Effectiveness of live, attenuated intranasal influenza virus vaccine in healthy, working adults: a randomized controlled trial

Current status of live attenuated influenza virus vaccine in the US

The efficacy and effectiveness of cold adapted live attenuated (CAIV-T, FluMist intranasal influenza vaccine is reviewed. CAIV-T consists of approximately 10(7) TCID50 per dose of each influenza A/H1N1, influenza A/H3N2, and influenza B vaccine strain. The exact strains are updated each year to antigenically match the antigens recommended by national health authorities for inclusion in the vaccine. In one year in which the vaccine strain did not well match the epidemic strain, the live attenuated vaccine induced a broad immune response that cross-reacted significantly with the drifted strain. The efficacy of CAIV-T in adults was demonstrated with challenge studies and the effectiveness of the vaccine for reducing febrile upper respiratory illness, days of missed work, and days of antibiotic use was demonstrated in a large field trial. In young children, protective efficacy against culture confirmed influenza was demonstrated in a field trial with overall protective efficacy of 92% during a two year study. Vaccine was also highly protective against a strain not contained in the vaccine, with 86% protective efficacy demonstrated against this significantly drifted virus. Effectiveness measures, including protection against febrile otitis media and visits to the doctor were demonstrated. Live attenuated vaccine provides a significant new tool to help prevent influenza.

Influence of clinical case definitions with differing levels of sensitivity and specificity on estimates of the relative and absolute health benefits of influenza vaccination among healthy working adults and implications for economic analyses

Clinical illness case definitions for influenza and methods used to define influenza seasons can vary substantially from study to study. These differences often result in differing levels of sensitivity, specificity and positive predictive value for the case definitions used. We explored the implications of different case definitions and outcome periods on estimates of influenza vaccine effectiveness and cost benefit by conducting additional analyses of data collected from a randomized, double blind, placebo controlled trial of the trivalent, intranasal, live attenuated influenza virus vaccine in healthy working adults. Febrile upper respiratory tract illnesses occurring during the peak influenza period was identified as the most specific clinical case definition expected to have the highest positive predictive value for true influenza whereas events occurring on a day with any symptom occurring during the entire outcome period was identified as the most sensitive clinical case definition with the lowest positive predictive value for influenza. As expected, the former provided the highest estimates of vaccine effectiveness (28.4% reduction in work loss days, 24.6% reduction in days with impaired productivity and 40.9% reduction in days with health care provider visits) but the lowest estimates of absolute reductions in events (42.4 work loss days prevented per 1000, 79.0 impaired productivity days per 1000, and 16.5 days with health care provider visits per 1000). On the other hand, events on days with any symptom during the entire outcome period provided the lowest estimates of vaccine effectiveness (18% reduction in work loss days, 18% reduction in days with impaired productivity, and 13% reduction in days with health care provider visits) but the highest estimates of absolute reductions in events (186.4 work loss days per 1000, 271.5 impaired productivity days per 1000, and 44.8 days with health care provider visits per 1000). When applied to a cost benefit analysis, the more specific case definition provided a break even cost for vaccination of US$ 6.58 whereas the more sensitive case definition provided a break even cost for vaccination of US$ 43.07. Clearly the latter combination is most appropriate when trying to assess the total population level impact of a vaccine preventable disease and the potential cost effectiveness of vaccination whereas the former may be most appropriate for assessing whether the vaccine actually works. The definitions of clinical influenza illness and outcome periods should be selected to match the study question.

