Booster Dose Of Vaccine Research Articles

Long-term serological response and boostability of intradermal rabies immunization: A retrospective chart review.

Rabies vaccines in Canada are currently labeled for intramuscular use only; however, intradermal vaccine administration may be equally effective. This study aims to assess the immediate and long-term (≥ 2years) serological response and boostability of intradermal administration of rabies vaccine for pre-exposure prophylaxis. This retrospective cohort study was conducted using data from electronic medical records at the Winnipeg Regional Health Authority Travel Health & Tropical Medicine Services Clinic. Individuals ≥ 18years of age at time of vaccination who received at least 3 × 0.1mL doses of intradermal rabies vaccine were included. All charts were reviewed to extract post-primary immunization and post-booster serology results, and t-tests were conducted to evaluate seroprotection (defined as serology ≥ 0.5IU/mL). A total of 324 individuals received an intradermal rabies primary pre-exposure vaccination series with follow-up serology within 90days. Seroprotection was observed in 96% (GMT = 3.36IU/mL, 95% CI 3.07-3.68). Of these, 68 had serology results 1.8-2.5years later, with seroprotection declining to 44% (GMT = 0.52IU/mL, 95%CI 0.41-0.65). However, 100% seroprotection was observed in those who received an intradermal booster dose at ≥ 2years with follow-up serology (n = 20, GMT = 4.7IU/mL, 95%CI 3.7-6.2). Intradermal administration of a primary pre-exposure rabies vaccine series demonstrates a strong serological response. While titers decline over time, the robust serological response demonstrated after a single intradermal booster vaccine dose suggests that a strong anamnestic immune response was maintained. This finding supports existing evidence that intradermal administration of rabies vaccines can be used effectively for rabies pre-exposure and post-exposure prophylaxis.

Frequency and determinants of acceptance of COVID-19 vaccine booster dose among health care providers: a cross-sectional study

BackgroundAs the COVID-19 virus spreads, it has new opportunities to change, and new variants of the virus are expected to occur. Health care workers (HCWs) are potential victims of the disease and spread it. They are more vulnerable to infection due to their occupational and nonoccupational exposure. The aim of this study was to identify the frequency and determinants of the acceptance of health care providers to receive the booster dose of COVID-19 vaccine.MethodsAn online questionnaire was used to collect data by the Egyptian HCWs. The questionnaire had four sections: the first section included the participants’ sociodemographic data, the second section included data on the participants’ previous COVID-19 infection status, the third section was on COVID-19 vaccine-related information, and the fourth section evaluated the intention to take the booster dose, causes of acceptance or refusal, and any suggestions to combat COVID-19.ResultsA total of 413 HCWs completed the questionnaire. Females represented 79.9%, and 37.3% had direct contact with COVID-19 patients, and 61.7% had previous infection. The vast majority (94.2%) received COVID-19 vaccine, 52.1% agreed to receive the booster dose, while 47.9% refused. The most common reason to receive booster dose was for increasing protection against new variants (48.4%) and lowering rate of severe illness and hospitalization (41.4%). Male gender and previous COVID-19 vaccination were the main determining factors of acceptance to receive booster doses.ConclusionAcceptance of COVID-19 booster vaccination was relatively inadequate among the HCWs. Male gender and previous COVID-19 vaccination were determinants of acceptance.

Factors related to acceptance of COVID-19 vaccine booster doses among patients with autoimmune and rheumatic diseases in Japan: A single-center cross-sectional survey.

We studied the current state and factors associated with the acceptance or hesitancy of booster doses of the coronavirus disease 2019 (COVID-19) vaccine among patients with autoimmune and rheumatic diseases (ARDs) in Japan. A single-center cross-sectional survey was conducted among outpatients with ARDs who visited the Immuno-Rheumatology Center at St. Luke's International Hospital from 1 October to 30 November in 2023. We investigated patient characteristics, COVID-19 vaccination-related status, decision-making preferences, health-related status and independent factors associated with the acceptance or hesitancy of booster doses of the COVID-19 vaccine. A total of 241 patients were included in the analyses, and 198 patients (82.2%) received booster doses while 43 (17.8%) did not. Older age (adjusted odds ratio [aOR] = 0.43, 95% CI: 0.19, 0.95, P = 0.037), having rheumatoid arthritis (RA) (aOR = 0.41, 95% CI: 0.19, 0.92, P = 0.030) and having a physician recommend receiving the vaccine (aOR = 0.47, 95% CI: 0.23, 0.95, P = 0.035) were independently associated with receiving booster doses. The main reasons for hesitancy regarding booster doses were concerns about adverse reactions and long-term safety. Our findings could help physicians counsel patients with ARDs regarding their acceptance of COVID-19 vaccine booster doses to promote appropriate decision-making.

