THE ANTIBODY RESPONSE OF HUMAN SUBJECTS VACCINATED WITH THE VIRUS OF HUMAN INFLUENZA

Intracellular Streptococcus pneumoniae develops enhanced fluoroquinolone persistence during influenza A coinfection

Streptococcus pneumoniae is a major pathogen responsible for severe complications in patients with prior influenza A virus (IAV) infection. We have previously demonstrated that S. pneumoniae exhibits increased intracellular survival within IAV-infected cells. Fluoroquinolones (FQs) are widely used to treat pneumococcal infections. However, our prior work has shown that S. pneumoniae can develop intracellular FQ persistence, a phenomenon triggered by oxidative stress within host cells. This persistence allows the bacteria to withstand high FQ concentrations. In this study, we show that IAV infection enhances pneumococcal FQ persistence during intracellular survival within pneumocytes, macrophages, and neutrophils. This enhancement is partly due to increased oxidative stress induced by the viral infection. We find that this phenotype is particularly pronounced in autophagy-proficient host cells, potentially resulting from IAV-induced blockage of autophagosome-lysosome fusion. Moreover, we identified several S. pneumoniae genes involved in oxidative stress response that contribute to FQ persistence, including sodA (superoxide dismutase), clpL (chaperone), nrdH (glutaredoxin), and psaB (Mn+2 transporter component). Our findings reveal a novel mechanism of antibiotic persistence promoted by viral infection within host cells. This underscores the importance of considering this phenomenon when using FQs to treat pneumococcal infections, especially in patients with concurrent influenza A infection.

Have Diagnostics, Therapies, and Vaccines Made the Difference in the Pandemic Evolution of COVID-19 in Comparison with "Spanish Flu"?

In 1918 many countries, but not Spain, were fighting World War I. Spanish press could report about the diffusion and severity of a new infection without censorship for the first-time, so that this pandemic is commonly defined as "Spanish flu", even though Spain was not its place of origin. "Spanish flu" was one of the deadliest pandemics in history and has been frequently compared with the coronavirus disease (COVID)-19 pandemic. These pandemics share similarities, being both caused by highly variable and transmissible respiratory RNA viruses, and diversity, represented by diagnostics, therapies, and especially vaccines, which were made rapidly available for COVID-19, but not for "Spanish flu". Most comparison studies have been carried out in the first period of COVID-19, when these resources were either not yet available or their use had not long started. Conversely, we wanted to analyze the role that the advanced diagnostics, anti-viral agents, including monoclonal antibodies, and innovative COVID-19 vaccines, may have had in the pandemic containment. Early diagnosis, therapies, and anti-COVID-19 vaccines have markedly reduced the pandemic severity and mortality, thus preventing the collapse of the public health services. However, their influence on the reduction of infections and re-infections, thus on the transition from pandemic to endemic condition, appears to be of minor relevance. The high viral variability of influenza and coronavirus may probably be contained by the development of universal vaccines, which are not easy to be obtained. The only effective weapon still remains the disease prevention, to be achieved with the reduction of promiscuity between the animal reservoirs of these zoonotic diseases and humans.

A protective measles virus-derived vaccine inducing long-lasting immune responses against influenza A virus H7N9

A novel Influenza A virus (subtype H7N9) emerged in spring 2013 and caused considerable mortality in zoonotically infected patients. To be prepared for potential pandemics, broadly effective and safe vaccines are crucial. Recombinant measles virus (MeV) encoding antigens of foreign pathogens constitutes a promising vector platform to generate novel vaccines. To characterize the efficacy of H7N9 antigens in a prototypic vaccine platform technology, we generated MeVs encoding either neuraminidase (N9) or hemagglutinin (H7). Moraten vaccine strain-derived vaccine candidates were rescued; they replicated with efficiency comparable to that of the measles vaccine, robustly expressed H7 and N9, and were genetically stable over 10 passages. Immunization of MeV-susceptible mice triggered the production of antibodies against H7 and N9, including hemagglutination-inhibiting and neutralizing antibodies induced by MV_vac2-H7(P) and neuraminidase-inhibiting antibodies by MV_vac2-N9(P). Vaccinated mice also developed long-lasting H7- and N9-specific T cells. Both MV_vac2-H7(P) and MV_vac2-N9(P)-vaccinated mice were protected from lethal H7N9 challenge.

