Immunization Newsletter, v.46, n.1, Mar. 2024

The Pan American Health Organization (PAHO) publishes the Immunization Newsletter four times a year in English, French, Portuguese, and Spanish. Its purpose is to facilitate the exchange of ideas and information on immunization programs in the Region of the Americas and beyond. It has been published since 1979 in English and Spanish, with French and Portuguese versions beginning in 2001 and 2019, respectively. The March 2024 issue of the quarterly Immunization Newsletter covers the following topics: Third annual meeting of the Regional Monitoring and Re-verification Commission for Measles, Rubella, and Congenital Rubella Syndrome Elimination; PAHO’s Technical Advisory Group (TAG) on Vaccine-preventable Diseases provides regional recommendations on dengue and respiratory syncytial virus vaccines and issues a statement on the ongoing COVID-19 vaccination efforts; Charting the path forward: reflections on PAHO's Communicable Diseases Elimination Initiative and future directions; Towards the Elimination of Diseases Associated with Human Papillomavirus Infection in the French Caribbean: Implementation of a Mass Vaccination Campaign in Schools Since October 2023; Expanded Immunization Program methodology and performance monitoring tool for the Region of the Americas; Sentinel surveillance of rotavirus in children under 5 years of age in the Region of the Americas; Sentinel surveillance of bacterial pneumonia and meningitis in children under 5 years of age in the Americas; Workshop on the preparation of scientific texts and articles on health in Bogotá, Colombia; Final Classification of Cases in the Region of the Americas, 2023; Immunization information systems and data quality; Virtual self-learning course: Tools for monitoring integrated public health interventions. Vaccination and deworming for soil-transmitted helminth infections; and Strengthening immunization data management.

Boletín de Inmunización, v.46, n.1, Mar. 2024

La Organización Panamericana de la Salud (OPS) publica cuatro veces al año el Boletín de Inmunización en español, francés, inglés y portugués. Su propósito es facilitar el intercambio de ideas e información sobre los programas de inmunización en la Región de las Américas y más allá. Se publica desde 1979 en inglés y español, con versiones en francés y portugués a partir de 2001 y 2019, respectivamente. El número de marzo del 2024 del Boletín de Inmunización abarca los siguientes temas: Tercera reunión anual de la Comisión Regional de Monitoreo y Reverificación de la Eliminación del Sarampión, la Rubéola y el Síndrome de Rubeola Congénita; El Grupo Técnico Asesor de la OPS sobre Enfermedades Prevenibles por Vacunación ofrece recomendaciones sobre las vacunas contra el dengue y el virus respiratorio sincitial a nivel regional y emite una declaración referente a los esfuerzos continuos de vacunación contra la COVID-19; Trazando el camino a seguir: reflexiones sobre la Iniciativa para la Eliminación de Enfermedades Transmisibles de la OPS y orientaciones futuras; Hacia la eliminación de las enfermedades debidas al virus del papiloma humano en el Caribe francés: puesta en marcha de una campaña de vacunación masiva en las escuelas a partir de octubre del 2023; Metodología y herramienta de monitoreo del desempeño del Program Ampliado de Inmunización para la Región de las Américas; Vigilancia centinela de rotavirus en los menores de 5 años en la Región de las Américas; Vigilancia centinela de neumonías y meningitis bacterianas en menores de 5 años de edad en las Américas; Taller de Elaboración de textos y artículos científicos en el ámbito de la salud en Bogotá (Colombia); Clasificación final de casos en la Región de las Américas, 2022; El sistema de información de inmunización y la calidad de los datos; Curso virtual de autoaprendizaje “Herramientas para el monitoreo de intervenciones integradas en salud pública. Vacunación y desparasitación para las geohelmintiasis”; y Fortalecer la gestión de los datos de inmunizaciones.

Immunogenicity of COVID-19 booster vaccination in IEI patients and their one year clinical follow-up after start of the COVID-19 vaccination program.