Rhinopharyngites de l’enfant

La rhinopharyngite désigne une inflammation modérée des voies aériennes supérieures d’origine infectieuse. Les signes habituels en sont l’obstruction nasale, la rhinorrhée, l’éternuement, la douleur pharyngée et la toux. Le terme de rhinopharyngite est spécifiquement français. Les auteurs anglo-saxons parlent de rhume (common cold) ou de upper respiratory tract infection (URI) pour décrire une inflammation aiguë des voies aériennes supérieures, et d’adénoïdite chronique (chronic adenoiditis) pour désigner une infection chronique des végétations adénoïdes responsable de rhinorrhées fébriles itératives ou d’obstruction des voies aériennes supérieures. Les rhinopharyngites aiguës non compliquées sont d’origine virale. Leur évolution spontanée est habituellement rapide et non compliquée. Elles ne nécessitent donc ni prélèvement bactériologique ni antibiothérapie systématique. En première intention, elles relèvent exclusivement d’un traitement antalgique et antipyrétique associé à des lavages des fosses nasales au sérum salé iso- ou hypertonique. Les complications des rhinopharyngites sont infectieuses, essentiellement représentées par les otites et les sinusites, et respiratoires obstructives. Le caractère fréquemment itératif des rhinopharyngites à partir de l’âge de 6 mois reflète un processus physiologique de maturation du système immunitaire. En présence de rhinopharyngites fréquentes et invalidantes, les principaux facteurs de risque devant être recherchés et si possible éradiqués sont le tabagisme passif et la fréquentation d’une collectivité d’enfants. L’adénoïdectomie n’est pas indiquée en l’absence de complications. Le développement d’antiviraux efficaces dans la prévention et dans le traitement des rhinopharyngites fait l’objet d’intenses recherches cliniques et expérimentales.

Drug approval highlights for 2003

In the past 12 months, the FDA has approved important new pharmaceutical drugs and devices of particular interest to primary health care providers. The drugs include: Oxytrol (for urinary incontinence), Valtrex (for reducing the risk of heterosexual transmission of genital herpes), Femring (for vaginal delivery of hormone therapy), Uroxatral (for benign prostatic hypertrophy), Levitra (for erectile dysfunction), Flumist (for preventing influenza), Xolair (for asthma), Raptiva (for psoriasis), Cubicin (for skin infections), Crestor (for hypercholesterolemia), and Coreg (for severe heart failure).

Influenza virus vaccine live intranasal--MedImmune vaccines: CAIV-T, influenza vaccine live intranasal

