History Of Previous Vaccination Research Articles

Relative vaccine protection, disease severity, and symptoms associated with the SARS-CoV-2 omicron subvariant BA.2.86 and descendant JN.1 in Denmark: a nationwide observational study

During the 2023 Danish COVID-19 vaccination campaign, an updated monovalent mRNA vaccine targeting the SARS-CoV-2 omicron XBB.1.5 subvariant was administered. However, the rapid spread of a genetically divergent omicron BA.2.86 subvariant, JN.1, since September, 2023, poses potential challenges due to its rapid dominance and possible immune escape. Using national electronic health registry data from all regions of Denmark, we aimed to investigate whether the SARS-CoV-2 subvariant BA.2.86, and its descendant JN.1, differed from other circulating variants in terms of their ability to escape vaccine protection, the risk of infection leading to severe disease, and self-reported symptoms among infected people. In this observational study, we included all residents of Denmark aged 65 years and older who tested positive for SARS-CoV-2 by PCR between Oct 1 and Dec 31, 2023, and for whom genomic data on the SARS-CoV-2 variant that had caused their infection were available. Data from clinical testing, sentinel, and self-sampling-based surveillance were linked with national electronic civil, vaccination, and hospitalisation registers. The relative protection of the XBB.1.5 updated COVID-19 vaccine against BA.2.86 infections versus infections with other variants was analysed in a case-only study, and the relative risk of hospitalisation in people infected with BA.2.86 versus other variants was analysed in a case-control study. Both analyses were adjusted for time, comorbidities, and previous vaccination history, among other potential confounders. Additionally, prevalence patterns in self-reported symptoms among people of all ages infected with SARS-CoV-2 were reported separately by subvariant. Of the 7581 people in Denmark aged 65 years or older who tested positive for SARS-CoV-2 by PCR during the study period, 5882 (78%) samples were eligible for sequencing. 3862 (66%) of these passed quality control, were successfully sequenced, and the SARS-CoV-2 variant and subvariant identified, and these individuals were included in the study. Of these 3862 people, 2184 (57%) were infected with the BA.2.86 subvariant, including 1615 JN.1 infections. Participants infected with BA.2.86 had 1·52 (95% CI 1·25-1·86) times the odds, and those infected with JN.1 had 1·60 (1·27-2·02) times the odds, of having received the XBB.1.5 vaccine at least 7 days before their infection compared with participants infected with a non-BA.2.86 variant. The severity analysis showed no evidence of association between the infecting variant and the risk of COVID-19 hospitalisation (odds ratio 1·04 [95% CI 0·86-1·26] for BA.2.86 and 1·07 [0·85-1·34] for JN.1). Similarly, there was no evidence of differences in self-reported symptoms by variant strain. Compared with other SARS-CoV-2 variants, BA.2.86 and the JN.1 sublineage were less sensitive to vaccine-induced immune protection from the XBB.1.5 updated COVID-19 vaccine; however, we found no evidence that infection with BA.2.86 or JN.1 resulted in increased disease severity or different symptom profiles. Although less effective against the new variants, XBB.1.5 vaccination remains protective and reduces the risk of infection and COVID-19 disease. The Danish Government and the EU's EU4Health programme.

The effect of a financial incentive on COVID-19 vaccination uptake, and predictors of uptake, in people experiencing homelessness: A randomized controlled trial

People who are homeless are at increased risk of COVID-19 infection, and of poorer associated outcomes. Delivering vaccinations to, and ensuring uptake of multiple doses in, people who are homeless is complex. Financial incentives may improve vaccination uptake, particularly in people who have not received routine vaccinations previously, though evidence about the effect of incentives is limited and variable.This randomized controlled trial (ANZCTR 383156) assessed the effect of a financial incentive (an A$10 grocery voucher) on uptake of the second COVID-19 vaccination in Australian adults who were homeless, and who had received their first dose. Participants were recruited through a vaccination program for people experiencing homelessness between September 2021 and January 2022. They were followed-up for a minimum of 6.5 months. Uptake was measured ‘on-time’ at 6 weeks, and at any time during the trial period. Vaccination status was checked on the Australian Immunisation Register. Demographic and vaccination program characteristics associated with uptake were also investigated.Eighty-six people consented to participate, and 43 were randomly allocated to each of the ‘incentive’ and ‘no incentive’ groups. The incentive slightly increased the likelihood of a participant receiving a second vaccination on-time (risk difference (RD), 11.6 % [95 %CI, −9.0, 32.2 %]; p = 0.27), and at any time during the trial (RD, 14.0 % [95 %CI, –2.2, 30.1 %], p = 0.09). The incentive had a significant positive effect on uptake in people with no previous vaccination history, increasing their likelihood of receiving a second vaccination on-time (RD, 42.3 % [95 %CI, 15.7, 68.8 %]; p = 0.002) and at any time during the trial (RD, 38.7 % [95 %CI, 16.1, 61.3 %], p < 0.001).Financial incentives may increase COVID-19 vaccination uptake in people who are homeless, and particularly those who have no previous vaccination history. Future research should consider alternative incentive values, types, and cost-effectiveness.