Purpose: Previous studies have demonstrated that the majority of patients with an inborn error of immunity (IEI) develop a spike (S)-specific IgG antibody and T-cell response after two doses of the mRNA-1273 COVID-19 vaccine, but little is known about the response to a booster vaccination. We studied the immune responses 8 weeks after booster vaccination with mRNA-based COVID-19 vaccines in 171 IEI patients. Moreover, we evaluated the clinical outcomes in these patients one year after the start of the Dutch COVID-19 vaccination campaign. Methods: This study was embedded in a large prospective multicenter study investigating the immunogenicity of COVID-19 mRNA-based vaccines in IEI (VACOPID study). Blood samples were taken from 244 participants 8 weeks after booster vaccination. These participants included 171 IEI patients (X-linked agammaglobulinemia (XLA;N=11), combined immunodeficiency (CID;N=4), common variable immunodeficiency (CVID;N=45), isolated or undefined antibody deficiencies (N=108) and phagocyte defects (N=3)) and 73 controls. SARS-CoV-2-specific IgG titers, neutralizing antibodies, and T-cell responses were evaluated. One year after the start of the COVID-19 vaccination program, 334 study participants (239 IEI patients and 95 controls) completed a questionnaire to supplement their clinical data focusing on SARS-CoV-2 infections. Results: After booster vaccination, S-specific IgG titers increased in all COVID-19 naive IEI cohorts and controls, when compared to titers at 6 months after the priming regimen. The fold-increases did not differ between controls and IEI cohorts. SARS-CoV-2-specific T-cell responses also increased equally in all cohorts after booster vaccination compared to 6 months after the priming regimen. Most SARS-CoV-2 infections during the study period occurred in the period when the Omicron variant had become dominant. The clinical course of these infections was mild, although IEI patients experienced more frequent fever and dyspnea compared to controls and their symptoms persisted longer. Conclusion: Our study demonstrates that mRNA-based booster vaccination induces robust recall of memory B-cell and T-cell responses in most IEI patients. One-year clinical follow-up demonstrated that SARS-CoV-2 infections in IEI patients were mild. Given our results, we support booster campaigns with newer variant-specific COVID-19 booster vaccines to IEI patients with milder phenotypes.

Report from the World Health Organization's immunization and vaccines-related implementation research advisory committee (IVIR-AC) meeting, virtual gathering, 26 February-1 March 2024.

The Immunization and Vaccine-related Implementation Research Advisory Committee (IVIR-AC) is the World Health Organization's key standing advisory body to conduct an independent review of research, particularly of transmission and economic modeling analyses that estimate the impact and value of vaccines. From 26th February-1st March 2024, at its first of two semi-annual meetings, IVIR-AC provided feedback and recommendations across four sessions; this report summarizes the proceedings and recommendations from that meeting. Session topics included modeling of the impact and cost-effectiveness of the R21/Matrix-M malaria vaccine, meta-analysis of economic evaluations of vaccines, a global analysis estimating the impact of vaccination over the last 50 years, and modeling the impact of different RTS,S malaria vaccine dose schedules in seasonal settings.

Determinants of uptake of influenza, zoster and pneumococcal vaccines in patients with cardiovascular diseases.

BACKGROUND: Globally, cardiovascular disease (CVD) is the leading cause of death and illness. Vaccine-preventable infections may increase acute coronary vascular disease events and the risk of complications. Low vaccine coverage has been reported among adults at high risk of complications from vaccine-preventable infections. There is a gap in research evidence around determinants of uptake of vaccines among adults with CVD. This study examined the uptake of influenza, pneumococcal and zoster vaccines and the determinants of uptake of the vaccines among cardiac patients. METHOD: A prospective cross-sectional study was carried out among hospitalised cardiac patients through an interviewer-administered questionnaire. Descriptive statistics were used to investigate self-reported uptake of influenza, pneumococcal and zoster vaccines. Univariate and multivariate analyses of participants' social demographic and clinical characteristics were conducted to identify factors for receiving influenza vaccine. RESULTS: Low vaccination rates among 104 participants were found for influenza (45.2%), pneumococcal (13.5%) and zoster (5.8%) vaccines. The most common reason for not receiving influenza vaccine was concern about side effects. Lack of awareness about the pneumococcal and zoster vaccines was the main reason for the poor uptake of these vaccines. Australia-born participants were more likely to receive influenza vaccine than overseas-born participants. Working-age participants and, interestingly, people living with a current smoker were less likely to receive influenza vaccine. CONCLUSION: Influenza, pneumococcal and zoster vaccine uptake among cardiac patients was low. Encouraging physician recommendations for vaccination for cardiac patients under 65 years of age and addressing vaccination challenges among people from culturally and linguistically diverse backgrounds and pharmacy, workplace, and hospital vaccination may help increase vaccination uptake among cardiac patients.

