Report on the first WHO integrated meeting on development and clinical trials of influenza vaccines that induce broadly protective and long-lasting immune responses: Hong Kong SAR, China, 24-26 January 2013

Current trends in targeted therapy for drug-resistant infections

Escalating antibiotic resistance is now a serious menace to global public health. It may be led to the emergence of "postantibiotic age" in which most of infections are untreatable. At present, there is an essential need to explore novel therapeutic strategies as a strong and sustainable pipeline to combat antibiotic-resistant infections. This review focuses on recent advances in this area including therapeutic antibodies, antimicrobial peptides, vaccines, gene therapy, genome editing, and phage therapy for tackling drug-resistant infections.

Vector optimization and needle-free intradermal application of a broadly protective polyvalent influenza A DNA vaccine for pigs and humans

The threat posed by the 2009 pandemic H1N1 virus emphasized the need for new influenza A virus vaccines inducing a broad cross-protective immune response for use in both humans and pigs. An effective and broad influenza vaccine for pigs would greatly benefit the pork industry and contribute to public health by diminishing the risk of emerging highly pathogenic reassortants. Current inactivated protein vaccines against swine influenza produce only short-lived immunity and have no efficacy against heterologous strains. DNA vaccines are a potential alternative with advantages such as the induction of cellular and humoral immunity, inherent safety and rapid production time. We have previously developed a DNA vaccine encoding selected influenza proteins of pandemic origin and demonstrated broad protective immune responses in ferrets and pigs. In this study, we evaluated our DNA vaccine expressed by next-generation vectors. These new vectors can improve gene expression, but they are also efficiently produced on large scales and comply with regulatory guidelines by avoiding antibiotic resistance genes. In addition, a new needle-free delivery of the vaccine, convenient for mass vaccinations, was compared with intradermal needle injection followed by electroporation. We report that when our DNA vaccine is expressed by the new vectors and delivered to the skin with the needle-free device in the rabbit model, it can elicit an antibody response with the same titers as a conventional vector with intradermal electroporation. The needle-free delivery is already in use for traditional protein vaccines in pigs but should be considered as a practical alternative for the mass administration of broadly protective influenza DNA vaccines.

Universal influenza vaccines: a realistic option?

The extensive antigenic drift displayed by seasonal influenza viruses and the risk of pandemics caused by newly emerging antigenically distinct influenza A viruses of novel subtypes has raised considerable interest in the development of so-called universal influenza vaccines. We review options for the development of universal flu vaccines and discuss progress that has been made recently.

Report on the second WHO integrated meeting on development and clinical trials of influenza vaccines that induce broadly protective and long-lasting immune responses: Geneva, Switzerland, 5-7 May 2014

On 5-7 May 2014, the World Health Organization (WHO) convened the second integrated meeting on "influenza vaccines that induce broadly protective and long-lasting immune responses". Around 100 invited experts from academia, the vaccine industry, research and development funders, and regulatory and public health agencies attended the meeting. Areas covered included mechanisms of protection in natural influenza-virus infection and vaccine-induced immunity, new approaches to influenza-vaccine design and production, and novel routes of vaccine administration. A timely focus was on how this knowledge could be applied to both seasonal influenza and emerging viruses with pandemic potential such as influenza A (H7N9), currently circulating in China. Special attention was given to the development of possible universal influenza vaccines, given that the Global Vaccine Action Plan calls for at least one licensed universal influenza vaccine by 2020. This report highlights some of the topics discussed and provides an update on studies published since the report of the previous meeting.

Safety, immunogenicity and infectivity of new live attenuated influenza vaccines

Live attenuated influenza vaccines (LAIVs) are believed to be immunologically superior to inactivated influenza vaccines, because they can induce a variety of adaptive immune responses, including serum antibodies, mucosal and cell-mediated immunity. In addition to the licensed cold-adapted LAIV backbones, a number of alternative LAIV approaches are currently being developed and evaluated in preclinical and clinical studies. This review summarizes recent progress in the development and evaluation of LAIVs, with special attention to their safety, immunogenicity and infectivity for humans, and discusses their perspectives for the future.