Factors associated with outcome in a national cohort of rhinovirus hospitalized patients in Brazil in 2022

The common cold is the primary cause of illness in the community, with over 200 viral strains identified, and rhinovirus infections being the most prevalent. Coronavirus Disease 19 (COVID-19) is also a significant cause of severe illness. The burden of acute respiratory infections has a significant impact on the economy, resulting in absenteeism from work and school. Rhinovirus infections can exacerbate asthma and other chronic diseases, leading to hospitalization. The objective of this study is to investigate the factors associated with death and survival in patients hospitalized for rhinovirus in Brazil in 2022. This is a retrospective cohort study using data from the national surveillance of Severe Acute Respiratory Syndrome (SARS) in 2022 in Brazil, with all the norrifications. We analysed and compared clinical and epidemiological factors and outcomes between survivors and deaths in patients hospitalised for rhinovirus. The absolute and relative frequencies were calculated according to the states. Bivariate analysis was performed using chi-squared test and Fisher’s exact test, while multivariate analysis was performed using COX regression. Out of 8,130 cases of SARS caused by rhinovirus, 291 (3.58%) resulted in death while 7839 (96.47%) patients survived. The factors associated with death were invasive ventilation (p- < 0.001 HR 4.888 CI 95% 3.816–6.262), bocavirus (p- < 0.001 HR 4.204 CI 95% 2.595–6.812), immunodepression/Immunosuppression (p- < 0.001 HR 2.417 CI 95% 1. 544–3, 786), COVID-19 (p- < 0.001 HR 2.167 CI 95% 1.495–3.142), chronic neurological diseases (p-0.007 HR 1.610 CI 95% 1.137–2.280), abdominal pain (p-0.005 HR 1.734 CI 95% 1.186–2.537), age (p- < 0.001 HR 1.038 CI 95% 1.034–1.042). The survival factors identified in this study were dyspnea (p = 0.005; HR 0.683; CI 95% 0.524–0.889), cough (p < 0.001; HR 0.603; CI 95% 0.472–0.769), and asthma (p = 0.052; HR 0.583; CI 95% 0.339–1.004). Additionally, the study found that receiving a COVID-19 booster dose was also a significant survival factor (p = 0.001; HR 0.570; CI 95% 0.415–0.784). The factors associated with death were similar to those in the literature, and the factors associated with survival were also similar, except for the booster dose of the COVID-19 vaccine, which we didn’t find in any studies. Our study is the first to associate the full course of the COVID-19 vaccine with survival in those hospitalized for rhinovirus, regardless of COVID-19 and rhinovirus co-detection.

Acceptance and Perceptions of COVID-19 Booster Dose; A Survey among Residents of Rawalpindi

Objectives: To determine public acceptance of COVID-19 booster dose, to know about perceptions and possible barriers regarding the vaccine. Study design: Analytical cross sectional study. Place and Duration of Study: conducted regarding the acceptance and perception of the vaccine booster dose among the residents of Rawalpindi Pakistan. The duration of study was 3 months i.e. from Jun till Aug 2022 Methodology: The sample size was 320 and collected using convenient sampling technique. The study included residents of Rawalpindi between ages 18 and 65. Google forms based on Health Belief Model were used for data collection. Data analysis was done using SPSS version 28 and summary statistics were produced using frequencies, percentages and mean. Chi-square test was also used to determine associations between categorical variables. Results: The results revealed that 74% of the participants’ primary reason for getting booster dose was their own safety while major barrier to booster dose vaccination was side effects related to vaccine - 62%. 81.3% people were willing to get the booster dose and 87.9% people agreed to receive booster dose for free. Chi-square test indicated a significant association between acceptance and perceived susceptibility, benefits and severity. Conclusion: In conclusion, our findings reveal that majority of people were willing to get booster dose primarily for own safety. However, counselling is required to decrease the perceived barriers to vaccination regarding side effects of the vaccine.

