shihezi city, China from January 1 to March 16, 2023, and tested for influenza virus infection. Using a test-negative design, we assessed influenza vaccine effectiveness (VE) of 56.3% (95% CrI: 13.6, 73.6) against medically attended, influenza illness during the delayed 2022/23 influenza epidemic. The findings contributed to the continuous monitoring of the influenza vaccine performance across the world, especially in the "post-COVID" pandemic era.

Some vaccines have a small risk of Guillain-Barré Syndrome (GBS), a rare autoimmune disorder characterized by paralysis if untreated. The CDC's Advisory Committee on Immunization Practices (ACIP) guidelines do not consider GBS a precaution for future vaccines unless GBS developed within six weeks after a tetanus-toxoid-containing vaccine or influenza vaccine. Our goal was to describe vaccine patterns before and after GBS diagnosis. We matched each of 709 patients diagnosed with GBS from 2002 to 2020 with Medicare supplemental insurance to 10 counterparts without GBS (1:10) on age and sex. Propensity score-based weighting balanced covariates between groups, and we estimated weighted mean cumulative counts (wMCC) of vaccines/person before and after GBS diagnosis. Among patients with GBS, 7% were diagnosed within 42 days after a vaccine. Prior to GBS diagnosis, the wMCC of vaccines per person was similar between GBS cases and matched counterparts, but after two years of follow-up, GBS patients received 21 fewer vaccines/100 people than counterparts (wMCC difference -0.21 vaccines/person, 95% CI -0.24 to -0.18); GBS patients received 16 vaccines/100 people while matched counterparts received 36/100. Vaccine use was reduced following GBS diagnosis despite no ACIP precaution for most (93%) patients in this study. The observed drop in vaccines after GBS diagnosis indicates a disconnect between clinical practice and current recommendations.

BACKGROUND: From 2008 to 2019, France has experienced a resurgence of measles epidemics. Surveillance data have shown that the proportion of cases vaccinated with two doses of measles-containing vaccine (MCV) increased with age, raising concerns about the duration of vaccine protection. Our objectives were to investigate age-stratified vaccine effectiveness (VE) for the second dose of MCV (MCV2) and to quantify protection levels over time. METHODS: We analyzed data on measles cases aged 2-31 years, reported via mandatory notification to the French measles surveillance system from October 2017 to September 2019. We estimated an age-stratified VE for MCV2 using the screening method, which compares the vaccination status of cases with that of the general population. We improved this method by accounting for natural immunity, exploring four scenarios with four possible levels of natural immunity in the population. In addition, we quantified the decay rate of protection over time, by fitting an exponential decay model among individuals vaccinated in early life. RESULTS: In the baseline analysis (absence of natural immunity), VE estimates were high in all age groups and decreased with age, from 99.6 % (95 % confidence interval: 99.3-99.8) in 2-5 years old to 91.4 % (85.1-95.0) in 26-31 years old. Accounting for natural immunity increased VE in the older age group to 93.2-99.2 % depending on the scenario. We estimated that VE was slowly decreasing over time, with an exponential decay rate of 0.0022/year (0.0017-0.0028), leading to VE of 96.7 % (96.0-97.4) 16 years after MCV2 vaccination. This decline was most compatible with scenario 2, a scenario of 4.4 % naturally immunized, non-vaccinated individuals in the 26-31 years old. CONCLUSION: Our study confirms the continued high effectiveness of two doses of MCV with only slight degradation, decades after immunization. These findings support the importance of achieving a very high vaccination coverage with 2 doses of MCV.

Socially and medically vulnerable groups (e.g., people 65 years or older, minoritized racial groups, non-telework essential workers, and people with comorbid conditions) experience barriers to COVID-19 prevention and treatment, increased burden of disease, and increased risk of death from COVID-19. Researchers are paying increased attention to social determinants of health (SDH) in explaining inequities in COVID-19-related health outcomes and rates of vaccine uptake. The purpose of the present manuscript is to identify clinically significant predictors of COVID-19 vaccine uptake among people who were socially and medically vulnerable to SARs-CoV-2 infection. Analysis was informed by the SDH framework and included a sample of 641 baseline surveys from participants in a clinical trial designed to increase COVID-19 testing. All participants were at high risk of developing COVID-19-related complications or dying from COVID-19. Following community-based participatory research principles, a well-established community collaborative board conducted every aspect of the study. Multiple logistic regressions were conducted to examine the relationships between individual and structural factors and COVID-19 vaccine uptake. In the final time adjusted model, we found that vaccine uptake was only predicted by specific individual-level factors: being 65 years and older, living with HIV/AIDS, and having previously received a flu vaccine or a COVID-19 test. Those reporting to believe in COVID-19-conspiracy theories were less likely to get the COVID-19 vaccine. More research is needed to identify predictors of vaccine uptake among people with comorbidities that make them more vulnerable to COVID-19 complications or death.