MedImmune Vaccines (formerly Aviron) has developed a cold-adapted live influenza virus vaccine [FluMist] that can be administered by nasal spray. FluMist is the first live virus influenza vaccine and also the first nasally administered vaccine to be marketed in the US. The vaccine will be formulated to contain live attenuated (att) influenza virus reassortants of the strains recommended by the US Public Health Service for each 'flu season. The vaccine is termed cold-adapted (ca) because the virus has been adapted to replicate efficiently at 25 degrees C in the nasal passages, which are below normal body temperature. The strains used in the seasonal vaccine will also be made temperature sensitive (ts) so that their replication is restricted at 37 degrees C (Type B strains) and 39 degrees C (Type A strains). The combined effect of the antigenic properties and the att, ca and ts phenotypes of the influenza strains contained in the vaccine enables the viruses to replicate in the nasopharynx to produce protective immunity. The original formulation of FluMist requires freezer storage throughout distribution. Because many international markets do not have distribution channels well suited to the sale of frozen vaccines, Wyeth and MedImmune are collaborating to develop a second generation, refrigerator-stable, liquid trivalent cold-adapted influenza vaccine (CAIV-T), which is in phase III trials. Initially, the frozen formulation will only be available in the US. For the 2003-2004 season, FluMist will contain A/New Caledonia/20/99 (H1N1), A/Panama/2007/99 (H3N2) (A/Moscow/10/99-like) and B/Hong Kong/330/2001. Aviron was acquired by MedImmune on 15 January 2002. Aviron is now a wholly-owned subsidiary of MedImmune and is called MedImmune Vaccines. Aviron acquired FluMist in March 1995 through a Co-operative Research and Development Agreement (CRADA) with the US NIAID, and a licensing agreement with the University of Michigan, Ann Arbor, USA. In June 2000, the CRADA was extended through to June 2003. Aviron holds exclusive worldwide rights to the vaccine except for Japan, where Kaketsuken Pharmaceuticals (also known as Chemo-Sero-Therapeutic Research Institute) is the licensee. Aviron signed a development and licensing agreement with Sang-A in Korea, which was to manufacture and market FluMist in South Korea. However, in 2000, Aviron terminated all rights and licences to Sang-A relating to FluMist. Sang-A responded by filing a suit against Aviron in August 2000, for breach of contract and unfair and deceptive business practices. Aviron filed a counter claim denying the allegations in late Sept 2001. In 1999, Aviron entered into an agreement with Wyeth-Lederle Vaccines for worldwide collaboration in the marketing of FluMist. Under the $US400 million agreement, Aviron granted Wyeth-Lederle Vaccines exclusive worldwide rights to market FluMist. Wyeth-Lederle Vaccines and Aviron (now Med-Immune Vaccines) will co-promote FluMist in the US, while Wyeth-Lederle Vaccines will have the exclusive right to market the product ex-US. Wyeth will hold marketing rights for up to 11 years. The collaboration excludes Korea, Australia, New Zealand and certain South Pacific countries. The companies will collaborate on the regulatory, clinical and marketing programmes for FluMist and both will manufacture liquid FluMist. MedImmune Vaccines is to receive an average of 40% of revenues from FluMist; the percentage will be higher in the US and lower in other markets. Aviron received a $US15 million upfront payment upon initiation of the agreement. In December 2000, Aviron received a $US15.5 million milestone payment from American Home Products (now Wyeth) after the US FDA accepted the BLA for FluMist. MedImmune Vaccines will receive a $US20 million milestone payment upon US FDA approval. Aviron also received an additional $US20 million in milestone payments for expaory body recommendations. MedImmune Vaccines is entitled to receive a $US10 million payment for submitting a licence application in Europe, a $US27.5 million payment for approval of a refrigerator-stable liquid formulation of FluMist and as much as $US50 million for licensing of FluMist internationally. In July 2003 MedImmune announced that it had received approximately $US28 million in milestone payments during Q2 of 2003 for the approval of FluMist. CSL Ltd of Australia will collaborate on the development, sale and distribution of MedImmune Vaccine's vaccine in Australia, New Zealand and certain countries in the South Pacific. MedImmune is to acquire vaccine research programmes in respiratory syncytial virus and cytomegalovirus from MedImmune Vaccines. The company's primary interest is in FluMist. In May 2002, MedImmune licensed exclusive rights to Crucell's proprietary human cell line PER.C6 for use in its influenza vaccine programmes. On 11 March 2002, American Home Products changed its name and the names of its subsidiaries Wyeth-Ayerst and Wyeth-Lederle to Wyeth. Wyeth's vaccines division is called Wyeth Vaccines. On 29 September 2000, Aviron announced that it had been awarded a $US2.7 million Challenge Grant from NIAID for development of vaccines against pandemic strains of influenza based on FluMist intranasal technology. The cold-adapted live influenza vaccine has been widely evaluated in the US and Japan since 1975 in clinical trials involving several thousand people. Aviron completed phase II clinical trials in adults in the US and phase III trials in US children aged 15-71 months. Additional phase III trials in adults and the elderly are ongoing. Aviron also commenced phase III trials to test the safety of its intranasal live vaccine in children with moderate to severe asthma. The vaccine is delivered using the AccuSpray nasal delivery system by Becton Dickinson, which will supply the system for FluMist through the 2001-2002 influenza season under an agreement with Aviron made in August 1998. On 7 March 2000, Aviron announced that Wyeth-Lederle Vaccines (now Wyeth Vaccines) had begun a phase II bridging study with a refrigerator-stable liquid formulation of FluMist in the Southern Hemisphere. The randomised single-blind trial is being conducted together with Aviron (now MedImmune Vaccines) and is intended to demonstrate clinical equivalence between frozen and liquid FluMist. At the time of the announcement, more than 500 children aged 1-3 years had been enrolled to receive either frozen or liquid FluMist. The final study population is approximately 1300. If clinical equivalence of the two forms of FluMist is demonstrated in this study, MedImmune Vaccines will be able to use data from trials of frozen FluMist in licence applications for international markets. Aviron submitted a Biologics Licence Application (BLA) to the US FDA in July 1998. The FDA rejected this application on the grounds of a lack of data on manufacturing, validation and stability. In June 1999, Aviron announced that it had completed a bridging study on FluMist designed to provide some of the manufacturing data required by the US FDA on FluMist prepared at one of two manufacturing sites. Preliminary analysis indicated that the results had met the company's objectives. The primary endpoint of the study was to demonstrate that the batch of FluMist blended and filled at Packaging Coordinators, Inc. in Philadelphia had similar immunogenicity for all three 1997-98 influenza strains as the vaccine used in earlier clinical trials, which was manufactured by Medeva Pharma (now Evans Vaccines, a subsidiary of PowderJect Pharmaceuticals) in England. The secondary endpoint was to show that these lots of FluMist had similar safety and tolerability profiles. Aviron then submitted a BLA in October 2000. However, in late July 2001, an FDA advisory committee declined to recommend approval of the vaccine, citing concerns with safety. Aviron subsequently received a Complete Response Letter from the FDA requesting additional clinical and manufacturing data. Aviron stated that it should be able to provide these data without conducting further clinical trials. In January 2002, Aviron submitted additional clinical and manufacturing data on FluMist to the US FDA. MedImmune received a second Complete Response Letter from the US FDA on 10 July 2002, requesting clarification and additional data relating to previously submitted information. One of the most significant issues raised by the US FDA was the exacerbated rate of asthma and wheezing in 18-35-month-old patients using FluMist. MedImmune is considering two options to address this issue; to either exclude patients with asthma and wheezing from the label, or to exclude 18- to 30-month-old patients from the proposed indication. On 26 August 2002, MedImmune reported that it had completed the submission of information requested by the US FDA for FluMist. On 17 December 2002, the US FDA's Vaccination and Related Biologicals Products Advisory Committee (VRBPAC) recommended that the FDA approve FluMist to prevent influenza in healthy children, adolescents and adults (ages 5-49 years). Even though the VRBPAC voted in favour of the product's safety in the 50- to 64-year age group, they believed that the data set on efficacy for this age group was insufficient. The committee has also recommended that head-to-head studies should be conducted comparing FluMist to the marketed trivalent inactivated vaccine. Additional clinical trials suggested by the VRBPAC were shedding studies to more clearly define the probability of transmitting the influenza vaccine virus to a high-risk patient and annual revaccination studies. On 30 January 2003, MedImmune announced that it had received a Complete Response Letter from the US FDA requesting clarification and additional information relating to data previously submitted. No additional clinical trials were requested. The company responded to the five questions contained in the letter on 7 February 2003. (ABSTRACT TRUNCATED)

