Factors influencing the third COVID-19 vaccine booster dose acceptance among older adults in northern Thailand.

BACKGROUND: Coronavirus disease 2019 (COVID-19) causes more deaths in older adults than in younger adults. Older adults are a vulnerable group with a high need for coronavirus vaccines to decrease the severity of the disease. The aim of this analytical cross-sectional study was to determine the factors influencing third COVID-19 vaccine booster dose acceptance among older adults in northern Thailand. METHODS: The study samples were composed of 2,155 older adults living in Kamphaeng Phet Province, northern Thailand. They were randomly selected by multistage random sampling. Data were collected in a self-administered questionnaire consisting of 7 parts: (1) personal factors, (2) knowledge about COVID-19, (3) perceived susceptibility to COVID-19 infection, (4) perceived severity of COVID-19, (5) perceived benefits of the third COVID-19 vaccine booster dose, (6) perceived barriers to the third COVID-19 vaccine booster dose vaccination, and (7) the third COVID-19 vaccine booster dose acceptance. Data were analyzed via frequency, percentage, mean, standard deviation, and binary logistic regression. All the significance levels were set to 0.05. RESULTS: The results indicated that only 28.5% of older adults accepted the third COVID-19 vaccine booster dose. The factors influencing third COVID-19 vaccine booster dose acceptance among older adults included 5 variables. The participants aged ≥ 70 years was 1.37 times (95%CI = 1.12-1.69) greater than those aged < 70 years who accepted the vaccine. Participants who were married were more likely to accept the vaccine by 1.39 times (95%CI = 1.09-1.79) compared with single individuals. Those with underlying diseases tended to accept the vaccine by 1.56 times (95%CI = 1.26-1.92) more than those without underlying diseases. Those who had high perceived benefit from the COVID-19 vaccine possibly accepted the vaccine by 1.50 times (95%CI = 1.10-2.04) more than those with low perceived benefit, and those who had a low perceived barrier to the third COVID-19 booster dose vaccination seemed to accept the vaccine by 1.29 times (95%CI = 1.01-1.52) more than those with a high perceived benefit. CONCLUSION: Older adults should receive health education regarding the perceived benefit of the COVID-19 vaccine and the perceived barrier to COVID-19 vaccination, especially older adults aged < 70 years, those who are single, and those who are free of underlying diseases.

Immunogenicity and safety of different combinations involving a third booster dose of SARS-CoV-2 inactivated vaccine, inactivated quadrivalent influenza vaccine, and 23-valent pneumococcal polysaccharide vaccine in adults aged ≥60 years: a phase 4, randomized, open-label study.

Background: Concomitant administration of COVID-19, influenza, and pneumococcal vaccines could reduce the burden on healthcare systems. However, the immunogenicity and safety of various combinations of a third booster dose of SARS-CoV-2 inactivated vaccine (CoronaVac), inactivated quadrivalent influenza vaccine (IIV4), and 23-valent pneumococcal polysaccharide vaccine (PPV23), particularly in different age groups, is still unknown. Methods: A phase 4, randomized, open-label, controlled trial was conducted in Beijing, China. 636 healthy adults were divided into two age groups (18-59 and ≥60 years) and randomized equally into three groups: CoronaVac and IIV4 followed by PPV23; CoronaVac and PPV23 followed by IIV4; or CoronaVac followed by IIV4 and PPV23, with a 28-day interval between vaccinations. Immunogenicity was evaluated by measuring antibody titers, and safety was monitored. ClinicalTrials.gov Identifier: NCT05298800. Results: Co-administration of a third dose of CoronaVac, IIV4, and PPV23 in any combination was safe. Among adults aged 18-59, co-administration with PPV23 maintained non-inferiority of antibody levels for CoronaVac and IIV4, despite a slight reduction in antibody responses. This reduction was not observed in participants ≥60 years. Furthermore, co-administration of IIV4 and PPV23 affected seroconversion rates for both vaccines. Conclusions: Co-administration of the third dose of SARS-CoV-2 inactivated vaccine with the influenza vaccine, followed by PPV23, may be optimal for adults aged 18-59. In adults ≥60, all vaccine combinations were immunogenic, suggesting a flexible vaccination approach. Since antibody measurements were taken 28 days post-vaccination, ongoing surveillance is essential to assess the longevity of the immune responses.