Challenges of Making Effective Influenza Vaccines

Seasonal influenza vaccines prevent influenza-related illnesses, hospitalizations, and deaths. However, these vaccines are not as effective as other viral vaccines, and there is clearly room for improvement. Here, we review the history of seasonal influenza vaccines, describe challenges associated with producing influenza vaccine antigens, and discuss the inherent difficulties of updating influenza vaccine strains each influenza season. We argue that seasonal influenza vaccines can be dramatically improved by modernizing antigen production processes and developing models that are better at predicting viral evolution. Resources should be specifically dedicated to improving seasonal influenza vaccines while developing entirely new vaccine platforms.

Vaccination into the Dermal Compartment: Techniques, Challenges, and Prospects

In 2019, an 'influenza pandemic' and 'vaccine hesitancy' were listed as two of the top 10 challenges to global health by the WHO. The skin is a unique vaccination site, due to its immune-rich milieu, which is evolutionarily primed to respond to challenge, and its ability to induce both humoral and cellular immunity. Vaccination into this dermal compartment offers a way of addressing both of the challenges presented by the WHO, as well as opening up avenues for novel vaccine formulation and dose-sparing strategies to enter the clinic. This review will provide an overview of the diverse range of vaccination techniques available to target the dermal compartment, as well as their current state, challenges, and prospects, and touch upon the formulations that have been developed to maximally benefit from these new techniques. These include needle and syringe techniques, microneedles, DNA tattooing, jet and ballistic delivery, and skin permeabilization techniques, including thermal ablation, chemical enhancers, ablation, electroporation, iontophoresis, and sonophoresis.

The Future of Flu: A Review of the Human Challenge Model and Systems Biology for Advancement of Influenza Vaccinology

Objectives: Novel approaches to advance the field of vaccinology must be investigated, and are particularly of importance for influenza in order to produce a more effective vaccine. A systematic review of human challenge studies for influenza was performed, with the goal of assessing safety and ethics and determining how these studies have led to therapeutic and vaccine development. A systematic review of systems biology approaches for the study of influenza was also performed, with a focus on how this technology has been utilized for influenza vaccine development. Methods: The PubMed database was searched for influenza human challenge studies, and for systems biology studies that have addressed both influenza infection and immunological effects of vaccination. Results: Influenza human challenge studies have led to important advancements in therapeutics and influenza immunization, and can be performed safely and ethically if certain criteria are met. Many studies have investigated the use of systems biology for evaluating immune response to influenza vaccine, and several promising molecular signatures may help advance our understanding of pathogenesis and be used as targets for influenza interventions. Combining these methodologies has the potential to lead to significant advances in the field of influenza vaccinology and therapeutics. Conclusions: Human challenge studies and systems biology approaches are important tools that should be used in concert to advance our understanding of influenza infection and provide targets for novel therapeutics and immunizations.

Antibody levels in a cohort of pregnant women after the 2009 influenza A(H1N1) pandemic: Waning and association with self-reported severity and duration of illness

BACKGROUND

A population-based pregnancy cohort was established in Norway to study potential effects of exposure to the 2009 influenza pandemic or pandemic vaccination during pregnancy.

OBJECTIVES

We studied maternal A(H1N1)pdm09-specific hemagglutination inhibition (HI)-titer levels and waning in women with influenza-like illness (ILI) in pregnancy compared to vaccinated women. Moreover, we studied the association between HI-titers and self-reported severity and duration of ILI.

METHODS

HI-titers against the pandemic virus were measured in maternal blood samples obtained at birth, 3-9 months after exposure, and linked with information about pregnancy, influenza and vaccination from national registries and a cohort questionnaire.

RESULTS

Among 1821 pregnant women included, 43.7% were unvaccinated and 19.3% of these had ILI. HI-titers were low (geometric mean titer (GMT) 11.3) in the unvaccinated women with ILI. Higher HI-titers (GMT 37.8) were measured in the vaccinated women. Estimated HI-titer waning was similar for vaccinated women and women with ILI. Most ILI episodes were moderate and lasted 3-5 days. Women with ILI reporting specific influenza symptoms such as fever or cough had higher HI-titers than women without these symptoms. Women who reported being "very ill" or illness duration of >5 days had higher HI-titers than women reporting less severe illness or illness of shorter duration, respectively.