Cell-based assay for the determination of temperature sensitive and cold adapted phenotypes of influenza viruses

The determination of temperature sensitive (ts) and cold adapted (ca) phenotype for influenza A and B strains has been conducted traditionally using embryonated chicken eggs. As attempts are made to move away from the use of eggs in the manufacturing process of influenza vaccines, it will become useful to develop cell-based assays to support cell culture-based vaccine production. In this study, MDCK cells have been evaluated as a tool for determining the ts and ca phenotypes associated with live attenuated influenza viruses. Direct comparisons were made of these phenotypes carried out in eggs. Reassortants made from the Russian live attenuated influenza donor strains A/Leningrad/134/17/57 (H2N2) and B/USSR/60/69 were prepared entirely in MDCK cells and their phenotypes evaluated using the MDCK cell-based assay. It is concluded that MDCK cells are more sensitive than eggs for the measurement of ts and ca phenotype of influenza viruses (particularly for influenza A) and they provide an alternative means for screening candidate reassortants prior to determining their genome composition.

Safety and efficacy of trivalent inactivated influenza vaccine in young children: a summary for the new era of routine vaccination

Increasing use of influenza vaccine in children is expected as this important virus becomes more widely recognized as a major cause of morbidity in young children. Clinicians and third party payers must consider the implications of national vaccine use recommendations, with their current focus on young children, on their practices and on the community at large. Two influenza vaccines are available in the United States, an inactivated, trivalent intramuscular formulation (TIV) which is approved for use among children > or =6 months of age; and a live, attenuated intranasal trivalent preparation (LAIV) indicated for healthy persons 5 to 49 years of age. This review summarizes available data regarding the safety and efficacy of TIV, in comparison with LAIV, with particular attention to children <9 years of age, the population for whom two doses of vaccine are recommended for first time vaccination. It is apparent that relatively few data are available on the safety of TIV in young children, that important age-specific differences in TIV vaccine efficacy exist and that LAIV appears similar to TIV with regard to safety and efficacy in younger children, but no head-to-head comparison of these two licensed products is available.