Comparative analysis of COVID-19 vaccine booster dose (VBD) acceptance among trainees and students of health professions in Bangladesh

BackgroundDespite the proven therapeutic potential of bivalent vaccine primer doses against COVID-19, acceptance of vaccine booster doses (VBD) varies among various subgroups of the global population. This study investigated the acceptance of COVID-19 VBD among trainees and students of health professions in Bangladesh and compared the potential factors influencing their VBD decisions. MethodsThe questionnaire was deployed in an online-enabled layout and conveniently sent to encounters between 10th June 2023 and 10th September 2023. Data from 501 trainees and 501 students were compared (response rate 80.8% vs.78.3%) to explore the study objectives. ResultsThe pooled COVID-19 VBD acceptance rates were 90.2% (95% Confidence Interval [CI]:87.6─92.8) vs. 93.2% (95% [CI]: 91.2─95.2) between trainees and students. The binary logistic analysis revealed that out of twelve factors “equal safety” (Adjusted odds ratio [aOR]: 4.476 vs. 6.459), “efficacy” ([aOR]:3.673 vs. 2.913), “repeated immunity” ([aOR]: 1.729 vs. 2.247), and “self-priority” ([aOR]:3.108 vs. 4.645) had a significant positive association (p<0.01 and p<0.05) with VBD acceptance in both groups. There were varied effects on several predictors. Among trainee professionals, "communication" and "booster mandate" were associated significantly ([aOR]:1.534 and 1.748, respectively; p<0.05) with VBD acceptance, whereas "information source" and "culture" were associated ([aOR]:3.692 and 3.151, respectively; p<0.05) significantly with VBD acceptance in the student cohort. ConclusionsThere was a satisfactory acceptance level of COVID-19 VBD among healthcare participants, and several multidimensional factors influenced their VBD decisions in different ways. For enhancing public booster immunization decisions against COVID-19, individual health expectations must be linked to wider societal influences.

First bipolar episode following booster dose of COVID-19 vaccination

Introduction and importance: The interactions between the susceptibility of the host and some of the COVID-19 vaccine components happened. Viral infections, including COVID-19, are related to the pathogenesis of bipolar disorder (BD). These findings could trigger an initial bipolar episode. Case presentation: A 48-year-old Syrian married female, presented to the out-clinic of Modern Medical Centre Hospital, in July 2022 for episodes of sub-maniac/mania episodes, which began within 15 days after the booster dose of COVID-19 vaccination, preceded by depressive mood. Both family and personal past psychiatric and/or trauma history were negatives. Initiation of carbamazepine 600 mg/day showed significant improvement within 3 days; 3 months later, carbamazepine dose was decreased to 200 mg/day, as there were no clinical symptoms. Clinical discussion: mRNA vaccines of COVID-19 increase the levels of type I interferon (INF), an inflammatory cytokine that creates a signal leading to the expression of interleukins, INF, and tumor necrosis factor-alpha. The pathology of BD is also unclear. Genetic predisposition, immunological effects, and the classification of BD, itself, as an autoimmune disease play a role. Although rapid improvement following treatment, prolonged and maintenance treatment by essentially mood stabilizer should be considered in bipolar episodes initiated by COVID-19 vaccination. Rare data are available about maniac episodes after COVID-19 infection, but to our knowledge, we reported the first case of bipolar onset after the booster vaccination of COVID-19. Conclusion: Bipolar disease can present following a booster dose of COVID-19 vaccination in previously healthy people.