Immunogenicity and safety of a recombinant Omicron BA.4/5-Delta COVID-19 vaccine ZF2202-A in Chinese adults.

BACKGROUND: The Recombinant Omicron BA.4/5-Delta COVID-19 Vaccine (ZF2202-A) is primarily designed for the Delta and Omicron BA.4/5 variants. Our objective was to assess the safety and immunogenicity of ZF2202-A in Chinese adults. METHODS: A total of 450 participants aged ≥ 18 years, who had completed primary or booster vaccination with a COVID-19 vaccine more than 6 months prior, were enrolled in this randomized, double-blind, active-controlled trial. Participants in the study and control groups were administered one dose of ZF2202-A and ZF2001, respectively. Immunogenicity subgroups were established in each group. RESULTS: At 14 days after vaccination, the seroconversion rates of Omicron BA.4/5, BF.7, and XBB.1 in the ZF2022-A group were 67.7 %, 58.6 %, and 62.6 %, with geometric mean titers (GMTs) of neutralizing antibodies at 350.2, 491.8, and 49.5, respectively. The main adverse reactions (ARs) were vaccination site pain, pruritus, fatigue, and asthenia in both the ZF2022-A group and ZF2001 group. CONCLUSIONS: The novel bivalent vaccine ZF2202-A demonstrated satisfactory immunogenicity and safety against Omicron variants as booster dose in adults with prior vaccination of COVID-19 vaccines.

Assessment of potential adverse events following the 2022-2023 seasonal influenza vaccines among U.S. adults aged 65 years and older.

BACKGROUND: While safety of influenza vaccines is well-established, some studies have suggested potential associations between influenza vaccines and certain adverse events (AEs). This study examined the safety of the 2022-2023 influenza vaccines among U.S. adults ≥ 65 years. METHODS: A self-controlled case series compared incidence rates of anaphylaxis, encephalitis/encephalomyelitis, Guillain-Barré Syndrome (GBS), and transverse myelitis following 2022-2023 seasonal influenza vaccinations (i.e., any, high-dose or adjuvanted) in risk and control intervals among Medicare beneficiaries ≥ 65 years. We used conditional Poisson regression to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) adjusted for event-dependent observation time and seasonality. Analyses also accounted for uncertainty from outcome misclassification where feasible. For AEs with any statistically significant associations, we stratified results by concomitant vaccination status. RESULTS: Among 12.7 million vaccine recipients, we observed 76 anaphylaxis, 276 encephalitis/encephalomyelitis, 134 GBS and 75 transverse myelitis cases. Only rates of anaphylaxis were elevated in risk compared to control intervals. With all adjustments, an elevated, but non-statistically significant, anaphylaxis rate was observed following any (IRR: 2.40, 95% CI: 0.96-6.03), high-dose (IRR: 2.31, 95% CI: 0.67-7.91), and adjuvanted (IRR: 3.28, 95% CI: 0.71-15.08) influenza vaccination; anaphylaxis IRRs were 2.54 (95% CI: 0.49-13.05) and 1.64 (95% CI: 0.38-7.05) for persons with and without concomitant vaccination, respectively. CONCLUSIONS: Rates of encephalitis/encephalomyelitis, GBS, or transverse myelitis were not elevated following 2022-2023 seasonal influenza vaccinations among U.S. adults ≥ 65 years. There was an increased rate of anaphylaxis following influenza vaccination that may have been influenced by concomitant vaccination.