Safety and antibody responses of Omicron BA.4/5 bivalent booster vaccine among hybrid immunity with diverse vaccination histories: A cohort study.

This cohort study, conducted between July and August 2023, evaluated the adverse events (AEs) and immune response to a bivalent mRNA-1273.222 (containing sequences of the original Wuhan-H1 strain and the Omicron BA.4/5 variant) booster vaccine in 122 participants. The study included individuals with diverse vaccination histories, and their responses were assessed based on anti-receptor binding domain (RBD) IgG levels and neutralizing antibodies against the wild-type, Omicron BA.5, and XBB.1.16 variants. Following administration of the BA.4/5 bivalent vaccine, AEs were generally mild to moderate and well-tolerated within a few days. There were no reports of vomiting and no serious AEs or death. The findings demonstrated robust immune responses, with significant increases in anti-RBD IgG levels, particularly in groups that had received 3 -6 doses before the booster dose. The BA.4/5 bivalent booster effectively induced neutralizing antibodies against the vaccine strains, providing robust neutralization, including the XBB.1.16 strain. The study also highlighted that individuals with hybrid immunity, especially those assumed infected with the BA.5 strain or who had been infected twice, showed higher levels of robust neutralizing activity against Omicron XBB.1.16. Overall, these results indicate that the BA.4/5 bivalent booster vaccines can induce potent and good antibody responses in emerging Omicron subvariants, supporting its efficacy as a booster in individuals with diverse vaccination histories.

Safety and Immunogenicity of an mRNA-1273 Booster in Children.

BACKGROUND: A 2-dose mRNA-1273 primary series in children aged 6 months-5 years (25-µg) and 6-11 years (50-µg) had an acceptable safety profile and was immunogenic in the phase 2/3 KidCOVE study. We present data from KidCOVE participants who received an mRNA-1273 booster dose. METHODS: An mRNA-1273 booster dose (10-µg for children aged 6 months-5 years; 25-µg for children aged 6-11 years; age groups based on participant age at enrollment) was administered ≥6 months after primary series completion. The primary safety objective was the safety and reactogenicity of an mRNA-1273 booster dose. The primary immunogenicity objective was to infer efficacy of an mRNA-1273 booster dose by establishing noninferiority of neutralizing antibody (nAb) responses after a booster in children compared with nAb responses observed after the mRNA-1273 primary series in young adults (18-25 years) from the pivotal efficacy study. Data were collected from March 2022 to June 2023. RESULTS: Overall, 153 (6 months-5 years) and 2519 (6-11 years) participants received an mRNA-1273 booster dose (median age at receipt of booster: 2 and 10 years, respectively). The booster dose safety profile was generally consistent with that of the primary series in children; no new safety concerns were identified. An mRNA-1273 booster dose elicited robust nAb responses against ancestral SARS-CoV-2 among children and met prespecified noninferiority success criteria when compared with responses observed after the primary series in young adults. CONCLUSIONS: Safety and immunogenicity data support administration of a mRNA-1273 booster dose in children aged 6 months to 11 years. CLINICAL TRIALS REGISTRATION: NCT04796896.

Primary Healthcare Providers' Views on Periodic COVID-19 Booster Vaccination for Themselves and Their Patients: A 2023 Nationwide Survey in Belgium.

New COVID-19 strains and waning vaccine effectiveness prompted initiatives for booster vaccination. In Belgium, healthcare providers (HCPs) received a second booster in July 2022, with eligible individuals receiving a third in autumn. Primary HCPs (PHCPs) play a crucial role in healthcare organization and patient communication. This study, conducted in February-March 2023, surveyed 1900 Belgian PHCPs to assess their views on periodic COVID-19 boosters for themselves and their patients. The survey included questions on sociodemographic information, willingness to receive periodic COVID-19 boosters, reasons for acceptance or refusal, confidence in vaccine safety and efficacy, and views on booster recommendations. Overall, 86% of participants were willing to receive periodic COVID-19 boosters, motivated by self-protection, patient well-being, and the uninterrupted delivery of healthcare services. Factors influencing booster refusal included not being a general practitioner (GP) or GP trainee, working in Wallonia or Brussels, and lacking vaccine confidence. Although 243 participants would not take boosters periodically, only 74 would not recommend it. Regarding administration, 59% supported pharmacist involvement in COVID-19 vaccination. Further qualitative analysis of 290 PHCPs' responses revealed varying recommendations, including specific roles like nurses, organizational structures, and collaborative approaches. This study highlights the need to address vaccine confidence, regional disparities, and PHCP roles in booster implementation.

