Respiratory Syncytial Virus Prefusion F Subunit Vaccine: First Approval of a Maternal Vaccine to Protect Infants

Attitude to RSV Vaccination Among a Cohort of Pregnant Women in Jordan: A Cross-Sectional Survey Study

Background and Aims

The recently approved maternal vaccination against respiratory syncytial virus (RSV) can reduce its burden among infants. However, vaccine hesitancy/resistance can undermine the beneficial impact of RSV vaccination. The aim of this study was to assess the willingness of pregnant women in Jordan to receive RSV vaccination and its associated determinants.

Methods

Face-to-face interviews were conducted in obstetrics/gynecology clinics in the Central, Northern, and Southern regions of Jordan during January-February 2024, using a convenience sampling approach. Attitude to RSV vaccination was assessed using the previously validated ABCDEF scale.

Results

A total of 404 pregnant women participated in the study with a mean age of 30.1 ± 6.2 years. A majority of the participants showed willingness to receive RSV vaccination (n = 313, 77.5%), with hesitancy among 25 participants (6.2%), and resistance among 66 participants (16.3%). Variables that were significantly associated with a higher RSV vaccine acceptance in multivariate analysis were: age < 30 years (adjusted odds ratio (aOR): 2.45, p = 0.010), undergraduates (aOR: 3.27, p = 0.026), being a healthcare worker (aOR: 4.50, p = 0.036), and the history of previous COVID-19/influenza vaccine uptake (aOR: 2.47, p = 0.045). Two out of the six ABCDEF constructs were significantly associated with RSV vaccine acceptance, namely the "Advice" construct (aOR: 10.38, p < 0.001) and the "Fear" construct (aOR: 21.49, p < 0.001).

Conclusion

This study highlighted the complex nature of attitude towards maternal RSV vaccination among pregnant women. The study showed the role of demographic variables, prior vaccination experience, trust in credible health institutions and vaccine safety, and the fear of RSV disease consequences in infants in shaping maternal attitude to RSV vaccination. Addressing these factors can help to effectively promote RSV vaccine uptake among pregnant women, subsequently helping to protect infants from the significant RSV disease burden.

Platform Technology in Global Vaccine Regulation: Development, Applications, and Regulatory Strategies with Insights from China

The concept of "platform technology" gained prominence after the Ebola outbreak and since then has become essential to international vaccine (prophylactic vaccines against infectious disease) regulatory frameworks. Its significance was further amplified during the COVID-19 pandemic, where platform technology enabled the rapid development and approval of vaccines, optimizing regulatory processes, and enhancing global public health responses. As a transformative tool, platform technology streamlines product development, allowing for the reduction in the number of clinical trials or exemption from certain clinical trials and facilitating cross-referencing in regulatory submissions. Despite significant efforts to establish standardized regulatory procedures, challenges remain, particularly in achieving a unified definition and application of platform technology across regions. This paper explores the evolution, applications, and regulatory strategies of platform technology, with a focus on China's experience in this field. China's approach, encompassing risk assessment, and the expedited approval of emergency vaccines, offers valuable insights into global regulatory coordination. By analyzing China's regulatory contributions and international practices, this paper highlights the potential of platform technology to address future pandemics, including "Pathogen X", and underscores the importance of harmonizing global regulatory efforts to strengthen public health preparedness and response.

Vaccine and therapeutic agents against the respiratory syncytial virus: resolved and unresolved issue

Respiratory syncytial virus (RSV) is a predominant pathogen responsible for respiratory tract infections among infants, the elderly, and immunocompromised individuals. In recent years, significant progress has been made in innovative vaccines and therapeutic agents targeting RSV. Nevertheless, numerous challenges and bottlenecks persist in the prevention and treatment of RSV infections. This review will provide an overview of the resolved and unresolved issues surrounding the development of vaccines and therapeutic agents against RSV. As of September 2024, three RSV vaccines against acute lower respiratory infections (ALRI) have been approved globally. Additionally, there have been notable progress in the realm of passive immunoprophylactic antibodies, with the monoclonal antibody nirsevimab receiving regulatory approval for the prevention of RSV infections in infants. Furthermore, a variety of RSV therapeutic agents are currently under clinical investigation, with the potential to yield breakthrough advancements in the foreseeable future. This review delineates the advancements and challenges faced in vaccines and therapeutic agents targeting RSV. It aims to provide insights that will guide the development of effective preventive and control measures for RSV.

Ad26.RSV.preF completely protects calves from severe respiratory disease induced by bovine RSV challenge

Vaccination with Ad26.RSV.preF, an Adenoviral serotype 26 vector encoding RSV F protein stabilized in its prefusion conformation, has previously shown to be immunogenic and protective in RSV seropositive adults and immunogenic in seropositive infants. Human and bovine RSV (bRSV) are genetically highly related and share many aspects of pathogenesis, epidemiology and clinical manifestations at young age. As such, infection of calves with bRSV represents a clinically relevant model with high translational value, enabling preclinical evaluation of Ad26.RSV.preF vaccine efficacy in seronegative young animals. Immunization of young calves with Ad26.RSV.preF induced antibodies neutralizing both human and bovine RSV as well as RSV-specific cellular responses. After bRSV challenge, placebo immunized calves showed viral replication in the respiratory tract, and developed fever and lethargy accompanied with severe respiratory distress, resulting in pre-termination of 7/8 calves. In contrast, all Ad26.RSV.preF immunized calves completed the study with only mild clinical symptoms, strongly and significantly diminished viral loads in nasopharynx and lungs, and only minimal lung pathology. Thus, Ad26.RSV.preF is immunogenic in young calves and efficacious in a stringent heterologous bRSV challenge model, demonstrating induction of broadly protective immunity against severe disease.