Analysis of immunological and biochemical parameters after booster dose vaccination using protein-based and inactivated virus vaccine for safety

IntroductionHeterologous vaccines enhance the immune response to new variants and allow flexibility in booster administration when the original vaccine is unavailable. Studies show that heterologous boosters can generate comparable or superior antibody responses compared to homologous boosters. Considering rare side effects is essential in evaluating COVID-19 vaccines, especially those associated with ChAdOx1-S (AstraZeneca) and Ad26.COV2.S (Janssen), including blood clotting and idiopathic thrombocytopenia. Severe side effects, such as myocarditis and pericarditis, may occur after Pfizer or Moderna boosters but are rare. MethodsThis study administered two vaccines: the Sinopharm inactivated virus vaccine and the Razi-CoV-Pars (RCP) booster. Various evaluations included biochemical markers, coagulation factors, autoimmune antibodies, and antibodies against concerning variants. ResultsAll 90 participants exhibited a notable rise in antibody levels against the variant of concern (VOC). Participants receiving the Razi-CoV-Pars booster after Sinopharm/BBIBP-CorV showed significantly higher antibody levels (Wuhan ∼ 3.25 times, Delta ∼4 times, Omicron ∼ 14 times) compared to those receiving Sinopharm's homologous vaccine. No significant changes (P: <0.05) were found in LDH, CPK, CK-MB, ANA, and Anti-CCP levels. However, individuals receiving Sinopharm's booster after two doses showed a significant increase (4 cases) in D-Dimer levels. ConclusionThe Razi-CoV-Pars vaccine demonstrates a favorable safety profile and promising potential as an effective booster against current variants, particularly due to its significant protective titer against Omicron.

Antibody Response After a Fifth Dose (Third Booster) of BNT162b2 mRNA COVID-19 Vaccine in Healthcare Workers.

Although a fourth dose of SARS-CoV-2 vaccine was shown to be effective, the immunogenicity of a fifth dose in immunocompetent individuals had not been well described. This was a prospective observational cohort study of previously vaccinated healthcare workers at a single tertiary hospital in Israel. Individuals were administered up to three booster doses of the BNT162b2 mRNA vaccine (i.e., up to five overall doses), during the period between July 2021 and January 2023. Immunogenicity was assessed using the SARS-CoV-2 IgG (sCOVG) semi-quantitative assay, performed at several time points. The cohort consisted of 162 individuals (median age 69 years, 62% female). Of these, 104 (64%) received four doses and 58 (36%) received five doses. Anti-SARS-CoV-2 antibody levels increased in all cases, regardless of the baseline levels. The fold-change increase in the mean sCOVG index was 29.2 (SD 2.6) after the third vaccine, 3.8 (SD 2.4) after the fourth vaccine, and 3.6 (SD 3.0) after the fifth vaccine. A waning effect over time was seen in 78% and 43% of participants for the third and fourth doses, respectively. Adverse events following the fifth dose were limited and mild. Similar to previous booster vaccines, a fifth dose of BNT162b2 is immunogenic and safe in healthy individuals, although the clinical implications remain unclear.

Effect of RTS,S/AS01E vaccine booster dose on cellular immune responses in African infants and children

RTS,S/AS01E, the first approved malaria vaccine, demonstrated moderate efficacy during the phase 3 pediatric trial. We previously investigated cell-mediated immune (CMI) responses following the primary 3-dose immunization and now report responses to the booster dose given 18 months later. Thirty CMI markers were measured by Luminex in supernatants of peripheral blood mononuclear cells from 709 children and infants after RTS,S/AS01E antigen stimulation, and their associations with malaria risk and antibodies one month post-booster and one year later were assessed. IL-2, IFN-γ, IL-17, IL-5, and IL-13 were associated with RTS,S/AS01E booster vaccination, and IL-2 responses to the circumsporozoite protein (CSP) remained higher after one year. IL-2 was associated with reduced malaria risk in one site, and IL-10 was associated with increased risk in infants. Anti-CSP IgG and IL-2 were moderately correlated one year after booster. This study highlights the moderate cell-mediated immunogenicity of the RTS,S/AS01E booster dose that aligns with partial recovery of RTS,S/AS01E vaccine efficacy.

Humoral Response to SARS-CoV-2 Vaccine-Boost in Cancer Patients: A Case Series from a Southern European Cancer Center.