Lipid nanoparticle composition for adjuvant formulation modulates disease after influenza virus infection in quadrivalent influenza vaccine vaccinated mice.

There are considerable avenues through which currently licensed influenza vaccines could be optimized. We tested influenza vaccination in a mouse model with two adjuvants: Sendai virus-derived defective interfering (SDI) RNA, a RIG-I agonist; and an amphiphilic imidazoquinoline (IMDQ-PEG-Chol), a TLR7/8 agonist. The negatively charged SDI RNA was formulated into lipid nanoparticles (LNPs) facilitating direct delivery of SDI RNA to the cytosol, where RIG-I sensing induces inflammatory and type I interferon responses. We previously tested SDI RNA and IMDQ-PEG-Chol as standalone and combination adjuvants for influenza and SARS-CoV-2 vaccines. Here, we tested two different ionizable lipids, K-Ac7-Dsa and S-Ac7-Dog, for LNP formulations. The LNPs were incorporated with SDI RNA to determine its potential as a combination adjuvant with IMDQ-PEG-Chol by evaluating the host immune response to vaccination and infection in immunized BALB/c mice. Adjuvanticity of IMDQ-PEG-Chol with and without empty or SDI-loaded LNPs was validated with quadrivalent inactivated influenza vaccine (QIV), showing robust induction of antibody titers and T-cell responses. Depending on the adjuvant combination and LNP formulation, humoral and cellular vaccine responses could be tailored towards type 1 or type 2 host responses with specific cytokine profiles that correlated with the protective responses to viral infection. The extent of protection conferred by different vaccine/LNP/adjuvant combinations was tested by challenging mice with a vaccine-matched strain of influenza A virus A/Singapore/gp1908/2015 IVR-180 (H1N1). Groups that received either LNP formulated with SDI or IMDQ-PEG-Chol, or both, showed very low levels of viral replication in their lungs at 5 days post-infection (DPI). These studies provide evidence that the combination of vaccines with LNPs and/or adjuvants promote antigen-specific cellular responses that can contribute to protection upon infection. Interestingly, we observed differences in humoral and cellular responses to vaccination between different groups receiving K-Ac7-Dsa or S-Ac7-Dog lipids in LNP formulations. The differences were also reflected in inflammatory responses in lungs of vaccinated animals to infection, depending on LNP formulations. Therefore, this study suggests that the composition of the LNPs, particularly the ionizable lipid, plays an important role in inducing inflammatory responses in vivo, which is important for vaccine safety and to prevent adverse effects upon viral exposure.

TLR agonists polarize interferon responses in conjunction with dendritic cell vaccination in malignant glioma: a randomized phase II Trial.

In this randomized phase II clinical trial, we evaluated the effectiveness of adding the TLR agonists, poly-ICLC or resiquimod, to autologous tumor lysate-pulsed dendritic cell (ATL-DC) vaccination in patients with newly-diagnosed or recurrent WHO Grade III-IV malignant gliomas. The primary endpoints were to assess the most effective combination of vaccine and adjuvant in order to enhance the immune potency, along with safety. The combination of ATL-DC vaccination and TLR agonist was safe and found to enhance systemic immune responses, as indicated by increased interferon gene expression and changes in immune cell activation. Specifically, PD-1 expression increases on CD4+ T-cells, while CD38 and CD39 expression are reduced on CD8+ T cells, alongside an increase in monocytes. Poly-ICLC treatment amplifies the induction of interferon-induced genes in monocytes and T lymphocytes. Patients that exhibit higher interferon response gene expression demonstrate prolonged survival and delayed disease progression. These findings suggest that combining ATL-DC with poly-ICLC can induce a polarized interferon response in circulating monocytes and CD8+ T cells, which may represent an important blood biomarker for immunotherapy in this patient population.Trial Registration: ClinicalTrials.gov Identifier: NCT01204684.

Cardioprotective effects of vaccination in hospitalized patients with COVID-19.