The U.S. Food and Drug Administration authorized use of mRNA COVID-19 bivalent booster vaccines on August 31, 2022. Currently, CDC's clinical guidance states that COVID-19 and other vaccines may be administered simultaneously. At time of authorization and recommendations, limited data existed describing simultaneous administration of COVID-19 bivalent booster and other vaccines. We describe simultaneous influenza and mRNA COVID-19 bivalent booster vaccine administration between August 31-December 31, 2022, among persons aged ≥6 months in the Vaccine Safety Datalink (VSD) by COVID-19 bivalent booster vaccine type, influenza vaccine type, age group, sex, and race and ethnicity. Of 2,301,876 persons who received a COVID-19 bivalent booster vaccine, 737,992 (32.1%) received simultaneous influenza vaccine, majority were female (53.1%), aged ≥18 years (91.4%), and non-Hispanic White (55.7%). These findings can inform future VSD studies on simultaneous influenza and COVID-19 bivalent booster vaccine safety and coverage, which may have implications for immunization service delivery.

The global distribution and ongoing evolution of type A swine influenza virus (IAV-S) continue to pose significant challenges against developing broadly protective vaccines to control swine influenza. This study focuses on the hemagglutinin (HA) consensus-based approach towards developing a more broadly protective swine influenza vaccine against various H3 strains circulating in domestic pig populations. By computationally analyzing >1000 swine H3 full-length HA sequences, we generated a consensus H3 and expressed it in the context of influenza A WSN/33 reverse genetics system. The derived recombinant chimeric swine influenza virus with the consensus H3 was inactivated and further evaluated as a potential universal vaccine in pigs. The consensus H3 vaccine elicited broadly active hemagglutination inhibition (HI) antibodies against divergent swine H3N2 influenza viruses including human H3N2 variant of concern, and strains belong to genetic clusters IV, IV-A, IV-B, IV-C, IV-D and IV-F. Importantly, vaccinated pigs were completely protected against challenge with a clinical swine H3N2 isolate in that neither viral shedding nor replication in lungs of vaccinated pigs were observed. These findings warrant further study of the consensus H3 vaccine platform for broad protection against diverse swine influenza viruses.

There is a major unmet need for strategies to improve the immunogenicity of vaccines to protect against highly pathogenic avian influenza strains with pandemic potential. This study tested the ability of adjuvants based on delta inulin (Advax™) alone or combined with a TLR9 agonist (Advax-CpG™) to enhance the immunogenicity of recombinant H5 hemagglutinin antigen expressed in insect cells (rH5HA) to protect mice against lethal influenza infection. The Advax-adjuvanted rH5HA induced high serum hemagglutination inhibition activity, as well as Th1 and Th2 cytokine secreting CD4 and CD8 T cells. Immunization protected mice against a lethal heterosubtypic H5N1 virus challenge. Mice immunized with an Advax-adjuvanted rHA2 stem antigen prepared by enzymatic cleavage of rH5HA produced serum antibodies devoid of hemagglutination inhibition activity, but these anti-HA2 antibodies were nevertheless able to transfer protection against lethal H1N1 or H3N2 infections to naïve mice. We hypothesize that the enhanced protection afforded by Advax-adjuvanted rH5HA may be mediated by the combination of neutralizing antibodies directed at the HA head, anti-HA2 stem antibodies plus memory CD4 + and CD8 + T cells. This outcome supports further development of the Advax-adjuvanted rH5 pandemic influenza vaccine platform.