Cancer patients face a greater risk of complications and death after contracting the SARS-CoV-2 virus. Booster doses of the COVID-19 vaccine were suggested to provide additional protection. This study aimed to assess how cancer patients' immune systems respond to the booster shots and categorize their responses. We analyzed 735 samples from 422 individuals, including patients followed at the Portuguese Oncology Institute of Porto (IPO-Porto). Three cohorts were recruited, and blood samples were collected 3- and 6-months post-booster dose: cohort 1 cancer patients (also collected before the booster); cohort 2 cancer patients; and cohort 3 (healthy individuals). Humoral immune response was evaluated by analyzing IgG levels against the SARS-CoV-2 Spike (S) protein. IgG levels against the SARS-CoV-2 Nucleocapsid(N) protein was also analyzed in order to address previous contact with the virus. Among Cohort 1 patients with solid tumors, when compared to pre-boost, IgG S levels increased 3 months after the boost and remained high after 6 months. Patients with hematologic tumors demonstrated lower IgG S levels at both timepoints. Comparing the IgG S levels among hematological tumors, solid tumors, and healthy individuals in both timepoints we observed that the healthy individuals had the strongest IgG S response, followed by the solid, and, lastly, the hematologic tumors. Solid tumor patients undergoing chemotherapy had reduced IgG S levels, especially those on high febrile neutropenia risk regimens. In conclusion, cancer patients have a weaker immune response to the SARS-CoV-2 vaccine, especially those with hematological cancers. Chemotherapy and febrile neutropenia risk further reduce booster effectiveness. Further research is needed to optimize vaccine timing for cancer patients undergoing chemotherapy.

Risk of major adverse cerebro-cardiovascular events following BNT162b2, CoronaVac, and ChAdOx1 vaccination and SARS-CoV-2 infection: A self-controlled case-series study

ObjectiveTo assess the potential risk of major adverse cerebro-cardiovascular events (MACCE) associated with COVID-19 vaccination and SARS-CoV-2 infection. MethodsThis self-controlled case series study used nationwide health database from Malaysia. The study included individuals aged ≥18 years who were hospitalised between 24 February 2021 and 30 June 2022. Outcomes were composite of MACCE: stroke, acute ischaemic heart disease, and cardiovascular death. Exposures were COVID-19 vaccination and SARS-CoV-2 infection. The risk period was day 1 to day 21 following exposure. Conditional Poisson regression model was used to estimate the incidence rate ratios (IRRs) and 95 % confidence interval (CI) comparing the outcomes in the risk and control periods. ResultsThe risk of MACCE within 21 days after vaccination per 100,000 doses administered were 12.0 (95% CI 11.9–12.1) (BNT162b2), 9.2 (95% CI 9.1–9.3) (CoronaVac), and 6.8 (95% CI 6.6–7.0) (ChAdOx1). The incidence rate ratios showed no increased risk of MACCE associated with the first, second, or third doses of BNT162b2, CoronaVac, and ChAdOx1 vaccines for individuals without prior cardiovascular disease (CVD). This finding was consistent for individuals with CVD. Vaccine booster dose, whether in a homologous or heterologous schedule, did not show increased risk of MACCE. Analysis by ethnic groups detected a slightly elevated risk of MACCE in Indian after the first dose of ChAdOx1 (IRR 1.64; 95% CI 1.08–2.48) in those without CVD. No significant association were observed in other subgroup analyses. SARS-CoV-2 infection was associated with significantly increased risk of MACCE in individuals without CVD (IRR 3.54; 95% CI 3.32–3.76) and with CVD (IRR 1.98; 95% CI 1.61–2.34). ConclusionsOur findings support the favourable safety profile of these COVID-19 vaccines and indicate that the overall benefit-risk ratio of the COVID-19 vaccines remains positive.

Protection conferred by booster vaccine doses in hospitalized patients with COVID-19 during the SARS-CoV-2 Omicron BA.2 and BA.5 epidemics from 2022 to 2023 in Greece