COVID-19 vaccination has been shown to prevent and reduce the severity of COVID-19 disease. The aim of this study was to explore the cardioprotective effect of COVID-19 vaccination in hospitalized COVID-19 patients. In this retrospective, single-center cohort study, we included hospitalized COVID-19 patients with confirmed vaccination status from July 2021 to February 2022. We assessed outcomes such as acute cardiac events and cardiac biomarker levels through clinical and laboratory data. Our analysis covered 167 patients (69% male, mean age 58 years, 42% being fully vaccinated). After adjustment for confounders, vaccinated hospitalized COVID-19 patients displayed a reduced relative risk for acute cardiac events (RR: 0.33, 95% CI [0.07; 0.75]) and showed diminished troponin T levels (Cohen's d: - 0.52, 95% CI [- 1.01; - 0.14]), compared to their non-vaccinated peers. Type 2 diabetes (OR: 2.99, 95% CI [1.22; 7.35]) and existing cardiac diseases (OR: 4.31, 95% CI [1.83; 10.74]) were identified as significant risk factors for the emergence of acute cardiac events. Our findings suggest that COVID-19 vaccination may confer both direct and indirect cardioprotective effects in hospitalized COVID-19 patients.

Protecting the vulnerable: addressing the COVID-19 care needs of people with compromised immunity.

While the general population regained a certain level of normalcy with the end of the global health emergency, the risk of contracting COVID-19 with a severe outcome is still a major concern for people with compromised immunity. This paper reviews the impact of COVID-19 on people with immunocompromised status, identifies the gaps in the current management landscape, and proposes actions to address this unmet need. Observational studies have demonstrated that people with immune dysfunction have a higher risk of COVID-19-related hospitalization and death, despite vaccination, than the general population. More research is needed to define the optimal prevention and treatment strategies that are specific to people with immunocompromised status, including novel vaccination strategies, monoclonal antibodies that provide passive immunity and complement suboptimal vaccination responses, and improved and safer antiviral treatment for COVID-19. Preventive measures beyond vaccination alone are urgently needed to protect this vulnerable population.

Original COVID-19 priming regimen impacts the immunogenicity of bivalent BA.1 and BA.5 boosters.

Waning antibody responses after COVID-19 vaccination combined with the emergence of the SARS-CoV-2 Omicron lineage led to reduced vaccine effectiveness. As a countermeasure, bivalent mRNA-based booster vaccines encoding the ancestral spike protein in combination with that of Omicron BA.1 or BA.5 were introduced. Since then, different BA.2-descendent lineages have become dominant, such as XBB.1.5, JN.1, or EG.5.1. Here, we report post-hoc analyses of data from the SWITCH-ON study, assessing how different COVID-19 priming regimens affect the immunogenicity of bivalent booster vaccinations and breakthrough infections (NCT05471440). BA.1 and BA.5 bivalent vaccines boosted neutralizing antibodies and T-cells up to 3 months after boost; however, cross-neutralization of XBB.1.5 was poor. Interestingly, different combinations of prime-boost regimens induced divergent responses: participants primed with Ad26.COV2.S developed lower binding antibody levels after bivalent boost while neutralization and T-cell responses were similar to mRNA-based primed participants. In contrast, the breadth of neutralization was higher in mRNA-primed and bivalent BA.5 boosted participants. Combined, our data further support the current use of monovalent vaccines based on circulating strains when vaccinating risk groups, as recently recommended by the WHO. We emphasize the importance of the continuous assessment of immune responses targeting circulating variants to guide future COVID-19 vaccination policies.

Parental hesitancy toward children vaccination: a multi-country psychometric and predictive study.