Application of the screening method to monitor influenza vaccine effectiveness among the elderly in Germany

Background

Elderly people are at increased risk for severe influenza illness and constitute therefore a major target-group for seasonal influenza vaccination in most industrialized countries. The aim of this study was to estimate influenza vaccine effectiveness (VE) among individuals aged 60+ years over three seasons and to assess if the screening method is a suitable tool to monitor influenza VE in this particular target-group in Germany.

Methods

We identified laboratory-confirmed influenza cases aged 60+ years through the national communicable disease reporting system for seasons 2010/11, 2011/12 and 2012/13. Vaccination coverage (VC) data were retrieved from a database of health insurance claims representing ~85% of the total German population. We applied the screening method to calculate influenza subtype-specific VE and compared our results with VE estimates from other observational studies in Europe.

Results

In total, 7,156 laboratory-confirmed influenza cases were included. VE against all influenza types ranged between 49% (95% confidence interval [CI]: 39–56) in 2011/12 and 80% (95% CI: 76-83%) in 2010/11. In 2010/11 subtype-specific VE against influenza A(H1N1)pdm and B was 76% and 84%, respectively. In the following seasons, VE against influenza A(H1N1)pdm, A(H3N2) and B was 87%, -9% , 74% (2011/12), and 74%, 39%, 73% (2012/13). VE was higher among hospitalized compared to non-hospitalized influenza A cases. Seventeen observational studies from Europe reporting subtype-specific VE among the elderly were identified for the respective seasons (all applying the test-negative design) and showed comparable subtype-specific VE estimates.

Conclusions

According to our study, influenza vaccination provided moderate protection against laboratory-confirmed influenza A(H1N1)pdm and B in individuals aged 60+ but no or only little protection against A(H3N2). Higher VE among hospitalized cases might indicate higher protection against severe influenza disease. Based on the available data, the screening method allowed us to assess subtype-specific VE in hospitalized and non-hospitalized elderly persons. Since controlling for several important confounders was not possible, the applied method only provided crude VE estimates. However, given the precise VC-data and the large number of cases, the screening method provided results being in line with VE estimates from other observational studies in Europe that applied a different study design.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0882-3) contains supplementary material, which is available to authorized users.

Influenza vaccines: an Asia-Pacific perspective

This article provides an overview of some aspects of seasonal, pre-pandemic and pandemic influenza vaccines and initiatives aimed to increase influenza vaccine use within the Asia-Pacific region. Expanding the use of influenza vaccines in the Asia-Pacific region faces many challenges. Despite the recent regional history for the emergence of novel viruses, SARS, the H5N1 and H7N9, and the generation of and global seeding of seasonal influenza viruses and initiatives by WHO and other organisations to expand influenza awareness, the use of seasonal influenza vaccines remains low. The improvement in current vaccine technologies with the licensing of quadrivalent, live-attenuated, cell culture-based, adjuvanted and the first recombinant influenza vaccine is an important step. The development of novel influenza vaccines able to provide improved protection and with improved manufacturing capacity is also advancing rapidly. However, of ongoing concern are seasonal influenza impact and the low use of seasonal influenza vaccines in the Asia-Pacific region. Improved influenza control strategies and their implementation in the region are needed. Initiatives by the World Health Organization (WHO), and specifically the Western Pacific Regional Office of WHO, are focusing on consistent vaccine policies and guidelines in countries in the region. The Asian-Pacific Alliance for the Control of Influenza (APACI) is contributing through the coordination of influenza advocacy initiates.

Fast vaccine design and development based on correlates of protection (COPs)

New and reemerging infectious diseases call for innovative and efficient control strategies of which fast vaccine design and development represent an important element. In emergency situations, when time is limited, identification and use of correlates of protection (COPs) may play a key role as a strategic tool for accelerated vaccine design, testing, and licensure. We propose that general rules for COP-based vaccine design can be extracted from the existing knowledge of protective immune responses against a large spectrum of relevant viral and bacterial pathogens. Herein, we focus on the applicability of this approach by reviewing the established and up-coming COPs for influenza in the context of traditional and a wide array of new vaccine concepts. The lessons learnt from this field may be applied more generally to COP-based accelerated vaccine design for emerging infections.

