Cellular and humoral immune responses to COVID-19 booster vaccination in Japanese dialysis patients

BACKGROUND

Dialysis patients are susceptible to developing severe coronavirus disease 2019 (COVID-19) due to hypoimmunity. Antibody titers against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) after the primary vaccinations are lower in hemodialysis (HD) patients than in healthy individuals. This study aimed to evaluate the effect of a SARS-CoV-2 booster vaccination in HD and peritoneal dialysis (PD) patients based on antibody titers and cellular and humoral immunity.

METHODS

Participants of the control, HD, and PD groups were recruited from 12 facilities. SARS-CoV-2 antigen-specific cytokine and IgG-antibody levels were measured. Regulatory T cells and memory B cells were counted using flow cytometry at 6 months after primary vaccination with BNT162b2 and 3 weeks after the booster vaccination in HD and PD patients and compared with those of a control group.

RESULTS

Booster vaccination significantly enhanced the levels of antibodies, cytokines, and memory B cells in three groups. The HD group showed significantly higher levels of IgG-antibodies, IL-1β, IL-2, IL-4, IL-17, and memory B cells than those in the control group at 3 weeks after the booster dose. The PD group tended to show similar trends to HD patients but had similar levels of IgG-antibodies, cytokines, and memory B cells to the control group.

CONCLUSIONS

HD patients had significantly stronger cellular and humoral immune responses than the control 3 weeks after the booster dose. Our findings will help in developing better COVID-19 vaccination strategies for HD and PD patients.

Modelling the Potential Public Health Impact of Different COVID-19 Vaccination Strategies with an Adapted Vaccine in Singapore

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing COVID-19 has been a dynamically changing virus, requiring the development of adapted vaccines. This study estimated the potential public health impact alternative vaccination strategies for COVID-19 in Singapore.

RESEARCH DESIGN AND METHODS

The outcomes of alternative vaccination strategies with a future adapted vaccine were estimated using a combined Markov decision tree model. The population was stratified by high- and standard-risk. Using age-specific inputs informed by local surveillance data and published sources, the model estimated health (case numbers, hospitalizations, and deaths) and economic (medical costs and productivity losses) outcomes in different age and risk subpopulations.

RESULTS

Booster vaccination in only the elderly and high-risk subpopulation was estimated to avert 278,614 cases 21,558 hospitalizations, 239 deaths, Singapore dollars (SGD) 277 million in direct medical costs, and SGD 684 million in indirect medical costs. These benefits increased as vaccination was expanded to other subpopulations. Increasing the booster vaccination coverage to 75% of the standard-risk population averted more deaths (3%), hospitalizations (29%), infections (145%), direct costs (90%), and indirect costs (192%) compared to the base case.

CONCLUSIONS

Broader vaccination strategies using an adapted booster vaccine could have substantial public health and economic impact in Singapore.

Safety and immunogenicity of a booster dose of S-268019-b: Interim findings of a Phase 3, open-label clinical study in Japan

Despite the initial success of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in prevention of symptomatic and severe diseases, booster vaccination has become increasingly important with the advent of variants with immune-escaping capacity. Herein, we report the safety and immunogenicity of S-268019-b, comprising SARS-CoV-2 spike protein and a squalene-based adjuvant, as a booster dose. We performed an interim analysis of an open-label, Phase 3 study data until Day 29 following S-268019-b booster in Japanese adults (aged 20-64 years) who had completed primary vaccination with mRNA-1273 and in Japanese elderly (aged ≥ 65 years) who had completed primary vaccination with mRNA-1273 or BNT162b2. Reactogenicity was mild in most participants; no serious treatment-related adverse events were noted. S-268019-b enhanced SARS-CoV-2 neutralizing antibodies, immunoglobulin G antibodies, and predominant T-helper 1-mediated immune reaction in all cohorts, regardless of age, in Japanese participants with prior vaccination with mRNA vaccines.