Safety and efficacy of live attenuated, cold-adapted, influenza vaccine-trivalent

This article describes the efficacy, immunogenicity, and safety of CAIV-T. This vaccine has the potential to significantly contribute to the control of influenza infection and influenza-associated illnesses, including febrile otitis media and lower respiratory disease. When compared with inactivated vaccine, CAIV-T has significant advantages in convenience of administration. The high efficacy of CAIV-T and its efficacy in children against a significantly drifted strain of H3N2 (A/Sydney), a strain not contained in the vaccine, are compelling observations for use of the vaccine in children. Effectiveness in adults was demonstrated using the same vaccine strain against the drifted H3N2 strain. The proposed vaccine administration schedule for healthy individuals aged 9 to 49 years is a single dose administered annually before the winter. For children aged 5 to 8 years, two doses are recommended the first year they are immunized with CAIV-T to ensure protection against all strains contained in the vaccine. Thereafter, a single annual revaccination is sufficient.

Influenza virus: immunity and vaccination strategies. Comparison of the immune response to inactivated and live, attenuated influenza vaccines

Influenza virus is a globally important respiratory pathogen which causes a high degree of morbidity and mortality annually. The virus is continuously undergoing antigenic change and thus bypasses the host's acquired immunity to influenza. Despite the improvement in antiviral therapy during the last decade, vaccination is still the most effective method of prophylaxis. Vaccination induces a good degree of protection (60-90% efficacy) and is well tolerated by the recipient. For those at risk of complications from influenza, annual vaccination is recommended due to the antigenic changes in circulating strains. However, there is still room for improvement in vaccine efficacy, long-lasting effect, ease of administration and compliance rates. The mucosal tissues of the respiratory tract are the main portal entry of influenza, and the mucosal immune system provides the first line of defence against infection. Secretory immunoglobulin A (SIgA) and IgM are the major neutralizing antibodies directed against mucosal pathogens. These antibodies work to prevent pathogen entry and can function intracellularly to inhibit replication of virus. This review describes influenza virus infection, epidemiology, clinical presentation and immune system response, particularly as it pertains to mucosal immunity and vaccine use. Specifically, this review provides an update of the current status on influenza vaccination and concentrates on the two main types of influenza vaccines currently in use, namely the cold-adapted vaccine (CAV) given intranasally/orally, and the inactivated vaccine (IV) delivered subcutanously or intramuscularly. The commercially available trivalent IV (TIV) elicits good serum antibody responses but induces poorly mucosal IgA antibody and cell-mediated immunity. In contrast, the CAV may elicit a long-lasting, broader immune (humoral and cellular) response, which more closely resembles natural immunity. The immune response induced by these two vaccines will be compared in this review.

Intranasal flu vaccine available this season

FluMist provides a convenient alternative to the traditional flu shot. Use of a live attenuated virus that stimulates an immune response directly in the nasal passages has certain therapeutic advantages in some patients. However, the cost of this form of flu vaccine is likely to be borne entirely by the patient.

Occurrence of respiratory virus: time, place and person

BACKGROUND

Respiratory viruses account for most respiratory infections. Although analysis of epidemiologic information regarding viral seasonality, sites of transmission and susceptible populations is essential to devising strategies for limiting epidemics, few long term epidemiologic studies have addressed these questions.

METHODS

Epidemiologic findings identifying susceptible populations, as well as temporal and geographic patterns of infection with influenza virus, respiratory syncytial virus, rhinovirus and parainfluenza virus were reviewed.

CONCLUSIONS

Influenza is the virus most frequently associated with outbreaks of respiratory infection resulting in medical consultation as well as virus-related lethality. Similar symptom profiles and overlapping seasonality of respiratory syncytial virus and other viruses may sometimes complicate surveillance and treatment. Although vaccination and antiviral drugs are virus-specific, factors that promote transmission and thus strategies for limiting outbreaks are similar for various respiratory viruses.