CONCLUSIONS

Antibody waning was similar in vaccinated women and women with ILI. More severe ILI or longer duration of illness was associated with higher HI-titers. Most unvaccinated pregnant women with ILI had low HI-titers, probably due to moderate illness and HI-titer waning between exposure and sampling.

Influenza vaccination and the 'diversity paradox'

The antigenic evolution of influenza is widely assumed to occur by antigenic drift, in which strains incrementally acquire mutations in highly variable epitopes under strong immune selective pressure, such as those in the major influenza antigen haemagglutinin. However, this is not easy to reconcile with epidemiological observations, which show that each influenza season is dominated by a limited number of strains. Here, we discuss this paradox in light of recent influenza epidemics that have been characterised by low vaccine effectiveness and dominated by strains of limited antigenic and genetic diversity.

Immunogenicity, safety and tolerability of intradermal influenza vaccines

Intradermal influenza vaccination has been studied for more than 80 y. The revived interest in this strategy of vaccination is a result of the innovative technologies in needle design allowing more precise injection and making the device easier to use. Furthermore, clinical trials on these novel devices have demonstrated significant dose sparing effects, improved immunogenicity and very few adverse effects. This review compares intradermal vaccination with various devices with subcutaneous and intramuscular vaccination. We also discussed the role of topical adjuvant before intradermal vaccination.

Antibody Responses to Trivalent Inactivated Influenza Vaccine in Health Care Personnel Previously Vaccinated and Vaccinated for The First Time

Inactivated influenza vaccination induces a hemagglutinin-specific antibody response to the strain used for immunization. Annual vaccination is strongly recommended for health care personnel. However, it is debatable if repeated vaccination would affect the antibody response to inactivated influenza vaccine through the time. We enrolled health care personnel who had repeated and first trivalent inactivated influenza vaccination in 2005–2008. Serological antibody responses were measured by hemagglutination-inhibition (HI) test. Subjects with repeated vaccination had higher pre-vaccination and lower post-vaccination HI titer than those with first vaccination, although serological responses between groups might vary with different antigen types and while the drifted strain was introduced in the vaccine. Higher fold rise in the HI titer was observed in the group with first than repeated vaccination and the fold increase in the HI titer was inversely correlated with pre-vaccination titer in 2007 and 2008. Nevertheless, no significant difference in the day 28 seroprotection rate was observed between groups with repeated and first vaccination in most circumstances. Further studies are needed to understand the long-term effect of repeated vaccination on the antibody response both at the serological and repertoire levels among health care personnel.

Fluzone® Intradermal Quadrivalent Influenza Vaccine

INTRODUCTION

An intradermal version of Fluzone® split-virion inactivated trivalent influenza vaccine, containing 9 µg hemagglutinin per strain of A/H1N1, A/H3N2, and one B lineage virus (Fluzone Intradermal, Sanofi Pasteur), became available in the US during the 2011-2012 influenza season for adults 18-64 years of age. In advance of the 2015-2016 season, Fluzone Intradermal was replaced with Fluzone Intradermal Quadrivalent vaccine, which contains 9 µg hemagglutinin per strain of the two A-strain viruses and both B-strain lineage viruses (Victoria and Yamagata).

AREAS COVERED

This literature review summarizes the history and mechanism of intradermal vaccination, discusses the clinical trial results supporting the immunogenicity and safety of Fluzone Intradermal Quadrivalent vaccine, and describes the unique microinjection system used to deliver Fluzone Intradermal Quadrivalent. Expert commentary: Fluzone Intradermal Quadrivalent may boost confidence in influenza vaccination with the addition of a second B-lineage strain. By using an innovative microinjection system, the vaccine is also designed to address some of the logistic challenges faced by healthcare providers administering immunizations.