Assessing the potential impact of COVID-19 booster doses and oral antivirals: A mathematical modelling study of selected middle-income countries in the Indo-Pacific

Continued efforts to reduce the burden of COVID-19 require the consideration of additional booster doses and emerging oral antivirals. This study explored the individual- and population-level impacts of booster dose and oral antivirals in Indonesia, Fiji, Papua New Guinea, and Timor-Leste. Our mathematical model included age structure, vaccine coverage, prevalence of comorbidities, and immunity from prior infection fit to incidence data from our study settings. We explored a range of eligibility criteria and found that boosters had the largest impact per dose when prioritised to high-risk adults and adults who had not previously received a booster. Antivirals were most effective in settings with low vaccine-derived immunity. In general, fewer antivirals than booster doses were required to prevent a hospitalisation or death. Only in settings with very high vaccine uptake was the impact per dose of providing booster doses to high-risk adults comparable to providing oral antivirals to high-risk adults. Together, booster doses and oral antivirals could prevent 80%, 64%, 49%, and 65% of deaths, and 38%, 37%, 16%, and 34% of hospitalisations in Fiji, Indonesia, Papua New Guinea, and Timor-Leste respectively. Therefore, our findings support the continued provision of COVID-19 booster doses to high-risk adults in 2023, and advocate for increased access to oral antivirals, especially in settings with low vaccine coverage such as Papua New Guinea. Future work should consider the threshold at which self-financing of COVID-19 oral antivirals would be viable for middle-income countries in South-East Asia and the Pacific.

Comparison of immune response to SARS-COV-2 vaccine in COVID-recovered versus non-infected Individuals

To determine the antibody levels at 6 months in SARS-CoV-2 vaccinated individuals in COVID-recovered versus non-infected groups to determine the need to administer booster COVID vaccine in each group. Prospective longitudinal study. Pathology Department, Combined Military Hospital, Lahore for a period of eight months from July 2021 to February 2022. Two hundred and thirty three study participants in both COVID recovered and non-infected groups (105 participants in infected group, 128 participants in non-infected group) were subjected to blood sampling at 6 months post-vaccination. Anti-SARS-CoV-2 IgG antibody test was done using Chemiluminescence method. Comparison of antibody levels between COVID-recovered and non-infected groups was made. Results were compiled and statistically analyzed using SPSS version 21. Out of 233 study participants, males were 183 (78%) while females were 50 (22%), mean age being 35.93 years ± 8.298. Mean Anti-SARS-CoV-2 S IgG levels among COVID-recovered group was 1342 U/ml and among non-infected group was 828 U/ml at 6 months post-vaccination. Mean antibody titers in COVID-19 recovered group are higher than in non-infected group at 6 months post-vaccination in both groups.

Impact of a dTcaP booster vaccine awareness campaign initiated by the French national health insurance for adults aged 25 years in 2021

BACKGROUND

Vaccination schedules differ from country to country. In France, the diphtheria, tetanus, pertussis, poliomyelitis (dTcaP) booster vaccine coverage for adults aged 25 has been lower than those recommended. We evaluated the impact of an awareness campaign undertaken by the French national health insurance system in 2021.

METHODS

A randomized, controlled study with adults residing in the Ardennes region was conducted to evaluate the effect on vaccine coverage of the booster vaccine reminder campaign carried out via letter and/or email and/or SMS. The randomization unit was the municipal administrative area (canton). Ten cantons were grouped into the intervention group (INT) and nine were the control group (CON). Outcomes were the booster vaccine delivery and the consultation of a general practitioner (GP) within 12 months (since the French national health insurance running the campaign suggested patients to consult their GP).

RESULTS

A total of 1,975 adults were included (INT: 67.3% vs. CON: 32.7%). Of them, 331 received a booster vaccine (INT: 17.4% vs. CON: 15.5%; p = 0.29), and 1,442 consulted a GP (INT: 73.7% vs. CON: 76.8%; p = 0.14). Those who consulted a GP had more frequent vaccine delivery (INT: 19.1% vs. CON: 10.5%; p < 0.0001).