Serological detection of Newcastle disease virus in backyard poultry production system in Woliso District South West Shewa, Central Ethiopia.

Newcastle disease (ND)is one of the most important respiratory viral diseases. The disease is endemic in many parts of Ethiopia. However, there is no clear record about the introduction of the virus to the country (Ethiopia). Hence, detail about the ND is very important in its (ND) control and prevention. Despite these facts, there is no available research work done on ND in the current research area that would help either as references for researchers or that could help in the control and prevention of the disease. Therefore, the objective of this study was to detect the ND virus (NDV), using serological methods in from December 2018 to November 2019. A cross-sectional type of study was conducted to detect the NDV. The convenience sampling method was used for sample data collection. Before data collection, chicken with previous history of vaccination against the NDV was excluded from the sampling animals. Then, a total of 348 blood samples of 2 mLwere collected from the brachial vein in 3 mLdisposable syringes. The serum was collected in labeled 2 mL cryovial tubes. Indirect enzyme-linked immunosorbent assay(ELISA) tests were performed to detect antibodies against NDV and to determine its antibody titer. The test was performed using (ID.vetinnovative version 2) procedure. In the indirect ELISA test, 37.64% (131/348) were positive and antibody titer mean value of (1761.9088) was scored. The standard deviation of 2592.42160 and a percentage coefficient of variation of147% was scored. From the finding, we conclude that indirect ELISA test detected the presence of the NDV in the study area and the heterogeneousity of antibody titer in the study area. Therefore, further molecular characterization and epidemiological investigation should be carried and vaccination of animals is critical in the study area.

The refusal of COVID-19 vaccination and its associated factors: a meta-analysis

Background To date, more than 10% of the global population is unvaccinated against the coronavirus disease 2019 (COVID-19), and the reasons why this population is not vaccinated are not well identified. Objectives We investigated the prevalence of COVID-19 vaccine refusal and to assess the factors associated with COVID-19 vaccine refusal. Methods A meta-analysis was conducted from August to November 2022 (PROSPERO: CRD42022384562). We searched for articles investigating the refusal of COVID-19 vaccination and its potential associated factors in PubMed, Scopus, and the Web of Sciences. The quality of the articles was assessed using the Newcastle–Ottawa scale, and data were collected using a pilot form. The cumulative prevalence of the refusal to vaccinate against COVID-19 was identified through a single-arm meta-analysis. Factors associated with COVID-19 vaccine refusals were determined using the Mantel-Haenszel method. Results A total of 24 articles were included in the analysis. Our findings showed that the global prevalence of COVID-19 vaccine refusal was 12%, with the highest prevalence observed in the general population and the lowest prevalence in the healthcare worker subgroup. Furthermore, individuals with a high socioeconomic status, history of previous vaccination, and a medical background had a lower rate of COVID-19 vaccination refusal. Subsequently, the following factors were associated with an increased risk of COVID-19 vaccine refusal: being female, educational attainment lower than an undergraduate degree, and living in a rural area. Conclusion Our study identified the prevalence of and factors associated with COVID-19 vaccine refusal. This study may serve as an initial reference to achieve global coverage of COVID-19 vaccination by influencing the population of COVID-19 vaccine refusal.

Efficacy of typhoid conjugate vaccine: final analysis of a 4-year, phase 3, randomised controlled trial in Malawian children

Randomised controlled trials of typhoid conjugate vaccines among children in Africa and Asia have shown high short-term efficacy. Data on the durability of protection beyond 2 years are sparse. We present the final analysis of a randomised controlled trial in Malawi, encompassing more than 4 years of follow-up, with the aim of investigating vaccine efficacy over time and by age group. In this phase 3, double-blind, randomised controlled efficacy trial in Blantyre, Malawi, healthy children aged 9 months to 12 years were randomly assigned (1:1) by an unmasked statistician to receive a single dose of Vi polysaccharide conjugated to tetanus toxoid vaccine (Vi-TT) or meningococcal capsular group A conjugate (MenA) vaccine. Children had to have no previous history of typhoid vaccination and reside in the study areas for inclusion and were recruited from government schools and health centres. Participants, their parents or guardians, and the study team were masked to vaccine allocation. Nurses administering vaccines were unmasked. We did surveillance for febrile illness from vaccination until follow-up completion. The primary outcome was first occurrence of blood culture-confirmed typhoid fever. Eligible children who were randomly assigned and vaccinated were included in the intention-to-treat analyses. This trial is registered at ClinicalTrials.gov, NCT03299426. Between Feb 21, 2018, and Sept 27, 2018, 28 130 children were vaccinated; 14 069 were assigned to receive Vi-TT and 14 061 to receive MenA. After a median follow-up of 4·3 years (IQR 4·2-4·5), 24 (39·7 cases per 100 000 person-years) children in the Vi-TT group and 110 (182·7 cases per 100 000 person-years) children in the MenA group were diagnosed with a first episode of blood culture-confirmed typhoid fever. In the intention-to-treat population, efficacy of Vi-TT was 78·3% (95% CI 66·3-86·1), and 163 (129-222) children needed to be vaccinated to prevent one case. Efficacies by age group were 70·6% (6·4-93·0) for children aged 9 months to 2 years; 79·6% (45·8-93·9) for children aged 2-4 years; and 79·3% (63·5-89·0) for children aged 5-12 years. A single dose of Vi-TT is durably efficacious for at least 4 years among children aged 9 months to 12 years and shows efficacy in all age groups, including children younger than 2 years. These results support current WHO recommendations in typhoid-endemic areas for mass campaigns among children aged 9 months to 15 years, followed by routine introduction in the first 2 years of life. Bill & Melinda Gates Foundation.