Anti-Infectious Human Vaccination in Historical Perspective

A brief history of vaccination is presented since the Jenner's observation, through the first golden age of vaccinology (from Pasteur's era to 1938), the second golden age (from 1940 to 1970), until the current period. In the first golden age, live, such as Bacille Calmette Guérin (BCG), and yellow fever, inactivated, such as typhoid, cholera, plague, and influenza, and subunit vaccines, such as tetanus and diphtheria toxoids, have been developed. In the second golden age, the cell culture technology enabled polio, measles, mumps, and rubella vaccines be developed. In the era of modern vaccines, in addition to the conjugate polysaccharide, hepatitis A, oral typhoid, and varicella vaccines, the advent of molecular biology enabled to develop hepatitis B, acellular pertussis, papillomavirus, and rotavirus recombinant vaccines. Great successes have been achieved in the fight against infectious diseases, including the smallpox global eradication, the nearly disappearance of polio, the control of tetanus, diphtheria, measles, rubella, yellow fever, and rabies. However, much work should still be done for improving old vaccines, such as BCG, anthrax, smallpox, plague, or for developing effective vaccines against old or emerging infectious threats, such as human-immunodeficiency-virus, malaria, hepatitis C, dengue, respiratory-syncytial-virus, cytomegalovirus, multiresistant bacteria, Clostridium difficile, Ebola virus. In addition to search for innovative and effective vaccines and global infant coverage, even risk categories should adequately be protected. Despite patients under immunosuppressive therapy are globally increasing, their vaccine coverage is lower than recommended, even in developed and affluent countries.

Intradermal vaccination using the novel microneedle device MicronJet600: Past, present, and future

Intradermal immunization has become a forefront of vaccine improvement, both scientifically and commercially. Newer technologies are being developed to address the need to reduce the dose required for vaccination and to improve the reliability and ease of injection, which have been major hurdles in expanding the number of approved vaccines using this route of administration. In this review, 7 y of clinical experience with a novel intradermal delivery device, the MicronJet600, which is a registered hollow microneedle that simplifies the delivery of liquid vaccines, are summarized. This device has demonstrated both significant dose-sparing and superior immunogenicity in various vaccine categories, as well as in diverse subject populations and age groups. These studies have shown that intradermal delivery using this device is safe, effective, and preferred by the subjects. Comparison with other intradermal devices and potential new applications for intradermal delivery that could be pursued in the future are also discussed.

Skin immunization with influenza vaccines

Problems with existing influenza vaccines include the strain specificity of the immune response, resulting in the need for frequent reformulation in response to viral antigenic drift. Even in years when the same influenza strains are prevalent, the duration of immunity is limited, and results in the need for annual revaccination. The immunogenicity of the present split or subunit vaccines is also lower than that observed with whole inactivated virus, and the vaccines are not very effective in high risk groups such as the young or the elderly. Vaccine coverage is incomplete, due in part to concerns about the use of hypodermic needles for delivery. Alternative approaches for vaccination are being developed which address many of these concerns. Here we review new approaches which focus on skin immunization, including the development of needle-free delivery systems which use stable dry formulations and induce stronger and longer-lasting immune responses.

Intanza (®) 9 µg intradermal seasonal influenza vaccine for adults 18 to 59 years of age

Seasonal influenza in healthy working-age adults accounts for a substantial part of the socioeconomic burden of this disease. Intanza® 9 µg (sanofi pasteur) is a microneedle-delivered intradermal trivalent inactivated influenza vaccine approved in 2009 for the prevention of seasonal influenza in adults 18 to 59 years of age. The microneedle system reliably and reproducibly delivers the vaccine to the dermis. Clinical studies show that Intanza 9 µg is as immunogenic and as well tolerated in working-age adults as a reference intramuscular trivalent inactivated vaccine. Local reactions to Intanza 9 µg, mainly erythema, are transient, mostly mild or moderate, and do not affect acceptability. Intanza 9 µg is considered satisfactory by at least 95% of both vaccinees and prescribers, especially because of the short needle and rapid administration. Because Intanza® 9 µg offers an alternative to intramuscular vaccines, it might help increase influenza vaccine coverage rates.

Influenza vaccination for older adults

Influenza vaccines were developed in the 1930s and were shown in randomized clinical trials to prevent influenza in young healthy adults. The significant morbidity and mortality associated with influenza in adults, age 65 y and older, prompted the early recommendation for influenza vaccination in that age group, based on efficacy data in younger adults. Subsequently a number of studies have demonstrated vaccine effectiveness in older adults, but it appears to be lower than in younger adults. New vaccines are being developed with enhanced immunogenicity to improve the protection of older adults. In the meantime, the currently licensed influenza vaccines need to be administered annually to prevent the estimated 90,000 hospitalizations and 5,000 deaths attributed to influenza in adults ≥65 y of age each year.