CONCLUSIONS

This study found that the awareness campaign run by the French national health insurance did not improve the uptake of the dTcaP booster and that there was a low rate of vaccinated adults aged 25 years. A GP consultation was associated with dTcaP booster vaccine delivery which may show that there is a need of involving GPs in vaccination follow-ups. Patients recognize GPs as providers of credible information and they may play a key role in individualized preventive healthcare actions. Systematic consultations with GPs for follow-up could be proposed to insured adults aged 25 years in the future.

Impact of COVID-19 and effects of booster vaccination with BNT162b2 on six-month long COVID symptoms, quality of life, work productivity and activity impairment during Omicron

BACKGROUND

Longitudinal estimates of long COVID burden during Omicron remain limited. This study characterized long-term impacts of COVID-19 and booster vaccination on symptoms, Health-Related Quality of Life (HRQoL), and Work Productivity Activity Impairment (WPAI).

METHODS

Outpatients with ≥ 1 self-reported symptom and positive SARS-CoV-2 test at CVS Health United States test sites were recruited between 01/31 and 04/30/2022. Symptoms, EQ-5D and WPAI were collected via online surveys until 6 months following infection. Both observed and model-based estimates were analyzed. Effect sizes based on Cohen's d quantified the magnitude of outcome changes over time, within and between vaccination groups. Mixed models for repeated measures were conducted for multivariable analyses, adjusting for covariates. Logistic regression assessed odds ratio (OR) of long COVID between vaccination groups.

RESULTS

At long COVID start (Week 4), 328 participants included 87 (27%) Boosted with BNT162b2, 86 (26%) with a BNT162b2 primary series (Primed), and 155 (47%) Unvaccinated. Mean age was 42.0 years, 73.8% were female, 26.5% had ≥ 1 comorbidity, 36.9% prior infection, and 39.6% reported ≥ 3 symptoms (mean: 3.1 symptoms). At Month 6, among 260 participants, Boosted reported a mean of 1.1 symptoms versus 3.4 and 2.8 in Unvaccinated and Primed, respectively (p < 0.001). Boosted had reduced risks of ≥ 3 symptoms versus Unvaccinated (observed: OR 0.22, 95% CI 0.10-0.47, p < 0.001; model-based: OR 0.36, 95% CI 0.15-0.87, p = 0.019) and Primed (observed: OR 0.29, 95% CI 0.13-0.67, p = 0.003; model-based: OR 0.59, 95% CI 0.21-1.65, p = 0.459). Results were consistent using ≥ 2 symptoms. Regarding HRQoL, among those with long COVID, Boosted had higher EQ-5D Utility Index (UI) than Unvaccinated (observed: 0.922 vs. 0.731, p = 0.014; model-based: 0.910 vs. 0.758, p-value = 0.038) and Primed (0.922 vs. 0.648, p = 0.014; model-based: 0.910 vs. 0.708, p-value = 0.008). Observed and model-based estimates for EQ-VAS and UI among Boosted were comparable with pre-COVID since Month 3. Subjects vaccinated generally reported better WPAI scores.

CONCLUSIONS

Long COVID negatively impacted HRQoL and WPAI. The BNT162b2 booster could have a beneficial effect in reducing the risk and burden of long COVID. Boosted participants reported fewer and less durable symptoms, which contributed to improve HRQoL and maintain WPAI levels. Limitations included self-reported data and small sample size for WPAI.

Spontaneously reported adverse events following COVID-19 basic and booster immunizations in the Netherlands

INTRODUCTION

The rapid roll-out of novel COVID-19 vaccines made near real-time post-marketing safety surveillance essential to identify rare and long-term adverse events following immunization (AEFIs). In light of the ongoing booster vaccination campaigns, it is key to monitor changes in observed safety patterns post-vaccination. The effect of sequential COVID-19 vaccinations, as well as heterologous vaccination sequences, on the observed post-vaccination safety pattern, remains largely unknown.

METHODS

The primary objective of this study was to describe the profile of spontaneously reported AEFIs following COVID-19 vaccination in the Netherlands, including the primary and booster series. Reports from consumers and healthcare professionals were collected via a COVID-19 vaccine-tailored online reporting form by the National Pharmacovigilance Centre Lareb (Lareb) between 6 January 2021 and 31 August 2022. The data were used to describe the most frequently reported AEFIs per vaccination moment, the consumer experienced burden per AEFI, and differences in AEFIs reported for homologous and heterologous vaccination sequences.