Vaccine Mandates and Influenza Vaccination During the Pandemic.

To determine whether a state influenza vaccine mandate and elevated community coronavirus disease 2019 (COVID-19) severity affected a child's probability of receiving an influenza vaccine during the 2020-2021 influenza season, given the child's previous vaccination history. Longitudinal cohort study using enrollment and claims data of 71 333 children aged 6 months to 18 years living in Massachusetts, New Hampshire, and Maine, from a regional insurer. Schoolchildren in Massachusetts were exposed to a new influenza vaccine mandate in the 2020-2021 season. Community COVID-19 severity was measured using county-level total cumulative confirmed case counts between March 2020 and August 2020 and linked by zip codes. The primary outcome of interest was a claim for any influenza vaccine in the 2020-2021 season. Children living in a state with a vaccine mandate during the 2020-2021 influenza season had a higher predicted probability of receiving an influenza vaccine than those living in states without a mandate (47.7%, confidence interval 46.4%-49.0%, vs 21.2%, confidence interval 18.8%-23.6%, respectively, for previous nonvaccinators, and 78.2%, confidence interval 77.4%-79.0%, vs 58.2%, confidence interval 54.7%-61.7%, for previous vaccinators); the difference was 6.5 percentage points greater among previous nonvaccinators (confidence interval 1.3%-11.7%). Previously vaccinated children had a lower predicted probability of receiving an influenza vaccine if they lived in a county with the highest COVID-19 severity compared with a county with low COVID-19 severity (72.1%, confidence interval 70.5%-73.7%, vs 77.3%, confidence interval 74.7%-79.9%). Strategies to improve uptake of influenza vaccination may have differential impact based on previous vaccination status and should account for community factors.

Immunogenicity and reactogenicity of yellow fever vaccine in people living with HIV.

To evaluate immunogenicity and reactogenicity of Yellow Fever (YF) vaccine in people living with HIV (PLWH) compared to HIV-uninfected controls. In this longitudinal interventional trial (NCT03132311), PLWH with CD4 ≥200 cells/μL and controls, aged 18-59, without a previous history of YF vaccination received a single standard dose of YF vaccine (17DD) and were followed at Days 5, 30 and Year 1. YF-neutralization titers were measured at Days 0, 30 and Year 1 and geometric mean titers (GMT) were calculated. Adverse events (AE) and YF virus detection were measured at Days 5 and 30. Linear regression evaluated factors associated with YF-neutralization titers. 218 PLWH and 82 controls were included. At baseline, all PLWH were using antiretroviral therapy; 92.6% had undetectable HIV viral load (VL) and median CD4 was 630 cells/μL (IQR 463-888). YF vaccine was safe and there were no serious AEs. At Day 30, seroconversion was observed in 98.6% of PLWH (95%CI: 95.6-99.6) and in 100% of controls (95%CI: 93.9-100); at Year 1, 94.0% of PLWH (95% CI: 89.6-96.7) and 98.4% of controls (95%CI 90.3-99.9) were seropositive. PLWH had lower GMTs than controls at Day 30 and Year 1. Baseline VL >1,000 copies/mL, low CD4 counts and low CD4/CD8 ratio were associated with lower YF-neutralization titers. YF vaccine is safe in PLWH with CD4 ≥ 200 cells/μL. YF vaccine immunogenicity is impaired in PLWH, particularly among those with high VL, low CD4 counts and low CD4/CD8 ratio at vaccination and YF-neutralization titers decays over time.

Acute COVID-19 in unvaccinated children without a history of previous infection during the delta and omicron periods

ABSTRACT Background The Omicron variant has been the predominant severe acute respiratory syndrome coronavirus 2 variant circulating in Korea since January 2022. This study evaluated and compared the clinical characteristics of children with coronavirus disease 2019 (COVID-19) between the Delta and Omicron periods. Methods The medical records of children aged < 12 years diagnosed with acute COVID-19 (<2 weeks of symptom onset) at seven university-affiliated hospitals were retrospectively reviewed. Children with a previous history of COVID-19 or vaccination were excluded. The clinical characteristics of the included children during the Delta (1 August 2021 to 15 January 2022) and Omicron (16 January to 30 June 2022) periods were compared. Results Among the 515 children included in the study, 36 (7.0%) and 479 (93.0%) were diagnosed with COVID-19 during the Delta and Omicron periods, respectively. A total of 142 (27.6%) were hospitalized, and the hospitalization rate was higher during the Delta period than the Omicron period (91.7% vs. 22.8%, p < 0.001). The incidence of fever (p = 0.009), vomiting (p = 0.031), and seizures (p = 0.007) was higher during the Omicron period, whereas the incidence of rhinorrhea (p = 0.027) was higher during the Delta period. Clinical severity and outcomes were comparable between the two periods. During the Omicron period, 6.4% of the hospitalized children received oxygen therapy and 1.8% received intensive care. Conclusion The incidence of fever and seizures was higher during the Omicron period in pediatric patients without a history of vaccination or previous COVID-19. However, the clinical severity was similar during both periods.