BACKGROUND: Active surveillance systems for monitoring vaccine safety among pregnant women address some of the limitations of a current passive surveillance approach utilized in low- and middle-income countries (LMIC). However, few active surveillance systems in LMIC exist. Our study assessed the feasibility of utilizing three existing data collection systems in Kenya for active surveillance of maternal immunization and to assess the applicability of Global Alignment of Immunization Safety Assessment in pregnancy (GAIA) case definitions that were initially developed for clinical trials within these systems. METHODS: We assessed applicability of GAIA case definition for maternal Tetanus Toxoid exposure, stillbirth, low birth weight, small for gestational age, Neonatal Invasive Blood Stream Infection (NIBSI), prematurity and neonatal death in two routine web-based health information systems (Kenya EMR and DHIS-2), and a web-based population-based pregnancy research platform (ANCOV1) in Kenya. RESULTS: All three HIS were capable of reporting selected outcomes to varying degrees of GAIA certainty. The ANCOV platform was the most robust in collecting and collating clinical data for effective maternal pharmacovigilance. The utilization of facility- and district-aggregated data limits the usefulness of DHIS-2 in pharmacovigilance as currently operationalized. While the Kenya EMR contained individual level data and meets the key considerations for effective pharmacovigilance, it was used primarily for HIV care and treatment records in a small proportion of health facilities and would require additional resources to expand to all antenatal care facilities and to link maternal and infant records. DISCUSSION: Population-based research studies may offer a responsive short-term option for implementing maternal vaccine pharmacovigilance in LMICs. However, the foundation exists for long-term capacity building within the national health electronic data systems to provide this critical service as well as ensure participation of the country in international studies on maternal vaccine safety.

Despite Brazil's tradition of successful mass immunization programs, the country has been experiencing alarming declines in vaccination coverage, especially among children. That is aggravated by the growth of anti-vaccine movements and the spread of health misinformation in social media in the last decade, which have worsened during the COVID-19 outbreak. Several reports link populism and far-right politicians to anti-vaccination support worldwide, which was also the case in Brazil during president Jair Bolsonaro's administration. This project aimed to identify the circulating pro and anti-vaccine narratives in Portuguese on Twitter, during a crucial decision-making period regarding childhood vaccination in Brazil, from December 9, 2021, until February 9, 2022. From the over one million tweets and four million retweets collected, we identified two well-defined groups, one in favor and another against vaccination. Within the sample, we selected 1500 influencer tweets with the highest impact (>500 retweets) and conducted content analysis. Although the pro-vaccine influencers were more retweeted than anti-vaxxer ones, we observed that anti-vaccine movements were more succesful in framing discussions on Twitter. The subject of COVID-19 was the target of political polarization embedded in populist, anti-science and anti-traditional media discourses promoted by anti-vaxxers. As a counterpart, the pro-vaccine influencers reacted inarticulately, focusing on criticizing the anti-vaccination actors, attitudes, and policies instead of promoting vaccines. Based on reults, we claim that a well-coordinated network of health communicators from science centers and health institutions, in partnership with properly briefed social media influencers and fact-checking sources, would more efectively pre-tempt the public about vaccine misinformation.

INTRODUCTION: Vaccine surveillance for children in England focuses on coverage at ages 1, 2, and 5 years. Previous studies exploring vaccine timeliness have used different arbitrary categories to define whether vaccines were received 'late' or 'on time'. This paper aims to provide more detailed and holistic information on timing and patterns of vaccine uptake across the childhood immunisation schedule in England. METHODS: We included all children born in England between 2006 and 2014 and registered in the Clinical Practice Research Datalink (CPRD) Aurum, a primary care electronic health record. We described vaccine uptake for representative antigens (pertussis, pneumococcus, measles) by age in days and stratified by ethnicity, region and birth cohort. Alluvial diagrams were used to illustrate common journeys through the vaccination schedule, and we applied survival analysis using accelerated failure time models (AFT) to predict age of vaccine receipt based on timing of previous doses. RESULTS: 573,015 children were followed up until their fifth birthday, when they had 90.16 % coverage for two doses of measles, mumps, rubella (MMR) vaccine and 88.78% coverage for four doses of diphtheria, tetanus, pertussis (DTP) vaccine. Overall, the later the age at which a vaccine was due, the more delay in vaccination. Children of Black Ethnicity or from London showed deviating uptake patterns. If a child received their third DTP dose more than a year later than recommended, they would receive the next dose 2.7 times later than a child who was vaccinated on time. A smaller delay was found for children who did not receive first MMR dose on time. DISCUSSION: We showed that the risk of vaccination delay increased with the age of the child and significant delay of previous doses. Primary care data can help to promptly identify children at higher risk of delayed vaccination.