RESULTS

Lareb received 227,884 spontaneous reports over a period of twenty months. Overall, a high degree of similarity in local and systemic AEFIs per vaccination moment was observed, with no apparent change in the number of reports of serious adverse events after multiple COVID-19 vaccinations. No differences in the pattern of reported AEFIs per vaccination sequence was observed.

CONCLUSION

Spontaneous reported AEFIs demonstrated a similar reporting pattern for homologous and heterologous primary and booster series of COVID-19 vaccination in the Netherlands.

Levels and durability of neutralizing antibodies against SARS-CoV-2 Omicron and other variants after ChAdOx-1 or BNT162b2 booster in CoronaVac-primed elderly individuals

The outbreak of the SARS-CoV-2 Omicron variant raised the need for vaccine boosting. We evaluated the efficiency of the third booster vaccine, ChAdOx-1 or BNT162b2, in causing a neutralizing antibody (NAb) response and its durability against the Omicron and other variants in elderly individuals previously vaccinated with 2-dose CoronaVac inactivated vaccine. After receiving 2-dose CoronaVac, only 2.2% of subjects had NAbs against the Omicron variant above the cut-off value. Four weeks after boosting, the number of subjects who had NAb levels above the cut-off values in the ChAdOx-1 and BNT162b2 vaccine boosting groups increased to 41.7% and 54.5%, respectively. However, after 12 and 24 weeks of boosting with any vaccines, NAb levels against the Omicron variant dramatically waned. Twenty-four weeks after boosting, only 2% had high levels of NAbs against the Omicron variant. Compared to other variants, the Omicron variant was less responsive to boosting vaccines. The waning rate of NAb levels for the Omicron variant was much faster than that observed in the Alpha, Beta and Delta variants. To combat the Omicron variant, the fourth booster dose is, therefore, recommended for elderly individuals.

Coverage of primary and booster vaccination against COVID-19 by socioeconomic level: A nationwide cross-sectional registry study

High and equitable COVID-19 vaccination coverage is important for pandemic control and prevention of health inequity. However, little is known about socioeconomic correlates of booster vaccination coverage. In this cross-sectional study of all Norwegian adults in the national vaccination program (N = 4,190,655), we use individual-level registry data to examine coverage by levels of household income and education of primary (≥2 doses) and booster (≥3 doses) vaccination against COVID-19. We stratify the analyses by age groups with different booster recommendations and report relative risk ratios (RR) for vaccination by 25 August 2022. In the 18-44 y group, individuals with highest vs. lowest education had 94% vs. 79% primary coverage (adjusted RR (adjRR) 1.15, 95%CI 1.14-1.15) and 67% vs. 38% booster coverage (adjRR 1.55, 95% CI 1.55-1.56), while individuals with highest vs. lowest income had 94% vs. 81% primary coverage (adjRR 1.10, 95%CI 1.10-1.10) and 60% vs. 43% booster coverage (adjRR 1.23, 95%CI 1.22-1.24). In the ≥45 y group, individuals with highest vs. lowest education had 96% vs. 92% primary coverage (adjRR 1.02, 95%CI 1.02-1.02) and 88% vs. 80% booster coverage (adjRR 1.09, 95%CI 1.09-1.09), while individuals with highest vs. lowest income had 98% vs. 82% primary coverage (adjRR 1.16, 95%CI 1.16-1.16) and 92% vs. 64% booster coverage (adjRR 1.33, 95%CI 1.33-1.34). In conclusion, we document large socioeconomic inequalities in COVID-19 vaccination coverage, especially for booster vaccination, even though all vaccination was free-of-charge. The results highlight the need to tailor information and to target underserved groups for booster vaccination.