The community acceptance of COVID-19 vaccines in Rakhine State: A cross-sectional study in Myanmar.

The global pandemic situation of SARS-CoV-2 (COVID-19) has been ongoing for more than 2 years with the emergence of different variants. With the rapid development of vaccines, countries including Myanmar rolled out vaccination programs to reduce the morbidity and mortality due to COVID-19 with the ultimate goal to end the pandemic. This study seeks to explore the acceptance of the general adult population towards the COVID-19 vaccines administered by the Ministry of Health, and barriers to vaccine acceptance. A quantitative cross-sectional study was conducted by adopting valid and reliable questionnaires from similar studies around the world. Simple random sampling was used to select 288 participants from 12 townships of Rakhine State, Myanmar. The interview was performed using standardized paper-based documents. While the data entry and manipulation were performed using Microsoft Excel, the data analysis process was performed using the Statistical Package for Social Science (SPSS) software. As descriptive statistics, the level of vaccine acceptance, and barriers to vaccine acceptance were calculated. Chi-square analysis and bivariate logistics regression was performed to explore the associated socio-demographic characteristics, COVID-19 and vaccine-related experience, and perceptions of participants on the health belief model (HBM) domains related to vaccine acceptance. A total of 276 participants entered the study and revealed an overall vaccine acceptance level of 91.3%. Higher level of education, working in skilled manual and sales services, monthly income of more than 200,000 MMK (111 USD), history of previous vaccination, not experiencing side effects of vaccine after previous immunization, and elements of the health belief model (HBM) were associated with higher vaccine acceptance. The barriers to vaccine acceptance were mistrust of the efficacy of vaccines and potential major adverse events of COVID-19 vaccines. The high level of vaccine acceptance among the general population in Rakhine state provides an opportunity for health authorities to achieve high vaccination coverage within the community. Nevertheless, the vaccine-related education campaigns should be targeted and conveyed frequently to the sub-groups of the population with vaccine hesitancy to obtain the highest achievable level of vaccine coverage within the community for the ultimate goal to end the pandemic.

Are Saudi Healthcare Workers Willing to Receive the Monkeypox Virus Vaccine? Evidence from a Descriptive-Baseline Survey.

Since Saudi Arabia has already confirmed multiple monkeypox (Mpox) cases, it is essential to initiate timely preventive measures, including the implementation of vaccines. In this cross-sectional study, an online survey was conducted among healthcare workers (HCWs) in Saudi Arabia to understand their willingness to receive the Mpox vaccine. A structured questionnaire was used to gather the data. The study comprised 734 samples. Our study found that among study participants, 52.7% were willing to receive the Mpox vaccine and showed that sociodemographic factors were not significantly associated with vaccine willingness. Previous vaccination history (such as influenza and COVID-19) was significantly associated with Mpox vaccine willingness. The respondents reported that the main reasons for receiving the Mpox vaccine were their trust in the Saudi Health Ministry (57.7%) and their understanding that the vaccine was a social responsibility (44.6%). Furthermore, the majority of the respondents (74.7%) reported that they were motivated by the need to protect themselves, their family and their friends. Insufficient vaccine information and fear of unknown adverse reactions were the most reported reasons for an unwillingness to receive the Mpox vaccine. In conclusion, increasing Mpox vaccine-related awareness and focusing on greater information dissemination to reduce fear and increase vaccine uptake is highly recommended.

Health effects of routine measles vaccination and supplementary immunisation activities in 14 high-burden countries: a Dynamic Measles Immunization Calculation Engine (DynaMICE) modelling study