As the COVID19 pandemic progresses, there is an increasing need to evaluate the performance of vaccine strategies. This study investigated the vaccine schedule performance of heterologous vaccination compared to homologous vaccination in preventing Omicron SARS-CoV2 infection in the adult population. This retrospective cohort study utilized data from the Infections Regional Information System and the Apulia Regional Vaccine Registry to identify individuals who received a booster dose of one of 14 different COVID19 vaccination schedules between September 2021 and August 2022 in the province of Lecce, Southern Italy. The standardized cumulative incidence of SARS-CoV2 infection after the booster dose was assessed and the risk of infection between subgroups of heterologous and homologous vaccination schedules was compared using the Cochran-Mantel-Haenszel test. A total of 469,069 subjects were included in the study. The standardized incidence of SARS-CoV2 infection varied greatly among different vaccine schedules, with the highest and lowest being AZ-AZ-BNT (34.7 %) and MOD-MOD-BNT (18.9 %), respectively, and some heterologous schedules performing better than homologous ones. The risk of SARS-CoV2 infection was significantly lower in individuals who received specific heterologous vaccination schedules compared to homologous vaccination schedules, the best performing being MOD-MOD-BNT with a common odd ratio of 0.661 (IC. 95 % [0.620-0.704]). This study provides evidence that heterologous vaccination schedules may be more effective in preventing Omicron SARS-CoV2 infection compared to homologous vaccination schedules, highlighting how the vaccine product, rather than the platform, is involved in the different protection provided by heterologous vaccination.

The Healthy People 2030 goal is for 80% of all adolescents to complete their HPV vaccination series. Per the 2021, National Immunization Survey-Teen (NIS-Teen), 61.7% of adolescents have completed the series, and Indiana lags below the national average (55.2%). The present study estimated the 2-dose HPV vaccine series completion rates across Indiana counties among individuals aged 9-14 years who received their first dose of vaccine and determined what factors were associated with series completion at the county level. The association of county-level sociodemographic and health measures with series completion was also examined. Data were extracted from the Indiana Immunization Information System (IIS), administered by the Indiana Department of Health. All vaccine providers are required to report all immunizations to the system for any patient under age 19 years. All Indiana children ages 9-14 years at the time of first dose who had initiated HPV vaccination in 2017 or 2018 were included. Two-dose series completion was evaluated through October of 2020, allowing a minimum gap of 22 months from first dose administration. All statistical analyses were conducted at the county-level. The Indiana HPV vaccination series completion rate among individuals that received the first dose was on average 73% across counties, ranging from 55.7% to 90.4%. Higher series completion was positively associated with primary care providers per capita, participation in mammography screening among Medicare enrollees, median household income, life expectancy, percentage of residents with some college, percentage of adults up-to-date with colonoscopy screening, and percentage of adults with flu vaccine. There was wide variability in series completion across Indiana counties. HPV series completion was associated with county-level sociodemographic and health measures, particularly variables reflecting difficulties with access to care and lack of financial resources.

Porcine Reproductive and Respiratory Syndrome (PRRS) is an important viral disease of swine that causes significant mortality in piglets and production losses in adult pigs. In this study, we investigated the protective efficacy of an inactivated PRRS virus vaccine candidate and evaluated the differences in PRRSV specific anamnestic response in piglets when challenged with live PRRSV at two different intervals post-immunization. Six-week-old piglets were immunized intramuscularly with an inactivated, Montanide ISA-206 adjuvanted Indian PRRSV isolate, followed by a booster dose at 21 days post-immunization. Homologous live PRRS virus challenge was done on 60 and 180 days post-booster (dpb). We assessed humoral and cell-mediated immune responses at various intervals post-immunization and after challenge. Viraemia, virus shedding in nasal secretions and lung lesion scores were studied to assess the efficacy of the vaccine candidate. All the immunized pigs developed PRRSV-specific antibodies upon booster dose administration. Neutralizing antibody (NA) titres before challenge, in most animals, ranged between 0 and 4. Potentially protective NA titre of 8 was observed in serum of seven out of the 12 immunized piglets after challenge, across the immunized groups. A significant increase in the mean T-helper, T-cytotoxic, memory or activated T-helper and NK cell populations was observed in immunized piglets challenged at 180 dpb, from 4 to 11 dpc, 5 to 11 dpc, 5 to 7 dpc and 6 to 11 dpc, respectively as compared to the challenge controls. Protective efficacy of the inactivated PRRSV antigen against the homologous virus challenge was evidenced by earlier onset of PRRSV specific virus neutralizing antibodies and cell mediated immune responses, reduced viremia, nasal virus shedding and severity of lung lesions in immunized piglets as compared to unimmunized controls post-challenge. Our results indicated that the inactivated PRRSV antigen elicited better virus specific anamnestic immune responses in piglets when challenged at six months after the single booster dose, due to age related increase in antigen-specific memory T helper cell responses, as compared to those challenged at 2 months post booster.