Breakthrough COVID-19 Infections after Booster SARS-CoV-2 Vaccination in a Greek Cohort of People Living with HIV during the Delta and Omicron Waves.

INTRODUCTION: Currently approved SARS-CoV-2 vaccines have been proven effective in protecting against severe COVID-19; however, they show variable efficacy against symptomatic infection and disease transmission. We studied the breakthrough COVID-19 infection (BTI) after booster vaccination against SARS-CoV-2 in people living with HIV (PWH). METHODS: This was a retrospective, single-center, descriptive cohort study involving PWH, who were followed in the HIV Clinic of "Attikon" University Hospital in Athens, Greece. A BTI was defined as a case of laboratory-confirmed COVID-19 occurring at least 14 days after the third (booster) vaccine dose. RESULTS: We studied 733 PWH [males: 89%, mean age: 45.2 ± 11.3 years, mean BMI: 26.1 ± 4.1, HIV stage at diagnosis (CDC classification): A/B/C = 80/9/11%, MSM: 72.6%] with well-controlled HIV infection. At least one comorbidity was recorded in 54% of cases. A history of ≥1 vaccination was reported by 90%, with 75% having been vaccinated with ≥3 vaccines. Four hundred and two (55%) PWH had a history of COVID-19 and 302 (41.2%) had a BTI, with only 15 (3.7%) needing hospitalization. Only one patient was admitted to the ICU, and no death was reported. Regarding BTI after booster dose, increased age (OR = 0.97, 95% CI: 0.96-0.99, per 1-year increase), and COVID-19 infection prior to booster dose (OR = 0.38, 95% CI: 0.21-0.68) were associated with a lower likelihood for BTI, whereas higher BMI (OR = 1.04, 95% CI: 1.01-1.08) and MSM as a mode of HIV transmission were associated with increased risk (OR = 2.59, 95% CI: 1.47-4.56). The incidence rate of total COVID-19 and BTI followed the epidemic curve of the general population, with the highest incidence recorded in June 2022. CONCLUSIONS: A significant proportion of PWH with well-controlled HIV infection experienced a BTI, with the majority of them having mild infection. These data, which include the period of Omicron variant predominance, confirm the importance of vaccination in the protection against severe COVID-19.

The immunologic outcomes and adverse events of COVID-19 vaccine booster dose in immunosuppressed people: A systematic review.

Introduction: This study examines the efficacy and safety of three COVID-19 booster vaccines including mRNA-based vaccines (BNT162b2 (BioNTech/Pfizer) and/or mRNA-1273 (Moderna)), Non-Replicating Viral-Vector vaccines (ChAdOx1 nCoV-19 vaccine (AstraZeneca) and/or Ad26. COV2.S (Johnson & Johnson)), and Protein Subunit vaccine (SpikoGen) in immunosuppressed patients. Methods: Relevant articles were systematically searched using medical subject heading (MeSH) and keywords "COVID-19" and "booster dose" or "booster vaccine" or ''fourth dose" in the online databases of PubMed, Embase, Scopus, and Web of Science. To identify eligible studies, a two-phase screening process was implemented. Initially, three researchers evaluated the studies based on the relevancy of the title and abstract. Results: A total of 58 studies met the inclusion criteria and were included in this review. The findings suggest that booster doses offer greater protection against the disease than the primary dose. The study also compared various vaccine types, revealing that viral vector and nucleic acid vaccines outperformed inactivated vaccines. Results indicated that individuals receiving booster doses experienced superior outcomes compared to those without boosters. Vaccination against COVID-19 emerged as the most effective preventive measure against infection and symptom severity. Elevated antibody levels post-booster dose vaccination in the population signaled robust immune responses, underscoring the benefits of supplementary vaccine doses. Conclusion: This systematic review highlights preliminary evidence supporting the immunologic outcomes and safety of COVID-19 vaccine boosters in enhancing immune responses against SARS-CoV-2. However, further research is needed to determine optimal timing intervals between primary vaccination series and boosters while considering global equity issues and variant-specific considerations.