WHO recommends at least 95% population coverage with two doses of measles-containing vaccine (MCV). Most countries worldwide use routine services to offer a first dose of measles-containing vaccine (MCV1) and later, a second dose of measles-containing vaccine (MCV2). Many countries worldwide conduct supplementary immunisation activities (SIAs), offering vaccination to all people in a specific age range irrespective of previous vaccination history. We aimed to estimate the relative effects of each dose and delivery route in 14 countries with high measles burden. We used an age-structured compartmental dynamic model, the Dynamic Measles Immunization Calculation Engine (DynaMICE), to assess the effects of different vaccination strategies on measles susceptibility and burden during 2000-20 in 14 countries with high measles incidence (containing 53% of the global birth cohort and 78% of the global measles burden). Country-specific routine MCV1 and MCV2 coverage data during 1980-2020 were obtained from the WHO and UNICEF Estimates of National Immunization Coverage database for all modelled countries and SIA data were obtained from the WHO summary of measles and rubella SIAs. We estimated the incremental health effects of different vaccination strategies using prevented cases of measles and deaths from measles and their efficiency using the incremental number needed to vaccinate (NNV) to prevent an additional measles case. Compared with no vaccination, MCV1 implementation was estimated to have prevented 824 million cases of measles and 9·6 million deaths from measles, with a median NNV of 1·41 (IQR 1·35-1·44). Adding routine MCV2 to MCV1 was estimated to have prevented 108 million cases and 404 270 deaths, whereas adding SIAs to MCV1 was estimated to have prevented 256 million cases and 4·4 million deaths. Despite larger incremental effects, adding SIAs to MCV1 (median incremental NNV 6·02, 5·30-7·68) showed reduced efficiency compared with adding routine MCV2 (5·41, 4·76-6·11). Vaccination strategies, including non-selective SIAs, reach a greater proportion of children who are unvaccinated and reduce measles burden more than MCV2 alone, but efficiency is lower because of the wide age range targeted by SIAs. This analysis provides information to help improve the health effects and efficiency of measles vaccination strategies. The interplay between MCV1, MCV2, and SIAs should be considered when planning future measles vaccination strategies. Gavi, the Vaccine Alliance and the Bill & Melinda Gates Foundation.

Trend of immunity against measles and varicella zoster virus in healthcare workers in Korea

ObjectiveTo examine the seroprevalence of measles and varicella zoster virus (VZV) among healthcare workers (HCW) and evaluate the concordance between self-reported history of previous disease or vaccination and seropositivity. DesignA seroprevalence study and survey. SettingA university-affiliated tertiary care hospital. ParticipantsAll HCWs working in high-risk services in 2017 underwent serologic tests and survey; all new HCWs employed in the subsequent years, serologic tests only. MethodsA serologic study was conducted using chemiluminescence immunoassay (2017) or enzyme immunoassays (2018 and later). HCWs who underwent serological testing in 2017 completed a self-administered questionnaire on their history of infection and vaccination. ResultsA total of 10,278 and 9607 HCWs underwent serologic tests for measles and VZV IgG, respectively, from 2017 to 2022. The overall seropositivity rates for measles and VZV were 78.1 % and 92.8 %, respectively. Measles seropositivity declined gradually from >90 % in the HCWs born in the 1960s to <80 % in those born in the 1990s. There was a significant difference in measles seropositivity between the birth cohorts (BCs) 1967–1984 and 1985–1999 (P < 0.001; odds ratio, 1.16; 95 % confidence interval, 1.14–1.18). The seropositivity for VZV was stable, at >90 % in all BCs. The self-reported vaccination history was not independently associated with seropositivity, and the negative predictive value of the survey was very low (9.6 % and 13.1 %, respectively). ConclusionsMeasles seropositivity showed a substantial decline among HCWs born in 1985 or later, while varicella seropositivity remained high. The self-reported vaccination history was not sufficiently reliable for screening HCWs.

Uptake Of Covid-19 Vaccination Among Health Care Workers In A Tertiary Hospital In Northeast Nigeria

Background: The WHO declared COVID19 a public health emergency of international concern on January 30th, 2020, with millions infected and several deaths. Several countries began vaccinations targeting healthcare workers due to their increased risk of contracting the disease. Achieving high vaccine among healthcare workers is vital as it plays a major role in vaccine uptake among the general population. Objective: This study aimed at determining the uptake of COVID-19 vaccine uptake and the factors influencing it among healthcare workers at the Federal Teaching Hospital (FTH), Gombe. Methods: A descriptive cross-sectional study was conducted where 274 respondents were selected using a stratified sampling technique. Data was collected using a semi-structured interviewer-administered questionnaire. Data were analyzed using IBM SPSS version 23. Associations were explored with chi-square test and logistics regression analysis. The level of significance was set at 5%. Result: The mean age of the respondents was 35.88±8.49 years, and the majority were men (54.4%) and nurses (39.0%). Of the 274 respondents interviewed, 66.8% were willing to take the COVID-19 vaccine, while 59% actually did so. Bivariate analysis showed that age (p=0.006), working experience (p=0.025), chronic medical condition (p&lt;0.001), history of previous vaccination with other antigens (p=0.003) and history of positive COVID-19 test (p&lt;0.001) were associated with COVID-19 vaccine uptake. Logistic regression revealed that those with chronic medical conditions (OR=3.429 (CI:1,433-8.148), a history of previous vaccination (OR=3.018 (CI:1.119-8.148), and those who tested positive for COVID-19 (OR=2.823 (CI:1.630-4.901) were three times more likely than others to receive the COVID-19 vaccine..Conclusion:Low COVID-19 vaccine uptake was reported among healthcare workers of FTH, Gombe. Chronic medical conditions, history of previous vaccination and those with positive COVID-19 tests facilitated vaccine uptake. We advocate proper health education and community engagement among healthcare workers.