INTRODUCTION: The struggle against influenza, and more recently against Coronavirus Disease 2019 (COVID-19), relies mostly on protective measures and vaccines. In France, COVID-19 vaccination campaigns include children over 5 years of age, whereas the influenza vaccine is reserved for children and infants older than 6 months with severe chronic disease. The final decision to vaccinate ultimately rests with the parents. This study aimed to explore the opinions of parents regarding COVID-19 and influenza vaccinations, and which factors are likely to influence their decision in order to improve prevention approaches, and thus obtain better vaccination coverage among children. METHODS AND SURVEY: In this trans-sectional multicenter survey, self-administered questionnaires were sent to parents of children attending 14 childcare institutions over a period of 2 months, December 2021-February 2022. The questionnaire consisted of three sections: the first collected general, social and professional data, the second addressed perceived parental acceptability regarding influenza and COVID-19 vaccinations in healthy children, while the last section explored the main sources of information consulted by the parents regarding vaccinations. Subject's characteristics were described using number and percentages, as they are all categorical variables. Description of answers regarding both influenza and COVID-19 sources of information data were performed. Characteristics of patients answers were described and compared according to intention of vaccine groups. RESULTS: Among the 343 questionnaires collected, 41.7 % of respondents stated they were supportive of vaccination of their children against influenza and 37 % against COVID-19. Media (Internet, TV and radio) were the most cited sources of information. Incentive factors for both vaccination against influenza and COVID-19 were individual, and collective protection. Limiting factors were fear of side effect and Age of the child. Media was the sole source of information, concerning vaccination against influenza for 59 % non-graduates and 28 % of participants having a higher education level, and respectively 49 % and 19 % for vaccination against COVID-19. The acceptability rate was influenced by the level of education and the sources of information. DISCUSSION AND CONCLUSION: About 40 % of the parents were supportive of children's vaccinations against COVID-19 and influenza respectively (37 % and 42 %) in order to protect the vulnerable people around them. The media influences the decision to vaccinate especially when the level of education is low.

INTRODUCTION: Timeliness of routine vaccination shapes childhood infection risk and thus is an important public health metric. Estimates of indicators of the timeliness of vaccination are usually produced at the national or regional level, which may conceal epidemiologically relevant local heterogeneities and makeitdifficultto identify pockets of vulnerabilities that could benefit from targeted interventions. Here, we demonstrate the utility of geospatial modelling techniques in generating high-resolution maps of the prevalence of delayed childhood vaccination in The Gambia. To guide local immunisation policy and prioritize key interventions, we also identified the districts with a combination of high estimated prevalence and a significant population of affected infants. METHODS: We used the birth dose of the hepatitis-B vaccine (HepB0), third-dose of the pentavalent vaccine (PENTA3), and the first dose of measles-containing vaccine (MCV1) as examples to map delayed vaccination nationally at a resolution of 1 × 1-km2 pixel. We utilized cluster-level childhood vaccination data from The Gambia 2019-20 Demographic and Health Survey. We adopted a fully Bayesian geostatistical model incorporating publicly available geospatial covariates to aid predictive accuracy. The model was implemented using the integrated nested Laplace approximation-stochastic partial differential equation (INLA-SPDE) approach. RESULTS: We found significant subnational heterogeneity in delayed HepB0, PENTA3 and MCV1 vaccinations. Specificdistricts in the central and eastern regions of The Gambia consistentlyexhibited the highest prevalence of delayed vaccination, while the coastal districts showed alower prevalence forallthree vaccines. We also found that districts in the eastern, central, as well as in coastal parts of The Gambia had a combination of high estimated prevalence of delayed HepB0, PENTA3 and MCV1 and a significant population of affected infants. CONCLUSIONS: Our approach provides decision-makers with a valuable tool to better understand local patterns of untimely childhood vaccination and identify districts where strengthening vaccine delivery systems could have the greatest impact.