Changes in human Langerhans cells following intradermal injection of influenza virus-like particle vaccines

There is a significant gap in our fundamental understanding of early morphological and migratory changes in human Langerhans cells (LCs) in response to vaccine stimulation. As the vast majority of LCs studies are conducted in small animal models, substantial interspecies variation in skin architecture and immunity must be considered when extrapolating the results to humans. This study aims to determine whether excised human skin, maintained viable in organ culture, provides a useful human model for measuring and understanding early immune response to intradermally delivered vaccine candidates. Excised human breast skin was maintained viable in air-liquid-interface organ culture. This model was used for the first time to show morphological changes in human LCs stimulated with influenza virus-like particle (VLP) vaccines delivered via intradermal injection. Immunohistochemistry of epidermal sheets and skin sections showed that LCs in VLP treated skin lost their typical dendritic morphology. The cells were more dispersed throughout the epidermis, often in close proximity to the basement membrane, and appeared vertically elongated. Our data provides for increased understanding of the complex morphological, spatial and temporal changes that occur to permit LC migration through the densely packed keratinocytes of the epidermis following exposure to vaccine. Significantly, the data not only supports previous animal data but also provides new and essential evidence of host response to this vaccination strategy in the real human skin environment.

ANTIBODY RESPONSE OF HUMAN BEINGS FOLLOWING VACCINATION WITH INFLUENZA VIRUSES

Eleven different preparations of influenza virus were used to vaccinate large groups of human beings. The antibody response to these vaccines was measured by means of the in vitro agglutination inhibition test, and the geometric mean titers of sera taken 2 weeks after vaccination were compared. From these comparisons the following conclusions were drawn: 1. There was a wide individual variation in the antibody response of human beings to the same preparation of influenza virus administrated subcutaneously. The amount of antibody produced by a group with a low prevaccination antibody level was very nearly the same as the amount produced by groups that had higher initial levels. 2. The use of the X strain of distemper virus in the preparation of an influenza vaccine did not enhance the antigenicity of the influenza virus present. 3. Within certain limits the mean antibody response of human beings increased as the amount of virus injected was increased. When large amounts of influenza A virus were given, the antibody response was of the same order of magnitude as that which occurred following actual infection by this virus. 4. When the vaccine was prepared from allantoic fluid, there was no significant difference in the antibody response of human beings given active virus, formalin-inactivated virus, heat-inactivated virus, or virus inactivated by the drying process. 5. Ground infected chick embryos, when diluted with infected allantoic fluid, gave a greater antibody response than allantoic fluid alone (when the virus remained active). The antigenicity of such a preparation was diminished when the virus was inactivated by formalin. 6. Antibody levels 6 and 9 weeks after vaccination showed a marked drop from the 2-week postvaccination levels. In a small group the antibody levels at 5 months were still further reduced. Those individuals who possessed the higher titers tended to lose their antibodies faster than did those at a lower level.

A COMPLEX VACCINE AGAINST INFLUENZA A VIRUS : QUANTITATIVE ANALYSIS OF THE ANTIBODY RESPONSE PRODUCED IN MAN

A quantitative study of the antigenicity of various vaccines containing influenza A virus has been made in human beings. A complex vaccine prepared from chick embryos inoculated with both influenza A virus and the X strain of canine distemper virus was found to be more effective than other vaccines in stimulating the production of neutralizing antibodies against the former virus. The increased antibody levels which resulted from the administration of this vaccine remained almost unaltered for at least 5 months.