Views and perceptions of the public toward COVID-19 vaccine in Saudi Arabia

BackgroundNumerous surveys studied individuals’ decision to receive COVID-19 vaccine but the motives behind accepting or refusing COVID-19 vaccines are not yet fully understood. We aimed to more qualitatively explore the views and perceptions toward COVID-19 vaccines in Saudi Arabia to provide recommendations to mitigate the vaccine hesitancy issue. MethodsOpen-ended interviews were conducted between October 2021-January 2022. The interview guide included questions about beliefs in vaccine efficacy and safety, and previous vaccination history. The interviews were audio-recorded, transcribed verbatim, and the content was analyzed using thematic analysis. Nineteen participants were interviewed. ResultsAll of the interviewees were vaccine acceptors; however, three participants were hesitant as they felt they were forced to receive it. Several themes emerged as the reasons to accept or refuse the vaccine. The key reasons behind vaccine acceptance were the sense of obligation to fulfill a governmental command, trust in the government decisions, vaccine availability, and the impact of family/friends. The main reason behind vaccine hesitancy was doubts regarding vaccine efficacy and safety and that vaccines were pre-invented, and the pandemic is made-up. Participants’ sources of information included social media, official authorities, and family/friends. ConclusionFindings from this study show that the convenience of receiving the vaccine, the abundance of credible information from the Saudi authorities, and the positive influence of family/friends were among the major factors that encouraged the public in Saudi Arabia to get vaccinated against COVID-19. Such results may inform future policies regarding encouraging the public to receive vaccines in cases of pandemic.

Immunogenicity and safety of fractional doses of 17D-213 yellow fever vaccine in HIV-infected people in Kenya (YEFE): a randomised, double-blind, non-inferiority substudy of a phase 4 trial

Evidence indicates that fractional doses of yellow fever vaccine are safe and sufficiently immunogenic for use during yellow fever outbreaks. However, there are no data on the generalisability of this observation to populations living with HIV. Therefore, we aimed to evaluate the immunogenicity of fractional and standard doses of yellow fever vaccine in HIV-positive adults. We conducted a randomised, double-blind, non-inferiority substudy in Kilifi, coastal Kenya to compare the immunogenicity and safety of a fractional dose (one-fifth of the standard dose) versus the standard dose of 17D-213 yellow fever vaccine among HIV-positive volunteers. HIV-positive participants aged 18-59 years, with baseline CD4+ T-cell count of at least 200 cells per mL, and who were not pregnant, had no previous history of yellow fever vaccination or infection, and had no contraindication for yellow fever vaccination were recruited from the community. Participants were randomly assigned 1:1 in blocks (variable block sizes) to either a fractional dose or a standard dose of the 17D-213 yellow fever vaccine. Vaccines were administered subcutaneously by an unblinded nurse and pharmacist; all other study personnel were blinded to the vaccine allocation. The primary outcome of the study was the proportion of participants who seroconverted by the plaque reduction neutralisation test (PRNT50) 28 days after vaccination for the fractional dose versus the standard dose in the per-protocol population. Secondary outcomes were assessment of adverse events and immunogenicity during the 1-year follow-up period. Participants were considered to have seroconverted if the post-vaccination antibody titre was at least 4 times greater than the pre-vaccination titre. We set a non-inferiority margin of not less than a 17% decrease in seroconversion in the fractional dose compared with the standard dose. This study is registered with ClinicalTrials.gov, NCT02991495. Between Jan 29, 2019, and May 17, 2019, 303 participants were screened, and 250 participants were included and vaccinated; 126 participants were assigned to the fractional dose and 124 to the standard dose. 28 days after vaccination, 112 (96%, 95% CI 90-99) of 117 participants in the fractional dose group and 115 (98%, 94-100) of 117 in the standard dose group seroconverted by PRNT50. The difference in seroconversion between the fractional dose and the standard dose was -3% (95% CI -7 to 2). Fractional dosing therefore met the non-inferiority criterion, and non-inferiority was maintained for 1 year. The most common adverse events were headache (n=31 [12%]), fatigue (n=23 [9%]), myalgia (n=23 [9%]), and cough (n=14 [6%]). Reported adverse events were either mild (182 [97%] of 187 adverse events) or moderate (5 [3%]) and were self-limiting. Fractional doses of the 17D-213 yellow fever vaccine were sufficiently immunogenic and safe demonstrating non-inferiority to the standard vaccine dose in HIV-infected individuals with CD4+ T cell counts of at least 200 cells per mL. These results provide confidence that fractional dose recommendations are applicable to populations with high HIV prevalence. Wellcome Trust, Médecins Sans Frontières Foundation, and the UK Department for International Development.

