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Flu News Friday 11/5/21

Read the latest on influenza vaccines in this week’s roundup.

A scientist performs a plaque assay test

The Latest in Influenza Vaccines

1. A Live Probiotic Vaccine Prototype Based on Conserved Influenza a Virus Antigens Protect Mice against Lethal Influenza Virus Infection 
Mezhenskaya et al., Biomedicines 2021, October 19, 2021

Seasonal influenza vaccines require substantial preparation each year to remain effective against circulating flu strains. Due to the highly variable nature of antigenic properties of influenza virus, great efforts have been made to develop a universal vaccine which offers long-lasting protection against various influenza subtypes. In this study, researchers generated two probiotic vaccine candidates expressing either HA2 hemagglutinin subunit of H1N1 influenza virus or its conserved part, LAH antigen, in combination with four conserved M2e epitopes to assess cross-protective potential for universal influenza vaccine development.

2. Adenoviral vector-based platforms for developing effective vaccines to combat respiratory viral infections                                                          Elkashif et al., Clinical & Translational Immunology 2021, October 12, 2021

The SARS-CoV-2 pandemic reflects the limitations of suboptimal capabilities in conventional vaccines. Conventional vaccines which use inactivated pathogens or attenuated pathogens are not suited for every pathogen and elicit only a modest, short-lived immune response. This study reviews new vaccine strategies using Ad-based vector-based vaccines in preclinical and clinical studies for current and emerging respiratory viruses, particularly coronaviruses, influenza viruses and respiratory syncytial viruses. Ad vectors are highly immunogenic and induce strong innate and adaptive immune responses that may assist in the development of broadly-protective vaccine platforms.

3. The Rise of Vectored Vaccines: A Legacy of the COVID-19 Global Crisis 
Danielle De Silve and Flavio De Fonseca, Vaccines, October 9, 2021

The crisis of COVID-19 created the window of opportunity for new emerging vaccine technologies. Prior to the pandemic, no viral vector vaccine had been considered for full human use, nonetheless was formulated through the global efforts of the scientific community with considerable success. Researchers from this study note the rapid response and delivery entails for in-depth review of the vaccines that emerged in the forefront of COVID-19. This systematic review assesses the prophylactic potential, particularities, and the expectations regarding the future of new adeno-associated vectors (immunogens ChaAdOx1, Sputnik, Convidecia (CanSino, Tianjin, China), and Janssen (Johnson & Johnson, New Jersey, EUA), in addition to other platforms such as Vaccinia virus MVA, influenza virus, and measles virus, among others for effective immunity.

4. Nanoparticles based on artificial self-assembling peptide and displaying M2e peptide and stalk HA epitopes of influenza A virus induce potent humoral and T-cell responses and protect against the viral infection 
Zykova et al., Nanomedicine: Nanotechnology, Biology and Medicine, October – January 2022

This study examines whether self-assembling nanoparticles carrying both M2e and HA2 induces antigen-specific multifunctional CD4+ effector memory T cells. Intranasal immunization of mice against the lethal challenge with different subtypes of influenza A virus were administered with and without additional adjuvants. Results obtained from self-assembling nanoparticles can be used to develop a universal influenza vaccine and further elucidate mechanisms for correlates of protection.

5. Universal TLR7-nanoparticle adjuvant promotes broad immune responses against heterologous strains of Influenza and SARS-CoV-2 [Pre-Print]
Yin et al., ResearchSquare, October 12, 2021

The need for broadly-protective influenza vaccines continue to echo in emerging literature. Though much has been learned from development of COVID-19 vaccines, challenges for influenza vaccines persist. Due to antigenic drift, seasonal influenza vaccines lack protection from circulating viruses on market. Scientists also note the role of adjuvants in enhancing vaccine induced immune responses, yet adjuvants that can improve vaccine responses has not been extensively studied. In this research study, scientists examined whether the TLR7-Np adjuvant could induce heterosubtypic influenza viruses via promotion of CD8 T cell responses which are otherwise rarely seen from conventional vaccine-induced immune responses. If successful, the TLR7-NP adjuvant may help lead to broader and more effective influenza virus or SARS-CoV-2 vaccines.

6. Fear of Influenza Resurgence amid COVID-19 Pandemic: Need for Effective Flu Vaccine Still Exists  
Wijesundara et al., Vaccines 2021, October 18, 2021

Despite global vaccination efforts, influenza-related mortality and morbidity occurs every year worldwide. This study provides several challenges and recommendations for enhancing vaccine interventions, including further study of optimal vaccine adjuvants to enhance humoral and T-cell immunity. In summary, this review includes eight highly relevant articles covering various aspects of influenza that will aid in the ongoing effort to develop a universal flu vaccine and minimize risk of influenza virus outbreaks.

7.  Adjuvanted trivalent influenza vaccine versus quadrivalent inactivated influenza vaccine in Hutterite Children: A randomized clinical trial 
Loeb et al., Vaccine, October 23, 2021

The potential direct and indirect benefits of adjuvanted influenza vaccination children is an important public health priority. Studies from longitudinal data suggests vaccination for influenza in children provides indirect benefits in community protection. In this study, researchers conducted a randomized controlled trial to test vaccinated children from the ages of 6 months to 6 years in Hutterite colonies withM59 adjuvanted influenza vaccine over three influenza seasons could reduce laboratory-confirmed influenza in children and their family clusters compared to unadjuvanted influenza vaccine.

8. Induction of trained immunity by influenza vaccination – Impact on COVID-19 
Debisarun et al., PLOS PATHOGENS, October 25, 2021

Recent studies have explored the potential link between influenza vaccination and decreased COVID-19 incidence and severity. This study assesses the association between influenza vaccination and COVID-19 incidence during the first two waves of the pandemic in the Netherlands, among employees of the Radboud University Medical Center (Radboudumc), a large academic hospital in effort to understand the potential beneficial effects on trained immunity.

9. Estimation of Reduction in Influenza Vaccine Effectiveness Due to Egg-Adaptation Changes—Systematic Literature Review and Expert Consensus 
Lejarazu-Leonardo et al., Vaccines, October 29, 2021

Influenza vaccines are the main tool to prevent morbidity and mortality of the disease; however, current approaches using egg-based manufacturing process may reduce their effectiveness compared to cell-based vaccines for Influenza A(H3N2). While virus antigenic drift cannot be controlled, egg adaptation changes may be potentially removed by the selection of technology that does not involve avian cells. The objective of this study was to quantify the impact of egg adaptations changes on the effectiveness of traditional trivalent and quadrivalent influenza vaccines in effort to discover more effective technologies for Influenza vaccines.

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