Duration of vaccine protection against breakthrough infections during five COVID-19 waves among healthcare workers primarily vaccinated with CoronaVac.

We aimed to characterise vaccine-induced protection against COVID-19 during five waves caused by Variants of Concern (VOCs). This is a nested case-control study of 3,972 HCW primarily vaccinated with CoronaVac (98%) that evaluated symptomatic SARS-CoV-2 breakthrough infections (BI) in almost two-years follow-up until the 3rd Omicron wave. Predictors of protection against SARS-CoV-2 BI were analysed using conditional logistic regression models. We included 1,491 SARS-CoV-2 breakthrough cases, mostly mild, and 2,962 controls. Most participants (90%) had received at least one booster before the onset of the Omicron waves, mainly BNT162b2. A multivariate logistic regression showed that vaccine-induced protection against BI wanes after six months regardless of the number of monovalent booster doses. Additionally, booster dose with BNT162b2 showed a trend for higher protection compared to CoronaVac during the Omicron waves. In conclusion, immunity of monovalent booster doses against SARS-CoV-2 is short-lasting. Individuals previously vaccinated with an inactivated vaccine should receive a BNT162B2 booster dose.

Incobotulinum Toxin-A in Professional Musicians with Focal Task-Specific Dystonia: A Double Blind, Placebo Controlled, Cross-Over Study.

Background: Musician's focal task-specific dystonia is a complex disorder of fine motor control, with incomplete understanding of its etiology. There have been relatively few trials of botulinum toxin in upper limb task-specific dystonia, and prior studies have yielded variable results, leading to skepticism regarding the utility of this approach in elite performers. Methods: We conducted a double-blind, placebo-controlled, randomized, cross-over study of incobotulinum toxin-A in 21 professional musicians with focal upper extremity task-specific dystonia affecting performance on their instrument, using a novel paradigm of initial injections followed by booster injections at two- and four-week intervals. The primary outcome measure was the change in blinded dystonia rating of the active arm by two expert raters using a Clinical Global Impression numeric scale at week 8 compared to enrollment. Findings: 19 men and 2 women with musicians' dystonia were enrolled over a six-year period. Nineteen patients completed the study. Analysis of the primary outcome measure in comparison to baseline revealed a change in dystonia severity of P = 0.04 and an improvement in overall musical performance of P = 0.027. No clinically significant weakness was observed, and neutralizing antibodies to toxin were not found. Interpretation: Despite its small sample size, our study demonstrated a statistically significant benefit of incobotulinum toxin-A injections as a treatment for musicians' task-specific dystonia. Tailoring the use of toxin with booster injections allowed refinement of dosing strategy and outcomes, with benefits that were meaningful to patients clearly visible on videotaped evaluations. In addition to its application to musicians' dystonia, this approach may have relevance to optimize application of botulinum toxin in other forms of focal dystonia such as blepharospasm, cervical dystonia, writer's cramp, and spasmodic dysphonia.

Immunogenicity during 6 months after SARS-CoV-2 infection is significantly different depending on previous COVID-19 vaccine regimens and a booster dose received.

Data on immunogenicity induced by SARS-CoV-2 infection and its sustainability are essential to inform COVID-19 vaccine schedule. A prospective cohort study was conducted among adults at-risk for COVID-19 during the Omicron variant-dominant epidemic. All were followed up for anti-spike RBD levels on days 0, 14, 90 and 180 after enrollment. Of the 871 individuals included, 264 (30.3 %) had COVID-19. Those with COVID-19 had significantly lower baseline geometric mean level of anti-spike RBD than those without COVID-19 (326 vs. 989; P < 0.001). Among the COVID-19 patients, anti-spike RBD level significantly increased the most at 14 days after infection and dropped significantly at day 90 and day 180. Giving a booster dose during 91-180 days after infection induced high level of anti-spike RBD through 180 days. These findings suggest high level but short-lived immunity induced by SARS-CoV-2 infection while sustained immunity required a booster dose administered from 90 days after the infection.