Prevention and Control of Influenza Viruses

The 2003–2004 outbreaks of highly pathogenic avian influenza (HPAI) have proven to be disastrous to the regional poultry industry in Asia, and have raised serious worldwide public health apprehension regarding the steps that should be taken to urgently control HPAI. Control measures must be taken based on the principles of biosecurity and disease management and at the same time making public aware of the precautionary measures at the verge of outbreak. Creation of protection and surveillance zones, various vaccination strategies viz. routine, preventive, emergency, mass and targeted vaccination programmes using live, inactivated and recombinant vaccines are the common strategies adopted in different parts of the globe. The new generation vaccines include recombinant vaccines and recombinant fusion vaccine. The pro-poor disease control programmes, giving compensation and subsidies to the farmers along with effective and efficient Veterinary Services forms integral part of control of HPAI. Following biosecurity principles and vaccination forms integral part of control programme against swine and equine influenza as well. Use of neuraminidase (NA) inhibitors (Zanamivir and Oseltamivir) for the treatment of human influenza has been widely accepted worldwide. The threat of increasing resistance of the flu viruses to these antivirals has evoked interest in the development of novel antiviral drugs for influenza virus such as inhibitors of cellular factors and host signalling cascades, cellular miRNAs, siRNA and innate immune peptides (defensins and cathelicidins). Commercial licensed inactivated vaccines for humans against influenza A and B viruses are available consisting of three influenza viruses: influenza type A subtype H3N2, influenza type A subtype H1N1 (seasonal) virus strain and influenza type B virus strain. As per WHO, use of tetravaccine consisting of antigens of influenza virus serotypes H3N2, H1N1, B and H5 is the most promising method to control influenza pandemic. All healthy children in many countries are required to be vaccinated between 6 and 59 months of age. The seasonal vaccines currently used in humans induce strain-specific humoral immunity as the antibodies. Universal influenza virus vaccines containing the relatively conserved ectodomain of M2 (M2e), M1, HA fusion peptide and stalk domains, NA, NP alone or in combination have been developed which have been shown to induce cross-protection. The T cell-based vaccines are another recent experimental approach that has been shown to elicit broad-spectrum heterosubtypic immunity in the host. As far as HPAI is concerned, various pandemic preparedness strategies have been documented.

Broadly neutralizing antibodies and the promise of universal vaccines: where are we now?

Recent research has provided strong support for the utility of broadly neutralizing antibodies generated against viruses, which inherently possess a high degree of antigenic variability (such as influenza virus or HIV) as a feasible means to prevent infection. Many of these antibodies share the ability to bind to highly conserved regions within the stem of the virus ‘spike’ or surface glycoprotein, in such a way that they interfere with virus entry, including membrane fusion. As a result, broadly neutralizing antibodies could be supplied to patients as a form of passive immunotherapy, as well as play a role in the design of new ‘universal’ vaccines and antiviral agents. The following article describes the most recent innovations in this exciting field.

Addressing the public health burden of respiratory viruses: the Battle against Respiratory Viruses (BRaVe) Initiative

Given the enormous estimated burden of respiratory virus infections worldwide, a substantial number of research priorities exist in order to better understand their epidemiology, pathogenesis, prevention and clinical management across different populations and resource settings. New therapeutics and specific vaccines for noninfluenza respiratory virus infections could provide enormous benefits in reducing the morbidity and mortality associated with these frequent infections and provide the foundation for responding to newly emerging threats. The BRaVe Initiative is a new WHO-led effort to catalyze multidisciplinary research on strategies to prevent and treat medically important respiratory virus infections with the goal of timely integration of scientific advances and technical innovations into public health practice.