BackgroundTo estimate the protection that coronavirus disease 2019 (COVID-19) vaccine doses conferred to hospitalized patients with COVID-19 against adverse outcomes and longer length of stay during the Omicron BA.2 and BA.5 subvariant epidemics in Greece. MethodsThe study was conducted from November 2022 to May 2023. Multivariable logistic and negative binomial regression models were applied to estimate the association between any adverse outcomes and length of stay with the number of COVID-19 vaccine doses. ResultsWe studied 962 patients (median age: 78 years; mean length of stay: 9.2 days), of whom 847 (88.0%) had ≥ 1 comorbidity. Of these, 39 (4.0%) were admitted to the intensive care unit, 44 (4.6%) received invasive mechanical ventilation, and 110 (11.4%) died in hospital. There were 184 (19.1%) unvaccinated patients, 125 (13.0%) with one or two vaccine doses, and 653 (67.9%) with ≥ 3 doses. In multivariable analyses, patients with ≥ 3 doses had lower odds of experiencing any adverse outcomes (adjusted odds ratio: 0.57; 95% confidence interval [CI]: 0.37–0.86) compared with unvaccinated patients. On average, patients with one or two doses and those with ≥ 3 had decreased length of hospital stay (−1.5 days [95% CIs: −2.6 to −0.4] and −2.8 days [95% CIs: −4.1 to −1.4], respectively] compared with unvaccinated patients. Other characteristics consistently associated with adverse outcomes and longer length of stay included older age, having three or more comorbidities compared with none, and being admitted to the hospital two or more weeks post-diagnosis. ConclusionsA history of ≥ 3 vaccine doses conferred significant protection against any adverse outcome and longer length of stay in hospitalized patients with COVID-19.

Safety and immunogenicity of a modified mRNA-lipid nanoparticle vaccine candidate against COVID-19: Results from a phase 1, dose-escalation study

ABSTRACT This phase 1, open-label, dose-escalation, multi-center study (NCT05477186) assessed the safety and immunogenicity of a booster dose of an mRNA COVID-19 vaccine (CV0501) encoding the SARS-CoV-2 Omicron BA.1 spike protein. Participants aged ≥ 18 years previously vaccinated with ≥ 2 doses of an mRNA COVID-19 vaccine received CV0501 doses ranging from 12 to 200 μg. After assessment of safety and immunogenicity of the 12 μg dose in 30 adults, 30 adults ≤ 64 years were randomized to receive either a 3 or 6 μg dose. Solicited adverse events (AEs) were collected for 7 days, unsolicited AEs for 28 days, and serious AEs (SAEs), medically attended AEs (MAAEs), and AEs of special interest (AESIs) until day (D) 181 post-vaccination. Serum neutralizing titers specific to SARS-CoV-2 BA.1, wild-type, Delta, and additional Omicron subvariants were assessed at D1, D15, D29, D91, and D181. Of 180 vaccinated participants (mean age: 49.3 years; 57.8% women), 70.6% had prior SARS-CoV-2 infection. Most solicited local (98.1%) and systemic (96.7%) AEs were of mild-to-moderate severity; the most common were injection site pain (57.5%; 33.3–73.3% across groups) and myalgia (36.9%; 13.3–56.7%). Unsolicited AEs were reported by 14.4% (6.7–26.7%) of participants (mild-to-moderate severity in 88.5% of the participants). Three participants (1.7%) reported SAEs, 16.7% (6.7–30.0%) reported MAAEs, and 8.3% (0.0–13.3%) reported AESIs (15 COVID-19 cases), none related to vaccination. Geometric means of serum neutralizing titers increased from baseline to D15 and D29 (dose-dependent), and then decreased over time. The safety and immunogenicity results supported advancement to a phase 2 trial.

BNT162b2 vaccine booster dose did not influence the activity of the exudative form of age-related macular degeneration during anti-vascular endothelial growth factor therapy.

Due to safety concerns, patients were hesitant to receive a booster dose of COVID-19 vaccine. In this study, we investigated whether neovascular age-related macular degeneration activity deteriorated after receiving the booster dose of the BNT162b2 vaccine. Optical coherence tomography (OCT) of the macula, best-corrected visual acuity (BCVA), and slit-lamp examination data were collected from 89 patients. All these individuals were diagnosed with neovascular age-related macular degeneration (AMD) and treated with intravitreal injections of aflibercept or ranibizumab. During the process of treatment, patients received a booster dose of the BNT162b2 vaccine. Time points included two visits before (marked as "-2", "-1") and two visits after (marked as "1", "2") the uptake of the booster dose. There were significant differences in the average thickness and total volume of the macula during follow-up. Moreover, a decreased average thickness, total volume, total thickness of the macula, subretinal fluid thickness, and subretinal complex thickness was observed between the time points "-2" and "2", but only in the aflibercept group. There were no significant differences in the frequency of occurring intraretinal cysts, subretinal fluid, serous retinal pigment epithelial detachments retinal hemorrhage, subretinal hyperreflective material, complete RPE and outer retinal atrophy, and BCVA before and after the booster dose. These results demonstrate that the BNT162b2 vaccine booster dose did not deteriorate the course of neovascular AMD.