THE DEMONSTRATION OF LESIONS AND VIRUS IN THE LUNGS OF MICE RECEIVING LARGE INTRA-PERITONEAL INOCULATIONS OF EPIDEMIC INFLUENZA VIRUS

Following the intraperitoneal inoculation of mice with large doses of epidemic influenza virus (50,000 to 1 million intranasal M.L.D.) it can be recovered from the lungs in high concentration, and pulmonary lesions of moderate extent may be observed. The virus reaches its highest titer in the lungs 48 to 72 hours after intraperitoneal injection and may persist for 10 days. Virus may be recovered from the blood in the first 24 hours, but is readily detected in the omentum and peritoneum for 5 to 6 days. Mice which as a result of the intraperitoneal injection of virus show a high concentration of virus in the lungs do not die but become solidly immune to intranasal infection. Moreover, as early as 24 to 48 hours after intraperitoneal inoculation of large amounts of virus the animals may exhibit resistance to infection with fatal doses of virus given intranasally. Influenza virus given intravenously to mice is rapidly removed from the blood but persists in the lungs and induces pulmonary lesions. Virus can also be recovered from the liver for several days. With subcutaneous inoculation of influenza virus, however, the virus does not reach the blood or lungs in detectable amounts although the regional lymph nodes may yield considerable quantities of the agent. A brief consideration is presented of the mechanisms of infection and resistance which may be involved.

QUANTITATIVE RELATIONSHIPS BETWEEN THE IMMUNIZING DOSE OF EPIDEMIC INFLUENZA VIRUS AND THE RESULTANT IMMUNITY

A direct proportion exists between the concentration of epidemic influenza virus used for intraperitoneal immunization of mice and the degree of immunity to intranasal infection which develops. Mice vaccinated with virus of a given strength resist infection with virus of the same concentration but not more. An irreducible minimum exists since mice vaccinated with less than ten intranasal lethal doses do not develop sufficient immunity to overcome intranasal infection with virus of the same strength. The fact that there exists a limiting threshold for the degree of immunity which a certain strength of virus will induce indicates that the virus does not multiply after intraperitoneal inoculations. In ferrets a state of partial immunity is induced as a result of subcutaneous vaccination with active influenza virus. Vaccination with doses containing 100 or more intranasal infectious units is required for the production of circulating antibodies, protection of the animals from pulmonary involvement, and modification of the severity of the disease. On the other hand, intranasal inoculation with one infectious unit results in a firm, immediate immunity, although the duration of immunity may bear a relation to the severity of the original infection and consequently to the size of the infecting dose. Ferrets in a state of partial immunity resulting from subcutaneous vaccination, or from the waning of a firm immunity following infection, respond to intranasal inoculation of influenza virus with an accelerated production of neutralizing antibodies. The antibody titer under these conditions reaches a much higher level than occurs following a primary infection. Fully immune animals, however, show no further antibody response to a second inoculation.

THE PREPARATION AND PROPERTIES OF INFLUENZA VIRUS VACCINES CONCENTRATED AND PURIFIED BY DIFFERENTIAL CENTRIFUGATION

Influenza virus vaccines containing from 1 to 10 mg. of virus materials per cc. concentrated and purified from infectious allantoic fluids by means of one or two cycles of differential centrifugation and inactivated by different treatments have been prepared and subjected to laboratory tests. Suitable inactivation of the virus preparations with retention of full red cell agglutinating activity and immunizing potency in mice was achieved by treatment with minimal amounts of formaldehyde or ultraviolet light. Treatment with phenol or chloroform failed to cause adequate loss of virus activity. Excessive amounts of formaldehyde or of ultraviolet light were found to cause a loss in red cell agglutinating activity and in immunizing potency. Freezing resulted in the immediate loss of red cell agglutinating activity of the formalinized vaccine. Storage of the vaccines in the frozen state was accompanied by a gradual decrease in red cell agglutinating activity. Drying of the vaccines from the frozen state resulted in a loss of red cell agglutinating activity and, in the case of the formalinized vaccine, in a loss in immunizing potency. There appeared to be at least a rough correlation between red cell agglutinating activity and immunizing potency. The immunizing potency and red cell agglutinating activity of a purified formalinized vaccine containing 2 mg. of virus material per cc. were unchanged following 2 months' storage at 4 degrees but were measurably decreased following storage for 2 months at 18 to 25 degrees and at 37 degrees . At equivalent dosages of virus material the immunizing potency of formalinized centrifugally purified virus, of formalinized virus purified by the red cell elution method, and of infectious allantoic fluid was not measurably different. The immunizing potency of a formalinized polyvalent vaccine containing centrifugally purified Lee, PR8, and Weiss influenza virus materials at concentrations of 5, 2.5, and 2.5 mg. per cc., respectively, was found to be essentially the same as that of a similar vaccine prepared commercially. In both cases the protection afforded against the Weiss strain appeared to be better than that against the Lee and PR8 strains. The commercially prepared vaccine is being subjected to clinical tests in man at dosage levels ranging from 0.01 mg. to 10 mg. The latter corresponds to a level approximately 100 times that of infectious allantoic fluid. It was found that the bacterial contamination that frequently accompanies operation on a large scale can be controlled by the addition of one part per 10,000 of formalin plus one part per 100,000 of phenyl mercuric nitrate to the allantoic fluid immediately following harvesting, without affecting the quality of the vaccine. This procedure and the use of virus materials purified and concentrated by a single cycle of differential centrifugation by means of the Sharples centrifuge were found to be suitable for the production of influenza virus vaccines on a large scale. By means of this method influenza vaccines possessing 20 or more times the immunizing potency of infectious allantoic fluid and 10 or more times the immunizing potency of the usual commercial vaccine prepared by the red cell elution method can be manufactured rapidly on a very large scale with considerable ease and efficiency.