Factors Influencing COVID-19 Vaccination among Primary Healthcare Nurses in the Pandemic and Post-Pandemic Period: Cross-Sectional Study.

The decision to vaccinate against COVID-19 is primarily a personal choice influenced by numerous factors. Vaccine acceptance and a positive attitude towards vaccination among nurses have an impact on patients' willingness to vaccinate. To assess COVID-19 vaccination coverage among primary healthcare nurses and to associate socio-demographic factors, comorbidity, self-rated health, and unhealthy lifestyle with the decision to be vaccinated, we conducted an online cross-sectional study from March to May 2023 using a self-administrated questionnaire. Probability sampling was used to select 32 health centers and nurses were invited via email. Among the 560 participants who completed survey, 78.3% and 50.8% received the primary two-dose course and at least one booster dose of COVID-19 vaccine, respectively. Primary care nurses who were ≥41 years of age, physically less active, and those who were overweight opted statistically significantly more often for the primary vaccination scheme (p = 0.00, 0.015 and 0.017, respectively). Education and the living environments of primary care nurses did not significantly influence the decision to receive two primary COVID-19 doses. Likewise, good self-rated health and comorbidity did not contribute significantly to the vaccination decision. Nurses that were vaccinated with booster doses were significantly more often overweight (p = 0.034) and ≥41 year of age (p = 0.000).

Efficacy, safety, and immunogenicity of SARS-CoV-2 mRNA vaccine (Omicron BA.5) LVRNA012: a randomized, double-blind, placebo-controlled phase 3 trial.

Background: We aimed to evaluate the efficacy, safety, and immunogenicity of a SARS-CoV-2 mRNA vaccine (Omicron BA.5) LVRNA012 given as the booster in immunized but SARS-CoV-2 infection-free adults in China. Methods: This is a single-center, randomized, double-blind, placebo-controlled phase 3 clinical trial enrolling healthy adult participants (≥18 years) who had completed two or three doses of inactivated COVID-19 vaccines at least 6 months before, in Bengbu, Anhui province, China. Eligible participants were randomly assigned (1:1) to receive a booster intramuscular vaccination with an LVRNA012 vaccine (100ug) or placebo. The primary endpoint was the protective efficacy of a booster dose of the LVRNA012 vaccine or placebo against symptomatic COVID-19 of any severity 14 days after vaccination. Laboratory-confirmed COVID-19 infections were identified from 14 days to 180 days after intervention, with active surveillance for symptomatic illness 8 times per month between 7 to 90 days and at least once per month between 90 to 180 days after intervention. Results: 2615 participants were recruited and randomly assigned in a 1:1 ratio to either the vaccine group (1308) or the placebo group (1307). A total of 141 individuals (46 in the LVRNA012 group and 95 in the placebo group) developed symptomatic COVID-19 infection 14 days after the booster immunization, showing a vaccine efficacy of 51.9% (95% CI, 31.3% to 66.4%). Most infections were detected 90 days after intervention during a period when XBB was prevalent in the community. Adverse reactions were reported by 64% of participants after the LVRNA012 vaccination, but most of them were mild or moderate. The booster vaccination with the LVRNA012 mRNA vaccine could significantly enhance neutralizing antibody titers against the Omicron variant XBB.1.5 (GMT 132.3 [99.8, 175.4]) than did those in the placebo group (GMT 12.5 [8.4, 18.7]) at day 14 for the previously immunized individuals. Conclusion: The LVRNA012 mRNA vaccine is immunogenic, and shows robust efficacy in preventing COVID-19 during the omicron-predominate period. Clinical trial registration: ClinicalTrials.gov, identifier NCT05745545.

COVID-19 Booster Vaccination Adverse Effects and Willingness to Receive a Yearly Booster Dose among Members of Health Sciences Faculties: A Descriptive Cross-Sectional Study.