Safety and immunogenicity of inactive vaccines as booster doses for COVID-19 in Türkiye: A randomized trial

Protective neutralizing antibody titers reduce in time after COVID-19 vaccinations, as in individuals who have had COVID-19. This study aimed to evaluate the safety and immunogenicity of CoronaVac and TURKOVAC vaccines used as a booster dose after CoronaVac primary vaccination. This double-blind, randomized, controlled, phase II, multicenter study included healthy male and female adults (18-60 years) who were vaccinated with two doses of CoronaVac vaccine and did not exceed the duration of at least 90 days and a maximum of 270 days from the second dose of vaccination. Among 236 eligible volunteers, 222 were recruited for randomization between July 12, 2021 and September 10, 2021; 108 and 114 were randomized to the TURKOVAC and CoronaVac arms, respectively. The primary endpoint was adverse events (AEs) (ClinicalTrials.gov; Identifier: NCT04979949). On day 28, at the neutralizing antibody threshold of 1/6, the positivity rate reached 100% from 46.2% to 98.2% from 52.6% in the TURKOVAC and CoronaVac arms, respectively, against the Wuhan variant and the positivity rate reached 80.6% from 8.7% in the TURKOVAC arm vs. 71.9% from 14.0% in the CoronaVac arm against the Delta variant. IgG spike antibody positivity rate increased from 57.3% to 98.1% and from 57.9% to 97.4% in the TURKOVAC and CoronaVac arms, respectively. The TURKOVAC and CoronaVac arms were comparable regarding the frequency of overall AEs. Both vaccines administered as booster yielded higher antibody titers with acceptable safety profiles.

Side Effects after mRNA COVID-19 Vaccine as a Booster in Health Workers

Background

In Indonesia, around 400 health workers died due to Covid-19 between June-July 2021, therefore the health workers need to be given further immunity. Health workers were among the first to get a booster shoot. However, they may experience side effects after vaccination. We aimed to describe side effects of Moderna vaccine as a booster in health workers.

Methods

A cross sectional study was conducted on health workers who received mRNA Covid-19 vaccine booster (Moderna) at Sulianti Saroso Infectious Disease Hospital, Indonesia and had filled the questionnaire assessing side effects form. We associated the form of the questionnaire assessing side effects from the originating source of hospital immunization unit in September 2021.

Results

A total of 101 health workers who received mRNA Covid-19 vaccine booster in Jul-Aug 2021 were included. Most of health worker experienced more than 3 side effects. The side effects were sore arm (100%); chills (72%); fatigue (57%); headache (53%) and fever (51%), other symptoms (28%). The side effects mostly happened a day of receiving a booster shot (61.4%). There was no association between age, gender, comorbid to amount of side effects (P>0.05).

Conclusion

Since the public must fulfil the immunization program during pandemic, it is the responsibility of the healthcare provider to inform about the potential side effects and benefits of a new Covid-19 vaccine.

Absent or suboptimal response to booster dose of COVID-19 vaccine in patients with autoimmune systemic diseases

Autoimmune systemic diseases (ASD) show impaired immunogenicity to COVID-19 vaccines. Our prospective observational multicenter study aimed at evaluating the seroconversion elicited by COVID-19 vaccine over the entire vaccination cycle including the booster dose.

Among 478 unselected ASD patients originally evaluated at the end of the first vaccination cycle (time 1), 344 individuals were re-evaluated after a 6-month period (time 2), and 244 after the booster vaccine dose (time 3). The immunogenicity of mRNA COVID-19 vaccines (BNT162b2 and mRNA-1273) was assessed by measuring serum IgG-neutralizing antibody (NAb) on samples obtained at the three time points in both patients and 502 age-matched controls.