Assessing vaccinated persons’ intention to take the COVID-19 boosters using a combined theoretical framework: an online survey in Egypt

Vaccines, like the Corona Virus Disease-2019 (COVID-19) vaccines, can control diseases, but vaccine hesitancy reduces their use. It is important to assess the intention to use COVID-19 vaccines boosters and the determinants of this intention to help in developing programs to promote the uptake of boosters. An online survey collected data from adults in Egypt between March and June 2022 using a questionnaire that assessed demographic characteristics, and constructs of the Theory of Planned Behaviour (TPB) and the Health Belief Model (HBM). The survey was uploaded to SurveyMonkey and the links were posted on social media platforms. Binary regression analysis was used and the dependent variable was intention to use boosters of COVID-19 vaccines. The independent variables were indicators of the HBM including perceived susceptibility to COVID-19 infection (medical history) and possibility of disease prevention (awareness of the availability of types of COVID-19 vaccines); and indicators of the TPB including attitude toward COVID-19 vaccines (that they are harmful, that they may lead to death and confidence in locally and foreign manufactured vaccines), perceived norms (the percentage of vaccinated persons in one’s circle) and perceived control over booster uptake (presence of government mandates for COVID-19 vaccination). The confounders were sociodemographic factors (age, sex, education, and place of residence). Complete responses were available from 1113 out of 1401 participants (79.4%), with mean (SD) age = 25 (9.5) years, of whom, 66.7% (n = 742) were females and 68.6% (n = 764) were university students. About 39.4% and 31.2% indicated that they would get or would definitely get the booster dose of the COVID-19 vaccines. In multiple regression, intention to use a booster dose was significantly related to not agreeing (AOR = 4.87, P < 0.001) or not agreeing at all (AOR = 8.46, P = 0.001) that vaccines are harmful and to having no confidence (AOR = 0.21, P < 0.001) or no confidence at all (AOR = 0.14, P < 0.001) in foreign-manufactured vaccines. Most university-educated Egyptians in the study intended to take the COVID-19 vaccine booster dose and this intention was associated with attitude toward the harm of the vaccine and confidence in foreign-manufactured vaccines. Awareness campaigns are needed to counteract misinformation and promote booster dose uptake.

Evidence brief on facilitators, barriers and hesitancy of COVID-19 booster doses in Canada.

Understanding the facilitators, barriers and hesitancy to accepting COVID-19 booster doses is important for encouraging recommended vaccination. This evidence brief summarizes literature on the intention to accept or reject COVID-19 vaccine booster doses and the factors associated with intention/uptake among individuals in Canada. A database of COVID-19 literature established at the Public Health Agency of Canada was searched for articles referencing vaccination and knowledge, attitudes and behaviours towards COVID-19 boosters. A grey literature search of Canadian governmental and academic institutions was also conducted. Primary research conducted in Canada (n=21) and relevant systematic reviews of the global literature (n=8) were included in this evidence brief. Intentions to get a booster dose in the general population have decreased between 2021-2023, with intentions varying across subpopulations. In Canada and within the global systematic reviews, facilitators, barriers and hesitancy were similar. Older age was the most common factor positively associated with intention/uptake of a booster, and the most common motivators were government/healthcare provider recommendations and helping to protect others. The main reasons for hesitancy were concerns about vaccine side effects and a lack of belief in the vaccine's efficacy. Intentions to get a booster dose have decreased in Canada. Understanding the reasons for vaccine hesitancy and motivators for obtaining a booster can help guide future public health COVID-19 booster vaccination programs.