Use of the Abrysvo Vaccine in Pregnancy to Prevent Respiratory Syncytial Virus in Infants: A Review

The FDA's approval of Pfizer's new respiratory syncytial virus (RSV) prefusion (preF) vaccine, Abrysvo, marks a critical milestone in infant health and well-being by preventing lower respiratory tract infections in the most vulnerable. The vaccine has been approved for administration to pregnant women at 32 to 36 weeks of gestation and elderly people over 60. This review explores the Abrysvo vaccine, detailing its mechanism, efficacy, safety, and adverse events. It aims to inform healthcare providers about this vital method for safeguarding infant respiratory health through maternal immunization.

Experimental trials of predicted CD4+ and CD8+ T-cell epitopes of respiratory syncytial virus

Background

Respiratory syncytial virus (RSV) is the most common cause of viral lower respiratory tract infections (LRTIs) in young children around the world and an important cause of LRTI in the elderly. The available treatments and FDA-approved vaccines for RSV only lessen the severity of the infection and are recommended for infants and elderly people.

Methods

We focused on developing a broad-spectrum vaccine that activates the immune system to directly combat RSV. The objective of this study is to identify CD4+ and CD8+ T-cell epitopes using an immunoinformatics approach to develop RSV vaccines. The efficacy of these peptides was validated through in-vitro and in-vivo studies involving healthy and diseased animal models.

Results

For each major histocompatibility complex (MHC) class-I and II, we found three epitopes of RSV proteins including F, G, and SH with an antigenic score of >0.5 and a projected SVM score of <5. Experimental validation of these peptides on female BALB/c mice was conducted before and after infection with the RSV A2 line 19f. We found that the 3RVMHCI (CD8+) epitope of the F protein showed significant results of white blood cells (19.72 × 103 cells/μl), neutrophils (6.01 × 103 cells/μl), lymphocytes (12.98 × 103 cells/μl), IgG antibodies (36.9 µg/ml), IFN-γ (86.96 ng/L), and granzyme B (691.35 pg/ml) compared to control at the second booster dose of 10 µg. Similarly, 4RVMHCII (CD4+) of the F protein substantially induced white blood cells (27.08 × 103 cells/μl), neutrophils (6.58 × 103 cells/μl), lymphocytes (16.64 × 103 cells/μl), IgG antibodies (46.13 µg/ml), IFN-γ (96.45 ng/L), and granzyme B (675.09 pg/ml). In-vitro studies showed that 4RVMHCII produced a significant level of antibodies in sera on day 45 comparable to mice infected with the virus. 4RVMHCII also induced high IFN-γ and IL-2 secretions on the fourth day of the challenge compared to the preinfectional stage.

Conclusion

In conclusion, epitopes of the F protein showed considerable immune response and are suitable for further validation.

Obstetric and neonatal outcomes in South Africa

BACKGROUND

Background epidemiologic population data from low- and middle-income countries (LMIC), on maternal, foetal and neonatal adverse outcomes are limited. We aimed to estimate the incidence of maternal, foetal and neonatal adverse outcomes at South African maternal vaccine trial sites as reported directly in the clinical notes as well as using the 'Global Alignment of Immunization Safety Assessment in Pregnancy' case definitions (GAIA-CDs). GAIA-CDs were utilized as a tool to standardise data collection and outcome assessment, and the applicability and utility of the GAIA-CDs was evaluated in a LMIC observational study.

METHODS

We conducted a retrospective record review of maternity and neonatal case records for births that occurred in Soweto, Inner City- Johannesburg and Metro-East Cape Town, South Africa, between 1st July 2017 and 30th June 2018. Study staff abstracted data from randomly selected medical charts onto standardized study-specific forms. Incidence (per 100,000 population) was calculated for adverse maternal, foetal and neonatal outcomes, which were identified as priority outcomes in vaccine safety studies by the Brighton Collaboration and World Health Organization. Outcomes reported directly in the clinical notes and outcomes which fulfilled GAIA-CDs were compared. Incidence of outcomes was calculated by combining cases which were either reported in clinical notes by attending physicians and/ or fulfilled GAIA-CDs.

FINDINGS

Of 9371 pregnant women enrolled, 27·6% were HIV-infected, 19·9% attended antenatal clinic in the 1st trimester of pregnancy and 55·3% had ≥1 ultrasound examination. Fourteen percent of women had hypertensive disease of pregnancy, 1·3% had gestational diabetes mellitus and 16% experienced preterm labour. There were 150 stillbirths (1·6%), 26·8% of infants were preterm and five percent had microcephaly. Data available in clinical notes for some adverse outcomes, including maternal- & neonatal death, severe pre-eclampsia/ eclampsia, were able to fulfil GAIA-CDs criteria for all of the clinically-reported cases, however, missing data required to fulfil other GAIA-CD criteria (including stillbirth, gestational diabetes mellitus and gestational hypertension) led to poor correlation between clinically-reported adverse outcomes and outcomes fulfilling GAIA-CDs. Challenges were also encountered in accurately ascertaining gestational age.

INTERPRETATION

This study contributes to the expanding body of data on background rates of adverse maternal and foetal/ neonatal outcomes in LMICs. Utilization of GAIA-CDs assists with alignment of data, however, some GAIA-CDs require amendment to improve the applicability in LMICs.

FUNDING

This study was funded by Pfizer (Inc).