Immunogenicity and safety of fractional doses of 17D-213 yellow fever vaccine in children (YEFE): a randomised, double-blind, non-inferiority substudy of a phase 4 trial

Current supply shortages constrain yellow fever vaccination activities, particularly outbreak response. Although fractional doses of all WHO-prequalified yellow fever vaccines have been shown to be safe and immunogenic in a randomised controlled trial in adults, they have not been evaluated in a randomised controlled trial in young children (9-59 months old). We aimed to assess the immunogenicity and safety of fractional doses compared with standard doses of the WHO-prequalified 17D-213 vaccine in young children. This substudy of the YEFE phase 4 study was conducted at the Epicentre Mbarara Research Centre (Mbarara, Uganda). Eligible children were aged 9-59 months without contraindications for vaccination, without history of previous yellow fever vaccination or infection and not requiring yellow fever vaccination for travelling. Participants were randomly assigned, using block randomisation, 1:1 to standard or fractional (one-fifth) dose of yellow fever vaccine. Investigators, participants, and laboratory personnel were blinded to group allocation. Participants were followed for immunogenicity and safety at 10 days, 28 days, and 1 year after vaccination. The primary outcome was non-inferiority in seroconversion (-10 percentage point margin) 28 days after vaccination measured by 50% plaque reduction neutralisation test (PRNT50) in the per-protocol population. Safety and seroconversion at 10 days and 12-16 months after vaccination (given COVID-19 resctrictions) were secondary outcomes. This study is registered with ClinicalTrials.gov, NCT02991495. Between Feb 20, 2019, and Sept 9, 2019, 433 children were assessed, and 420 were randomly assigned to fractional dose (n=210) and to standard dose (n=210) 17D-213 vaccination. 28 days after vaccination, 202 (97%, 95% CI 95-99) of 207 participants in the fractional dose group and 191 (100%, 98-100) of 191 in the standard dose group seroconverted. The absolute difference in seroconversion between the study groups in the per-protocol population was -2 percentage points (95% CI -5 to 1). 154 (73%) of 210 participants in the fractional dose group and 168 (80%) of 210 in the standard dose group reported at least one adverse event 28 days after vaccination. At 10 days follow-up, seroconversion was lower in the fractional dose group than in the standard dose group. The most common adverse events were upper respiratory tract infections (n=221 [53%]), diarrhoea (n=68 [16%]), rhinorrhoea (n=49 [12%]), and conjunctivitis (n=28 [7%]). No difference was observed in incidence of adverse events and serious adverse events between study groups. Fractional doses of the 17D-213 vaccine were non-inferior to standard doses in inducing seroconversion 28 days after vaccination in children aged 9-59 months when assessed with PRNT50, but we found fewer children seroconverted at 10 days. The results support consideration of the use of fractional dose of yellow fever vaccines in WHO recommendations for outbreak response in the event of a yellow fever vaccine shortage to include children. Médecins Sans Frontières Foundation.

Previous Vaccination History and Psychological Factors as Significant Predictors of Willingness to Receive Mpox Vaccination and a Favorable Attitude towards Compulsory Vaccination.

During the ongoing multi-country monkeypox (Mpox) outbreak, healthcare workers (HCWs) have represented a key group in mitigating disease spread. The current study aimed to evaluate the attitude of nurses and physicians in Jordan towards Mpox vaccination, as well as their attitude towards compulsory vaccination against coronavirus disease 2019 (COVID-19), influenza, and Mpox. An online survey was distributed in January 2023 based on the previously validated 5C scale for psychological determinants of vaccination. Previous vaccination behavior was assessed by inquiring about the history of getting the primary and booster COVID-19 vaccination, influenza vaccine uptake during COVID-19, and any history of influenza vaccine uptake. The study sample consisted of 495 respondents: nurses (n = 302, 61.0%) and physicians (n = 193, 39.0%). Four hundred and thirty respondents (86.9%) had heard of Mpox before the study, and formed the final sample considered for Mpox knowledge analysis. Deficiencies in Mpox knowledge were reflected in a mean knowledge score of 13.3 ± 2.7 (out of 20.0 as the maximum score), with significantly lower knowledge among nurses and females. The intention to receive Mpox vaccination was reported by 28.9% of the participants (n = 143), while 33.3% were hesitant (n = 165), and 37.8% were resistant (n = 187). In multivariate analysis, Mpox vaccine acceptance was significantly associated with previous vaccination behavior, reflected in higher vaccine uptake and with higher 5C scores, while Mpox knowledge was not correlated with Mpox vaccination intention. The overall attitude towards compulsory vaccination was neutral, while a favorable attitude towards compulsory vaccination was associated with higher 5C scores and a history of previous vaccination uptake. The current study showed a low intention to get Mpox vaccination in a sample of nurses and physicians practicing in Jordan. The psychological factors and previous vaccination behavior appeared as the most significant determinants of Mpox vaccine acceptance and of attitudes towards compulsory vaccination. The consideration of these factors is central to policies and strategies aiming to promote vaccination among health professionals in efforts to prepare for future infectious disease epidemics.