Background: New severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and waning vaccine efficacy led to the administration of booster doses. Healthcare workers (HCWs) are vulnerable to contract the infection, and vaccination hesitancy in this group may have an impact on vaccine uptake among the general public. Aims: This study aimed to (1) assess the prevalence of self-reported adverse effects (AEs) after the first booster dose vaccine, (2) evaluate the AEs between the homologous and heterologous booster vaccines, and (3) evaluate the willingness to receive a hypothetical yearly booster dose. Materials and Methods: An online, cross-sectional, self-administered, structured questionnaire was distributed to members of the health sciences faculties (HSFs), XXXX University, Malaysia. Convenience sampling was adopted, and descriptive statistics was used to interpret the results. Results: About 67.1% of participants experienced systemic or local AEs. The common AEs were pain at the site of injection (60.2%), fatigue (45.7%), headache (31.6%), and fever (24.7%). About 64% of our participants believed that the booster dose provided extra immunity against the coronavirus disease 2019 (COVID-19) infection and 57.7% of participants expressed concern over the "mix-match" of vaccination. About 78% of the participants were keen to receive the hypothetical yearly booster dose. The severity of AEs between the booster dose and the primary dose was statistically insignificant (P < 0.159). Conclusion: Booster vaccination AEs were similar to the primary dose. However, a higher severity of AEs occurring in heterologous vaccine receivers was noted in our study.

Stability and antigenicity of Chlamydia muridarum major outer membrane protein antigen at body temperature.

Chlamydia is an obligate intracellular bacterial pathogen responsible for disease and infertility across multiple species. Currently vaccines are being studied to help reduce the prevalence of this disease. The main advantage of protein subunit vaccines is their high degree of safety although this is traded off with the requirement for multiple booster doses to achieve complete protection. Although in certain populations the booster dose can be difficult and costly to administer, development of delayed vaccine delivery techniques, such as a vaccine capsule, could be the solution to this problem. One of the main drawbacks in this technology is that the antigen must remain stable at body temperature (37 °C) until release is achieved. Here we elucidate the stability of a recombinant chlamydial major outer membrane protein (MOMP) antigen and assess its antigenic and immunogenic properties after subjecting the antigen to 37 °C for four to six weeks. Through in vitro and in vivo assessment we found that the aged chlamydial MOMP was able to produce equivalent humoral and cell-mediated immune responses when compared with the unaged vaccine. It was also found that vaccines formulated with the aged antigen conferred equivalent protection against a live infection challenge as the unaged antigen. Thus ageing chlamydial MOMP antigens at 37 °C for four to six weeks did not cause any significant structural or antigenic/immunogenic degradation and recombinant C. muridarum MOMP is suitable for use in a delayed vaccine delivery system.

Risk factors for COVID-19 hospitalisation after booster vaccination during the Omicron period: A French nationwide cohort study.

BACKGROUND: In spite of major effectiveness, a residual risk after COVID-19 primary vaccination was identified, in particular, for vulnerable individuals of advanced age or with comorbidities. Less is known about the Omicron period in people protected by a booster dose. We aimed to identify the characteristics associated with severe COVID-19 during the Omicron period in a population that had received a booster dose in France and to compare differences with the previous periods of the pandemic. METHODS: This study was carried out using the French national COVID-19 vaccination database (VAC-SI) coupled with the National Health Data System (SNDS). Individuals aged 12 years or over who received at least one booster dose were identified. Associations between socio-demographic and clinical characteristics and the risk of COVID-19 hospitalisation occurring at least 14 days after receiving a third dose of vaccine during the period of Omicron predominance, i.e., from 1 January 2022 to 10 November 2022, were assessed using Cox proportional hazard models adjusted for age, sex, time since booster dose and vaccination schedule. Analyses were performed overall and by sub-period of circulation of the strains BA.1, BA.2, and BA.4/BA.5, defined as periods where the main sub-variant accounted for more than 80 % of genotyped samples. FINDINGS: In total, 35,640,387 individuals received a booster dose (mean follow-up of 291 days) and 73,989 were hospitalised for COVID-19 during the total period. Older age (aHR 20.5 95 % CI [19.6-21.5] for 90 years of age or older versus 45-54 years of age), being male (aHR 1.52 [1.50-1.55]), and social deprivation (aHR 1.33 [1.30-1.37] for the most deprived areas versus the least deprived) were associated with an increased risk of hospitalisation for COVID-19. Most of the chronic diseases considered were also positively associated with a residual risk, in particular, cystic fibrosis (aHR 9.83 [7.68-12.56]), active lung cancer (aHR 3.26 [3.06-3.47]), chronic dialysis (aHR 3.79 [3.49-4.11]), psychological and neurodegenerative diseases (more markedly than during the periods of circulation of the alpha and delta variants), and organ transplantation. The use of immunosuppressants was also associated with an increased risk (aHR 2.24 [2.14-2.35], including oral corticosteroids aHR (2.58 [2.50-2.67]). CONCLUSION: Despite an effective booster and a generally less virulent circulating variant, a residual risk of severe COVID-19 still exists in vulnerable populations, especially those with neurological disorders.