In the 244 ASD group that received booster vaccine and monitored over the entire follow-up, the mean serum NAb levels (time 1, 2, and 3: 696.8 ± 52.68, 370.8 ± 41.92, and 1527 ± 74.16SD BAU/mL, respectively; p < 0.0001) were constantly lower compared to controls (p < 0.0001), but they significantly increased after the booster dose compared to the first two measurements (p < 0.0001). The percentage of patients with absent/suboptimal response to vaccine significantly decreased after the booster dose compared to the first and second evaluations (time 1, 2, and 3: from 28.2% to 46.3%, and to 7.8%, respectively; p < 0.0001). Of note, the percentage of patients with absent/suboptimal response after the booster dose was significantly higher compared to controls (19/244, 7.8% vs 1/502, 0.2%; p < 0.0001). Similarly, treatment with immune-modifiers increased the percentage of patients exhibiting absent/suboptimal response (16/122, 13.1% vs 3/122, 2.46%; p = 0.0031). Overall, the above findings indicate the usefulness of booster vaccine administration in ASD patients. Moreover, the persistence of a significantly higher percentage of individuals without effective seroconversion (7.8%), even after the booster dose, warrants for careful monitoring of NAb levels in all ASD patients to identify those with increased risk of infection. In this particularly frail patients’ setting, tailored vaccination and/or therapeutic strategy are highly advisable.

Neutralizing antibody and T cell responses against SARS-CoV-2 variants of concern following ChAdOx-1 or BNT162b2 boosting in the elderly previously immunized with CoronaVac vaccine

Background

The existence of SARS-CoV-2 variants of concern (VOCs) in association with evidence of breakthrough infections despite vaccination resulted in the need for vaccine boosting. In elderly individuals, information on the immunogenicity of booster vaccinations is limited. In countries where the CoronaVac inactivated vaccine is the primary vaccine, the appropriate boosting regimen is not clear. Immunologic studies of the effects of booster vaccination against VOCs, particularly Delta and Omicron, following CoronaVac in elderly individuals are helpful for policy makers. In this study, we determined the immune responses against VOCs following ChAdOx-1 or BNT162b2 boosting in elderly individuals previously immunized with CoronaVac.

Results

Before boosting, the median % inhibition of neutralizing antibodies (NAbs) against the wild-type (WT), Alpha, Beta, Delta and Omicron variants in the ChAdOx-1 and BNT162b2 groups was 52.8% vs. 53.4, 36.6% vs. 39.9, 5.2% vs. 13.7, 34.3% vs. 44.9, and 20.8% vs. 18.8%, respectively. After boosting with ChAdOx-1 or BNT162b2, the % inhibition of NAbs were increased to 97.3% vs. 97.4, 94.3% vs. 97.3%, 79.9 vs. 93.7, 95.5% vs. 97.5, and 26.9% vs. 31.9% for WT, Alpha, Beta, Delta and Omicron variants, respectively. Boosting with BNT162b2 induced significantly higher NAb levels than boosting with ChAdOx-1 against the Alpha, Beta and Delta variants but not the WT and Omicron variants. NAb levels against Omicron variant were not significantly different before and after boosting with ChAdOx-1 or BNT162b2. To evaluate T-cell responses, S peptides of the WT, Alpha, Beta and Delta variants were used to stimulate T cells. Upon stimulation, the expression of IL-17A in CD8 T cells was higher in the BNT162b2 group than in the ChAdOx-1 boosting group. However, IFN-γ production in CD4 and CD8 T cells did not significantly differ under all vaccination regimens. The expression of FasL in CD4 T cells, but not CD8 T cells, was higher in the BNT162b2-boosted group.

Conclusion

Boosting with either ChAdOx-1 or BNT162b2 in CoronaVac-primed healthy elderly individuals induced high NAb production against all examined VOCs except Omicron. BNT162b2 stimulated higher NAb and some T-cell responses than ChAdOx-1. Vaccine boosting is, therefore, recommended for elderly individuals previously immunized with CoronaVac.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-022-00279-8.

Acceptance of COVID-19 Booster Vaccination Based on the Protection Motivation Theory (PMT): A Cross-Sectional Study in China