Abstract 5539: Assessing knowledge, vaccine hesitancy, and completion rates of free HPV vaccination in uninsured/underinsured low-income patients

Abstract Background: Human Papillomavirus (HPV) vaccination rates remain low in the U.S., particularly among minorities and low-income patients. In 2014, a Mayo Clinic study of uninsured, low-income, working, Volunteer in Medicine (VIM) Clinic patients in Jacksonville, Florida found a statistically significant lower awareness of HPV (50.3% vs 63.6%) and the HPV vaccine (32.1% vs 62.7%) than the national population. As a result, our team collaborated with Merck to develop a free HPV vaccination program and video education campaign for VIM patients. Methods: We assessed VIM patients HPV vaccination knowledge, awareness, and prevalence of hesitancy towards receiving the vaccine. VIM patients (ages 18-45) with no previous history of HPV vaccination were invited to participate in this study. The Parents Attitudes about Childhood Vaccines (PACV) survey was used to evaluate vaccine hesitancy. Patients who declined the HPV vaccine were shown an educational video to assess effectiveness in persuading patients’ opinion. Each participant received a vaccine hesitancy PACV score, which was compared with their vaccine disposition. Mayo Clinic IRB approval of the study was obtained. Results: Our analysis included 43 patients (34 females, 9 males) with a median age of 40 (age range 27- 45). Patients had overall knowledge of HPV of 88.4%, with 69.8% having heard of the HPV vaccine. 85.7% PACV survey respondents were deemed non-hesitant (PACV scores 0-49), and 80.6% of the non-hesitant subset (29/36) agreed to undergo vaccination. The average PACV score of vaccine-interested participants was lower (25.2) than the average of participants not interested in the vaccine (36.7). Black participants had a statistically significant higher PACV score than White participants. The PACV scores of individuals who were already familiar with the HPV vaccine were significantly lower than those of participants who were unfamiliar with the HPV vaccine. Only 20% (2/10) of individuals, who had previously declined vaccination, agreed to receive the HPV vaccine after viewing the HPV educational video. Of the 33 participants who agreed to receive the free HPV vaccine, only 9 (27.3%) completed all three doses. Conclusions: HPV vaccine awareness and knowledge at VIM increased compared to the 2014 cohort. Vaccine hesitancy was not observed in most patients, yet video education was effective in only a small portion of patients with vaccine hesitancy. Additionally, a minority of patients who agreed to receive the free HPV vaccine series completed all three doses. Our results suggests that free HPV vaccination and video education is not sufficient to achieve adequate vaccination rates among low-income uninsured young adults, nor overcoming vaccine hesitancy. Innovative measures are warranted to improve vaccination rates in this population. Citation Format: Hiram Diaz, Gerardo Colon-Otero, Laura M. Pacheco-Spann, Christopher C. DeStephano, Sandra Casanova-Leyva. Assessing knowledge, vaccine hesitancy, and completion rates of free HPV vaccination in uninsured/underinsured low-income patients. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5539.

Association between COVID-19 and Seasonal Influenza Vaccines to Vaccine Hesitancy, Intolerance of Uncertainty and Mental Health.

Vaccine hesitancy is a universal problem that is becoming more prevalent, ranging from partial acceptance to the complete refusal of various vaccines. The current study seeks to assess the relationship between vaccine hesitancy, intolerance of uncertainty, and mental health factors and those who were vaccinated against COVID-19 and seasonal influenza in comparison to those who did not vaccinate against both or decided to be vaccinated with only one of these vaccines. Employing a cross-sectional design, 1068 Israeli participants were recruited via social media (mainly Facebook) and Whatsapp and completed questionnaires assessing vaccine hesitancy, intolerance of uncertainty, and mental health factors. Our results revealed that previous history of neither COVID-19 nor seasonal influenza vaccination was associated with increased vaccine hesitancy. In addition, individuals who received either one vaccine or both claimed elevated levels of intolerance of uncertainty and reported elevated levels of mental health symptoms. Therefore, an association between vaccine hesitancy and intolerance of uncertainty and mental health symptoms is demonstrated. Future campaigns against vaccine hesitancy may focus on the intolerance of uncertainty in vaccine-hesitant individuals.

The refusal of COVID-19 vaccination and its associated factors: a systematic review

Background: To date, more than 10% of the global population is unvaccinated against the coronavirus disease 2019 (COVID-19), and the reasons why this population is not vaccinated are not well identified. Objectives: We investigated the prevalence of COVID-19 vaccine refusal and to assess the factors associated with COVID-19 vaccine refusal. Methods: A meta-analysis was conducted during August to November 2022 (PROSPERO: CRD42022384562). We searched articles investigating the refusal of COVID-19 vaccination and its potential associated factors in PubMed, Scopus, and the Web of Sciences. The quality of the articles was assessed using the Newcastle–Ottawa scale, and the data were collected using a pilot form. The cumulative prevalence of the refusal to vaccinate against COVID-19 was identified using a single-arm meta-analysis. The factors associated with COVID-19 vaccine refusals were determined using the Mantel-Haenszel method. Results: A total of 24 articles were included in the analysis. Our findings showed that the global prevalence of COVID-19 vaccine refusal was 12%, and the highest prevalence was in the general population, and the lowest prevalence was in the healthcare worker subgroup. Furthermore, individuals with a high socioeconomic status, history of previous vaccination, and medical background had a lower rate of COVID-19 vaccination refusal. Subsequently, the following factors were associated with an increased risk of COVID-19 vaccine refusal: being female, educational attainment lower than an undergraduate degree, and living in a rural area. Conclusion: Our study identified the prevalence of and factors associated with COVID-19 vaccine refusal. This study may serve as an initial reference to achieve global coverage of COVID-19 vaccination by influencing the population of COVID-19 vaccine refusal.