Updated Bivalent COVID-19 Vaccines Reduce Risk of Hospitalization and Severe Outcomes in Adults: An Observational Cohort Study.

Background: This study evaluates the real-world effectiveness of updated bivalent coronavirus disease 2019 (COVID-19) vaccines in adults, as the virus evolves and the need for new vaccinations increases. Methods: In this observational, retrospective, multi-center, cohort analysis, we examined emergency care encounters with COVID-19 in metro Detroit, Michigan, from January 1, 2022, to March 9, 2023. Patients were categorized by vaccination status: unvaccinated, fully vaccinated, fully vaccinated and boosted (FV&B), or fully vaccinated and bivalent boosted (FV&BB). The primary outcome was to assess the impact of bivalent COVID-19 vaccinations on the risk of composite severe outcomes (intensive care unit (ICU) admission, mechanical ventilation, or death) among patients presenting to a hospital with a primary diagnosis of COVID-19. Results: A total of 21,439 encounters met inclusion criteria: 9,630 (44.9%) unvaccinated, 9,223 (43.0%) vaccinated, 2,180 (10.2%) FV&B, and 406 (1.9%) FV&BB. The average age was 48.8, with 59.6% female; 61.1% were White, 32.8% Black, and 6.0% other races. Severe disease affected 5.5% overall: 5.0% unvaccinated, 5.7% vaccinated, 7.0% FV&B, and 4.7% FV&BB (P = 0.001). Severe disease rates among admitted patients were 13.3% unvaccinated, 11.9% vaccinated, 12.2% boosted, and 8.1% FV&BB (P = 0.052). The FV&BB group showed a 4.0% (P = 0.0369) lower risk of severe disease compared to FV&B and a 5.1% (P = 0.0203) lower probability of hospitalization. Conclusions: As the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to mutate and evolve, updated vaccines are necessary to better combat COVID-19. In a real-world hospital-based population, this investigation demonstrates the incremental benefit of the bivalent booster vaccine in reducing the risk of hospitalization and severe outcomes in those diagnosed with COVID-19 compared to all other forms of vaccination.

High Concentration of Anti-SARS-CoV-2 Antibodies 2 Years after COVID-19 Vaccination Stems Not Only from Boosters but Also from Widespread, Often Unrecognized, Contact with the Virus.

This study follows 99 subjects vaccinated with Pfizer/BioNTech COVID-19 vaccines over two years, with particular focus on the last year of observation (between days 360 and 720). The response to the vaccination was assessed with Diasorin's SARS-CoV-2 TrimericSpike IgG. Screening for SARS-CoV-2 infection was performed with Abbott's SARS-CoV-2 Nucleocapsid IgG immunoassay. Data from questionnaires were also analyzed. Two years after the first vaccine dose administration, 100% of the subjects were positive for anti-spike SARS-CoV-2 IgG and the median antibody level was still high (3600 BAU/mL), dropping insignificantly over the last year. Simultaneously, a substantial increase in seropositivity in anti-nucleocapsid SARS-CoV-2 IgG was noted, reaching 33%. There was no statistically significant agreement between anti-N seropositivity and reported COVID-19. Higher anti-spike concentrations and lower COVID-19 incidence was seen in the older vaccinees. It was noted that only subjects boosted between days 360 and 720 showed an increase in anti-spike IgG concentrations. The higher antibody concentrations (median 7440 BAU/mL) on day 360 were noted in participants not infected over the following year. Vaccination, including booster administrations, and natural, even unrecognized, contact with SARS-CoV-2 entwined two years after the primary vaccination, leading to high anti-spike antibody concentrations.