AIM: Understanding vaccine hesitancy, as a critical concern for public health, cannot occur without the use of validated measures applicable and relevant to the samples they are assessing. The current study aimed to validate the Vaccine Hesitancy Scale (VHS) and to investigate the predictors of children's vaccine hesitancy among parents from Australia, China, Iran, and Turkey. To ensure the high quality of the present observational study the STROBE checklist was utilized. DESIGN: A cross-sectional study. METHOD: In total, 6,073 parent participants completed the web-based survey between 8 August 2021 and 1 October 2021. The content and construct validity of the Vaccine Hesitancy Scale was assessed. Cronbach's alpha and McDonald's omega were used to assess the scale's internal consistency, composite reliability (C.R.) and maximal reliability (MaxR) were used to assess the construct reliability. Multiple linear regression was used to predict parental vaccine hesitancy from gender, social media activity, and perceived financial well-being. RESULTS: The results found that the VHS had a two-factor structure (i.e., lack of confidence and risk) and a total of 9 items. The measure showed metric invariance across four very different countries/cultures, showed evidence of good reliability, and showed evidence of validity. As expected, analyses indicated that parental vaccine hesitancy was higher in people who identify as female, more affluent, and more active on social media. CONCLUSIONS: The present research marks one of the first studies to evaluate vaccine hesitancy in multiple countries that demonstrated VHS validity and reliability. Findings from this study have implications for future research examining vaccine hesitancy and vaccine-preventable diseases and community health nurses.

Clinical characteristics of COVID-19 patients treated in emergency COVID-19 hospitals in Vietnam: Experience from Phutho province, Vietnam.

Background: This study aimed to evaluate the clinical characteristics, patient's management approaches, and outcomes of the COVID-19 patients in Phu Tho Province, Vietnam. Methods: A retrospective, multicenter study of 2166 COVID-19 patients in 13 hospitals in Phutho Province, Vietnam. The subjects were divided into 3 groups based on vaccination status: unvaccinated group, 1st dose of vaccine group, 2nd dose of vaccine group. The clinical characteristics, management approaches, and outcomes were collected and compared between the 3 groups. Results: The hospitalization rate of the 3 groups decreased from the unvaccinated group, the 1st dose of vaccinated group, to the 2nd dose of vaccinated group, 42.61%; 30,24% and 27,15% respectively. The 19-40 years old group had the highest hospitalization rate (38,1%) together with the group that had not accepted the full COVID 19 vaccination dose (57,64%). The 2nd dose of vaccinated group had the lowest percentages of high temperature, cough, dyspnea, chest pain and sore throat. The unvaccinated group had the highest heart rate, respiratory rate and SpO2 compared to the two other groups. The percentage needing Immunomodulation and Anticoagulant Therapy was highest (6.8% and 1.4 % respectively) in the unvaccinated group. The percentage receiving Antiviral Therapy was highest (42,5%) in those who had received the 2nd dose of vaccine. Conclusions: COVID-19 vaccination improved the symptoms of the patients and should be accepted in all ages.

Language barriers during vaccination practice, the point of view of healthcare providers.

Background: Language barriers are one of the main obstacles faced by migrants in accessing healthcare services. A compromised communication between migrants and Healthcare Providers in vaccination setting can result in increased vaccine hesitancy and decreased vaccine uptake. The objective of the current study is to investigate Healthcare Providers' perceptions about linguistic barriers faced during both routinary vaccination practice and the extraordinary vaccination program for Ukrainian refugees in the Local Health Authorities of Bologna and Romagna (Italy). Methods: A cross-sectional study was conducted through the administration of a questionnaire examining Healthcare Providers' perceptions. A descriptive analysis and a multiple logistic regression model were adopted to analyze the collected data. Results: Language barriers resulted as an obstacle to informed consent and to doctor-patient relationship. The strategies adopted were perceived as helpful in increasing vaccination adherence, despite communication difficulties were still experienced during refugees' vaccinations. Results suggest that the implementation of translated material and the use of professional interpreters may represent important strategies to overcome linguistic barriers, along with Healthcare Providers' training. Healthcare Providers' opinions could assist the implementation of new tools capable of countering language barriers. Conclusions: The current study represents an example of providers' involvement in understanding the complexities behind the issue of language barriers in vaccination practice.

Vaccine Confidence as Critical to Pandemic Preparedness and Response.

Vaccine confidence is a belief that vaccines work, are safe, and are part of a trustworthy medical system. The COVID-19 pandemic exposed the fragility of the public's confidence in vaccines and the vaccine enterprise, limiting the public health impact of vaccination. In this review, we examine the critical nature of vaccine confidence to pandemic preparedness and response.