A phase I evaluation of inactivated influenza A/H5N1 vaccine administered by the intradermal or the intramuscular route

In a phase I clinical trial, one hundred healthy young adults were randomized to receive two doses 28 days apart of an inactivated, subvirion vaccine containing 15 or 45microg of influenza A/H5N1 hemagglutinin (HA) by the intramuscular (IM) route, or 3 or 9microg of H5 HA by the intradermal(ID) route. Seventy-seven subjects received a third dose. All regimens were safe and well tolerated. Antibody responses after two or three doses were low (<or=20% or <or=38%, respectively) and similar in groups given 3 or 9microg ID or 15microg IM, and were significantly lower than those given 45microg IM. Higher dosages of H5 HA and/or inclusion of adjuvant will be required to enhance immunogenicity by the ID route.

Safety and efficacy of a novel microneedle device for dose sparing intradermal influenza vaccination in healthy adults

BACKGROUND

Intradermal vaccine delivery has been shown to induce good immune responses with low vaccine doses. Technologies for drug-delivery which specifically target the skin may render intradermal vaccination more accessible.

METHODS

We conducted a prospective, randomized trial in 180 intended-to-treat healthy adults. Study objectives were to evaluate the safety and immunogenicity of low-dose intradermal (ID) influenza vaccines delivered using a novel microneedle device (MicronJet). This device replaces a conventional needle, and is designed specifically for intradermal delivery. Subjects were randomly assigned to receive either the full-dose standard flu shot (containing 15 microg hemagglutinin per strain) delivered intramuscularly using a conventional needle (IM group), a medium dose intradermal injection (6 microg hemagglutinin per strain) delivered with the MicronJet (ID2 group), or a low-dose intradermal injection (3 microg hemagglutinin per strain) delivered with the MicronJet (ID1 group). A marketed influenza vaccine for the 2006/2007 influenza season (alpha-RIX by GSK Biologicals) was used for all injections. Adverse events were recorded over a 42-day period. Immunogenicity was evaluated by changes in hemagglutination inhibition (HAI) antibody titer, and by comparing geometric mean titers (GMTs), seroconversion, and seroprotection rates between the study groups.

RESULTS

Local reactions were significantly more frequent following intradermal vaccination, but were mild and transient in nature. At 21 days after injection, GMT fold increase was 22, 18 and 22 in the ID1, ID2 and IM groups respectively for the H1N1 strain; 9, 9 and 16 for the H3N2 strain and 9, 13 and 11 for strain B. The CPMP criteria for re-licensure of seasonal influenza vaccines were met in full for all study groups.

CONCLUSIONS

Low-dose influenza vaccines delivered intradermally using microneedles elicited immunogenic responses similar to those elicited by the full-dose intramuscular vaccination. The microneedle injection device used in this study was found to be effective, safe, and reliable.

Intradermal vaccine delivery: will new delivery systems transform vaccine administration?