Anti-SARS-CoV-2 Antibodies Level and COVID-19 Vaccine Boosters among Healthcare Workers with the Highest SARS-CoV-2 Infection Risk-Follow Up Study.

During the COVID-19 pandemic, several vaccines were developed to limit the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, due to SARS-CoV-2 mutations and uneven vaccination coverage among populations, a series of COVID-19 waves have been caused by different variants of concern (VOCs). Despite the updated vaccine formulations for the new VOC, the benefits of additional COVID-19 vaccine doses have raised many doubts, even among high-risk groups such as healthcare workers (HCWs). We examined the factors underlying hesitancy to receive COVID-19 booster vaccine doses and analysed the anti-SARS-CoV-2 IgG antibody response after booster vaccination among HCWs. Our study found that 42% of the HCWs were hesitant about the second booster dose, while 7% reported no intent to get vaccinated with any additional doses. As reasons for not vaccinating, participants most frequently highlighted lack of time, negative experiences with previous vaccinations, and immunity conferred by past infections. In addition, we found the lowest post-vaccination antibody titres among HCWs who did not receive any vaccine booster dose and the highest among HCWs vaccinated with two booster doses.

Antibody Response after Homologous and Heterologous Prime-Boost COVID-19 Vaccination in a Bangladeshi Residential University Cohort.

COVID-19 vaccination strategies, including heterologous prime-boost regimens and additional booster doses, aim to optimize immune responses. However, seroepidemiological studies on immune responses to different COVID-19 vaccine types and schedules remain limited. This study investigated antibody levels following homologous and heterologous prime-and-boost COVID-19 vaccination in Bangladesh. In a cohort of 606 participants who received first/second/booster doses of vaccines (AstraZeneca, Moderna, Pfizer-BioNTech, and Sinopharm), anti-spike IgG and anti-nucleocapsid IgG levels were measured. Antibody titer variations with respect to age, gender, intervals between doses, and prior infection status were analyzed. mRNA vaccines elicited the highest antibody levels after homologous and heterologous boosting. The AstraZeneca booster resulted in a sharp titer decline rate of ~0.04 units per day. Second or booster vaccine doses significantly increased antibody levels, especially in males (p < 0.05). Older age correlated with higher titers, likely reflecting previous infection, which was further confirmed by the elevation of anti-nucleocapsid IgG levels. About 95.5% of non-Sinopharm recipients were anti-nucleocapsid IgG positive, suggesting prior exposure exceeding self-reported infections (12.5%). mRNA and heterologous COVID-19 boosting enhances humoral immunity over homologous prime-boost vector/inactivated vaccination. However, waning immunity merits further investigation across vaccine platforms.

Effectiveness of different booster vaccine combinations against SARS-CoV-2 during a six-month follow-up in Mexico and Argentina.

Introduction: Given the limited number of patients in Latin America who have received a booster dose against the COVID-19, it remains crucial to comprehend the effectiveness of different vaccine combinations as boosters in real-world scenarios. This study aimed to assess the real-life efficacy of seven different vaccine schemes against COVID-19, including BNT162b2, ChAdOx1-S, Gam-COVID-Vac, and CoronaVac as primary schemes with either BNT162b2 or ChAdOx1-S as booster vaccines. Methods: In this multicentric longitudinal observational study, participants from Mexico and Argentina were followed for infection and SARS-CoV-2 Spike 1-2 IgG antibodies during their primary vaccination course and for 185 days after the booster dose. Results: A total of 491 patients were included, and the booster dose led to an overall increase in the humoral response for all groups. Patients who received BNT162b2 exhibited the highest antibody levels after the third dose, while those with primary Gam-COVID-Vac maintained a higher level of antibodies after six months. Infection both before vaccination and after the booster dose, and Gam-COVIDVac + BNT162b2 combination correlated with higher antibody titers. Discussion: The sole predictor of infection in the six-month follow-up was a prior COVID-19 infection before the vaccination scheme, which decreased the risk of infection, and all booster vaccine combinations conveyed the same amount of protection.