The promotion of the booster shots against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection is an open issue to be discussed. Little is known about the public intention and the influencing factors regarding the booster vaccine. A cross‐sectional survey in Chinese adults was conducted using an online questionnaire, which designed on the basis of protection motivation theory (PMT) scale and vaccine hesitancy scale (VHS). Hierarchical multiple regression was used to compare the fitness of the PMT scale and VHS for predicting booster vaccination intention. Multivariable logistic regression was used to analyze the factors associated with the acceptance. Six thousand three hundred twenty‐one (76.8%) of participants were willing to take the booster shot. However, the rest of the participants (23.2%) were still hesitant to take the booster vaccine. The PMT scale was more powerful than the VHS in explaining the vaccination intention. Participants with high perceived severity (adjusted odds ratio [aOR] = 0.69) and response cost (aOR = 0.47) were less willing to take the booster shots, but participants with high perceived susceptibility (aOR = 1.19), response efficacy (aOR = 2.13), and self‐efficacy (aOR = 3.33) were more willing to take the booster shots. In summary, interventions based on PMT can provide guidance to ensure the acceptance of the booster vaccine.

Predictors of uncertainty and unwillingness to receive the COVID-19 booster vaccine: An observational study of 22,139 fully vaccinated adults in the UK

BACKGROUND

The continued success of the COVID-19 vaccination programme in the UK will depend on widespread uptake of booster vaccines. However, there is evidence of hesitancy and unwillingness to receive the booster vaccine, even in fully vaccinated adults. Identifying factors associated with COVID-19 booster vaccine intentions specifically in this population is therefore critical.

METHODS

We used data from 22,139 fully vaccinated adults who took part in the UCL COVID-19 Social Study. Multinomial logistic regression examined predictors of uncertainty and unwillingness (versus willingness) to receive a COVID-19 booster vaccine (measured 22 November 2021 to 6 December 2021), including (i) socio-demographic factors, (ii) COVID-19 related factors (e.g., having been infected with COVID-19), and (iii) initial intent to receive a COVID-19 vaccine in the four months following the announcement in the UK that the vaccines had been approved (2 December 2020 to 31 March 2021).

FINDINGS

4% of the sample reported that they were uncertain about receiving a COVID-19 booster vaccine, and a further 4% unwilling. Initial uncertainty and unwillingness to accept the first COVID-19 vaccine in 2020-21 were each associated with over five times the risk of being uncertain about and unwilling to accept a booster vaccine. Healthy adults (those without a pre-existing physical health condition) were also more likely to be uncertain or unwilling to receive a booster vaccine. In addition, low levels of current stress about catching or becoming seriously ill from COVID-19, consistently low compliance with COVID-19 government guidelines during periods of strict restrictions (e.g., lockdowns), lower levels of educational qualification, lower socio-economic position, and age below 45 years were all associated with uncertainty and unwillingness.

INTERPRETATION

Our findings highlight that there are a range of factors that predict booster intentions, with the strongest predictor being previous uncertainty and unwillingness. Two other concerning patterns also emerged from our results. First, administration of booster vaccinations may increase social inequalities in experiences of COVID-19 as adults from lower socio-economic backgrounds are also most likely to be uncertain or unwilling to accept a booster vaccine as well as most likely to be seriously affected by the virus. Second, some of those most likely to spread COVID-19 (i.e., those with poor compliance with guidelines) are most likely to be uncertain and unwilling. Public health messaging should be tailored specifically to these groups.

FUNDING

The Nuffield Foundation [WEL/FR-000022583], the MARCH Mental Health Network funded by the Cross-Disciplinary Mental Health Network Plus initiative supported by UK Research and Innovation [ES/S002588/1], and the Wellcome Trust [221400/Z/20/Z and 205407/Z/16/Z].

Assessing adolescent immunization options for pertussis in Canada: A cost-utility analysis

BACKGROUND

Adolescent tetanus, diphtheria and pertussis (Tdap) immunization helps prevent pertussis infection. Timing of Tdap receipt represents an important facet of successful adolescent pertussis immunization. Potential strategies for timing of vaccine administration are each associated with different benefits - including disease prevention - and costs. The objective of this study was to assess the cost-utility of adolescent pertussis immunization strategies in Canada.