There has been a recent resurgence of interest in intradermal vaccine delivery. The physiological advantages of intradermal vaccine delivery have been known for some time, but the difficulties associated with performing an intradermal injection have historically limited its use. New delivery systems currently in development facilitate convenient intradermal vaccination, unlocking the potential advantages of this delivery route, and potentially transforming vaccine delivery.

Discovery and characterization of the 1918 pandemic influenza virus in historical context

The 2005 completion of the entire genome sequence of the 1918 H1N1 pandemic influenza virus represents both a beginning and an end. Investigators have already begun to study the virus in vitro and in vivo to better understand its properties, pathogenicity, transmissibility and elicitation of host responses. Although this is an exciting new beginning, characterization of the 1918 virus also represents the culmination of over a century of scientific research aiming to understand the causes of pandemic influenza. In this brief review we attempt to place in historical context the identification and sequencing of the 1918 virus, including the alleged discovery of a bacterial cause of influenza during the 1889-1893 pandemic, the controversial detection of 'filter-passing agents' during the 1918-1919 pandemic, and subsequent breakthroughs in the 1930s that led to isolation of human and swine influenza viruses, greatly influencing the development of modern virology.

Discovery and Characterization of the 1918 Pandemic Influenza Virus in Historical Context

The 2005 completion of the entire genome sequence of the 1918 H1N1 pandemic influenza virus represents both a beginning and an end. Investigators have already begun to study the virus in vitro and in vivo to better understand its properties, pathogenicity, transmissibility and elicitation of host responses. Although this is an exciting new beginning, characterization of the 1918 virus also represents the culmination of over a century of scientific research aiming to understand the causes of pandemic influenza. In this brief review we attempt to place in historical context the identification and sequencing of the 1918 virus, including the alleged discovery of a bacterial cause of influenza during the 1889–1893 pandemic, the controversial detection of ‘filter-passing agents’ during the 1918–1919 pandemic, and subsequent breakthroughs in the 1930s that led to isolation of human and swine influenza viruses, greatly influencing the development of modern virology.

A comparison of the intradermal and subcutaneous routes of influenza vaccination with A/New Jersey/76 (swine flu) and A/Victoria/75: report of a study and review of the literature

A trail of influenza vaccination, with use of bivalent split virus vaccine (A/New Jersey/76 and A/Victoria/75), was conducted to compare the immunogenicity and reactions when vaccine was given by the subcutaneous and intradermal routes. Volunteers 18 to 24 years old were randomized into equal groups, one group receiving 0.1 ml of vaccine intradermally and the other receiving 0.5 ml subcutaneously. For the A/Victoria vaccine, the immunogenicity of the intradermal route seemed superior; for A/New Jersey vaccine, the routes were equivalent. Adverse reactions were minimal and equivalent for both groups. In times of vaccine shortage, the intradermal route is considered to stretch vaccine supplies. Field trials of new influenza vaccines should include evaluation of the immunogenicity of and adverse reactions caused by the same vaccine given by different routes in varied dosages.

The search for the ideal influenza vaccine

The history of the development of influenza virus vaccine is traced from its origin with experimental studies of influenza virus in ferrets and mice and the first trials in man. Knowledge of the basis of immunity to the viruses in experimental animals and in man has grown steadily over the years and has been essential to successful immunization. Virus variation affecting the surface antigens of the virus is seen as the principal obstacle to the application of vaccines in man. So significant are the changes occurring during antigenic drift that former concepts of a polyvalent vaccine cannot provide a solution of the problem of the composition of vaccines. Disrupted virus vaccines appear to provide the answer to the prevention of vaccine reactions.

An assessment of oil adjuvant and aqueous influenza vaccines. I. Reactions to the vaccines

Trials of aqueous and oil adjuvant vaccines in young adult volunteers showed that severe local reactions were rare. However, the incidence of minor symptoms was too high for a vaccine which requires to be administered repeatedly. In contradistinction to some reports, systemic and allergic reactions did not constitute a problem.

Vaccination against influenza

This paper reviews studies which have been carried out during the past twenty years in the United States of America to investigate the suitability of various vaccines and vaccination methods for immunizing man against the different influenza virus strains. A number of investigations in closed communities, such as children's institutions, army and navy units, and medical schools, are described. The author discusses the comparative value of the techniques employed in preparing vaccines, and the use of adjuvants in improving the response.