Investigating Covid-19 Vaccine Booster Dose Policy Acceptance among Pregnant Women

Investigating Covid-19 Vaccine Booster Dose Policy Acceptance among Pregnant Women

Acceptance of COVID-19 vaccine booster doses among the Adult Population in Ghana: a cross-sectional study using the Health Belief Model.

The Health Belief Model (HBM) is a widely utilised framework for understanding vaccination behaviour against COVID-19. This study assessed the acceptance of COVID-19 vaccine booster doses in Ghana and identified predictors using HBM domains, including perceived susceptibility, severity, benefits, barriers, self-efficacy, and cues to action. Additionally, it examined the sources of information about COVID-19 vaccines. We employed a cross-sectional quantitative design, using convenient and snowball sampling methods to recruit participants. Between March 20 and May 10, 2023, 822 Ghanaians completed a predesigned self-administered online survey via commonly used social media platforms (WhatsApp, Facebook, X (Twitter), and LinkedIn). The study used a binary logistic regression to predict COVID-19 booster dose acceptance. The respondents had a mean age of 29.3 ± 6.2, with 55.5 being males, 53.0% being single/never married, 93.7% having tertiary education, 83.0% being Christians, 59.1% were healthcare workers, 57.8% residing in urban areas, 95.5% having no chronic disease, 90.6% reporting negative COVID-19 history, and 78.3% reporting no reported relative/friend infected with COVID-19. The study showed that 81.1% [95% confidence interval (CI) = 78.4 - 83.8%] of respondents received the COVID-19 vaccine, and 58.3% [95% CI = 54.2 - 62.5%] of respondents were willing to accept the COVID-19 booster dose. The main reasons for non-acceptance of COVID-19 vaccine booster doses were personal reasons (41.7%) and experienced side effects or fear of side effects (32.4%). Regression analysis revealed that perceived benefits and perceived barriers (specifically worrying about serious risk factors) were the significant predictors of accepting COVID-19 booster doses in Ghana. Many respondents were willing to receive the COVID-19 booster dose. Personal reasons, fear of side effects, and experienced side effects were the main reasons for refusing COVID-19 booster doses. Perceived benefits and perceived barriers predicted COVID-19 booster dose acceptance in Ghana. Policymakers should consider these factors in designing public health interventions to increase the patronage of COVID-19 booster doses.

Three doses of Sars-CoV-2 mRNA vaccine in older adults result in similar antibody responses but reduced cellular cytokine responses relative to younger adults

ObjectivesBooster COVID-19 vaccinations are used to protect the elderly, a group vulnerable to severe disease. We compared humoral and cellular immunity in older versus younger adults up to eight months after administering a BNT16b2 booster vaccine dose. Next, we analyzed the plasma levels of soluble T cell activation/exhaustion markers. MethodsHome-dwelling older adults (n = 68, median age 86) and younger healthcare workers (n = 35, median age 39), previously vaccinated with two doses of BNT162b2, were given a booster dose at ten months after the initial dose. Our analysis consisted of spike-specific IgG, neutralizing antibodies, memory B cells, IFN-γ and IL-2 secreting T cells and soluble T cell exhaustion/activation markers. ResultsFollowing the initial two doses, the elderly cohort exhibited lower humoral and IFN-γ responses compared to younger adults. The booster dose increased the humoral responses in both older and younger adults. At two months after the booster dose, older and younger vaccinees had comparable levels of antibodies and the responses were maintained up to 18 months. The younger cohort elicited an increase in the cellular response, while no increase was detected in the elderly. The elderly had higher plasma levels of soluble forms of the T cell activation/exhaustion markers CD25 and TIM-3, which inversely correlated with age and T-cell cytokine responses. This suggests that these markers may be related to the observed dysfunctional cellular cytokine response in older adults. However, both elderly and younger adults who experienced breakthrough infections after booster vaccination, elicited more robust humoral and IFN-γ responses. ConclusionsThe booster dose elicited neutralizing and spike-specific antibody responses in the elderly that were comparable with that of the younger cohort. However, the lack of a strong cellular cytokine response to the third dose in the elderly may explain their vulnerability to severe infection and may be a consequence of exhausted or senescent T cell responses. (https://clinicaltrials.gov/study/NCT04706390).