METHODS

A cost-utility analysis was conducted using a pertussis disease history-simulating Markov model, with adolescents (beginning at age 10 years) as the cohort of interest. The model assessed three Tdap vaccination strategies: (1) immunization of 10 year olds, (2) removal of adolescent vaccination, and (3) immunization of 14 year olds (status quo). The analysis was conducted from a healthcare payer perspective and used a lifetime time horizon. Primary outcomes included life years, quality-adjusted life years (QALYs), health system costs, and an incremental cost-effectiveness ratio (ICER). Costs and outcomes were discounted at 1.5 percent annually. Deterministic and probabilistic sensitivity analyses were performed to assess parameter uncertainty.

RESULTS

The current recommended adolescent immunization strategy (at age 14) resulted in an average of 40.4432 expected QALYs and $26.28 per individual. This strategy was dominated by immunization at 10 years and no immunization. Compared to no immunization, immunizing adolescents at age 10 had an ICER of $74,899 per QALY. Results were most sensitive to the incidence of pertussis and the utility of moderate or severe pertussis. At a cost-effectiveness threshold of $50,000/QALY, removal of adolescent vaccination represented the most cost-effective strategy in 78% of simulations.

CONCLUSION

Analysis assumes a policy context where immunization of pregnant women is recommended. Findings suggest that alternate adolescent Tdap vaccine strategies - either immunization of 10 year olds, or removal of the adolescent vaccine - are more cost-effective than the current practice of immunizing 14 year olds.

Assessment of hepatitis B virus antibody titers in childhood cancer survivors

Pediatric patients suffering from cancer are at risk of hepatitis B virus (HBV) infection and its related complications even though it is considered a vaccine preventable disease. Little is known of the effects of chemotherapy, and even less is known regarding the impact of HBV booster on HBV antibody titers. It is the purpose of this study to investigate and measure the prevalence of the antihepatitis B surface antibodies (HBsAb) in childhood cancer survivors after completion of their chemotherapy treatment and to further evaluate survivors' response to a single booster dose of HBV vaccine. This observational, cross-sectional retrospective study included 43 patients, of which 37 (86%) were found to be seronegative (HBsAb titer <10 mIU/ml). The notable result was that, of the seronegative patients who received a booster dose of HBV vaccine, 90% of the tested cases exhibited a successful raising of HBsAb titers >10 mIU/ml.

CONCLUSION

Childhood cancer survivors have high seronegative rates for HBV and the majority of the patients achieved HBsAb titer > 10mIU/ml with a single booster dose of HBV vaccine, which is worth further investigation and research. This study suggests revaccination against HBV post-chemotherapy treatment, as the recommended advice, especially in countries with a high prevalence of HBV infection. What is Known: • There is a variable prevalence of low HBsAb titers measured after the end of chemotherapy in childhood cancer survivors. • There are no universal guidelines for revaccination of these patients. What is New: • This research identified that 86% of childhood cancer survivors treated with standard chemotherapy were seronegative for HBV infection. • A single booster dose HBV vaccine was successful for the majority of patients (90%) to achieve HBsAb titers >10 mIU/ml.

Mycobacterium indicus pranii as a booster vaccine enhances BCG induced immunity and confers higher protection in animal models of tuberculosis

BCG, the only approved vaccine protects against severe form of childhood tuberculosis but its protective efficacy wanes in adolescence. BCG has reduced the incidence of infant TB considerably in endemic areas; therefore prime-boost strategy is the most realistic measure for control of tuberculosis in near future. Mycobacterium indicus pranii (MIP) shares significant antigenic repertoire with Mtb and BCG and has been shown to impart significant protection in animal models of tuberculosis. In this study, MIP was given as a booster to BCG vaccine which enhanced the BCG mediated immune response, resulting in higher protection. MIP booster via aerosol route was found to be more effective in protection than subcutaneous route of booster immunization. Pro-inflammatory cytokines like IFN-γ, IL-12 and IL-17 were induced at higher level in infected lungs of 'BCG-MIP' group both at mRNA expression level and in secretory form when compared with 'only BCG' group. BCG-MIP groups had increased frequency of multifunctional T cells with high MFI for IFN-γ and TNF-α in Mtb infected mice. Our data demonstrate for the first time, potential application of MIP as a booster to BCG vaccine for efficient protection against tuberculosis. This could be very cost effective strategy for efficient control of tuberculosis.