Rinofaringitis infantiles

La rinofaringitis designa una inflamación moderada de las vías respiratorias superiores de origen infeccioso. Sus signos habituales son obstrucción nasal, rinorrea, estornudos, dolor faríngeo y tos. Los autores anglosajones hablan de catarro (common cold) o de infección de vías respiratorias altas para describir una inflamación de las vías respiratorias superiores, y de adenoiditis crónica (chronic adenoiditis) para designar una infección crónica de las vegetaciones adenoides que produce rinorrea febril recidivante u obstrucción de las vías respiratorias altas. Las rinofaringitis agudas no complicadas son de origen vírico. Habitualmente su evolución espontánea es rápida y sin complicaciones. Por tanto, no hay que obtener muestras bacteriológicas ni hacer un tratamiento antibiótico sistemático. Como tratamiento de primera línea, sólo precisan analgésicos y antipiréticos asociados a lavados de las fosas nasales con suero salino isotónico o hipertónico. Las complicaciones de las rinofaringitis son infecciosas –representadas esencialmente por las otitis y las sinusitis– y respiratorias obstructivas. El carácter a menudo repetitivo de las rinofaringitis a partir de los 6 meses de edad refleja un proceso fisiológico de maduración del sistema inmunitario. Cuando existen rinofaringitis frecuentes e invalidantes, los principales factores de riesgo que se deben buscar, y de ser posible erradicar, son el tabaquismo pasivo y los contactos con una población infantil. La adenoidectomía ya no está indicada si no existen complicaciones. Se están realizando investigaciones clínicas y experimentales sobre el desarrollo de fármacos antivíricos eficaces para la prevención y el tratamiento de las rinofaringitis.

Every nose counts: a new influenza vaccine for all healthy schoolchildren?

Influenza is a vaccine-preventable disease. However, influenza virus spreads among children in schools and daycare centers, then to families and communities, causing uncontrolled epidemics every winter. The United States Food and Drug Administration evaluated and approved an investigational live-attenuated, cold-adapted, trivalent influenza vaccine for licensure, for prevention of influenza in healthy children and healthy adults, 5 through 49 years of age. Could protection of healthy schoolchildren against influenza limit its spread and benefit society?

Vaccines for preventing influenza in healthy adults

BACKGROUND

Three different types of influenza vaccines are currently produced worldwide. None is traditionally targeted to healthy adults. Despite the publication of a large number of clinical trials, there is still substantial uncertainty about the clinical effectiveness of influenza vaccines and this has negative impact on the vaccines acceptance and uptake.

OBJECTIVES

To assess the effects of vaccines on influenza in healthy adults. To assess the effectiveness of vaccines in preventing cases of influenza in healthy adults. To estimate the frequency of adverse effects associated with influenza vaccination in healthy adults.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 2004) which contains the Cochrane Acute Respiratory Infections Group trials register; MEDLINE (January 1966 to December 2003); and EMBASE (1990 to December 2003). We wrote to vaccine manufacturers and first or corresponding authors of studies in the review.

SELECTION CRITERIA

Any randomised or quasi-randomised studies comparing influenza vaccines in humans with placebo, control vaccines or no intervention, or comparing types, doses or schedules of influenza vaccine. Live, attenuated or killed vaccines or fractions thereof administered by any route, irrespective of antigenic configuration were considered. Only studies assessing protection from exposure to naturally occurring influenza in healthy individuals aged 14 to 60 (irrespective of influenza immune status) were considered.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Twenty five reports of studies involving 59,566 people were included. The recommended live aerosol vaccines reduced the number of cases of serologically confirmed influenza by 48% (95% confidence interval (CI) 24% to 64%), whilst recommended inactivated parenteral vaccines had a vaccine efficacy of 70% (95% CI 56% to 80%). The yearly recommended vaccines had low effectiveness against clinical influenza cases: 15%(95% CI 8% to 21%) and 25% (95% CI 13% to 35%) respectively. Overall the percentage of participants experiencing clinical influenza decreased by 6%. Use of the vaccine significantly reduced time off work but only by 0.16 days for each influenza episode (95% CI 0.04 to 0.29 days); Analysis of vaccines matching the circulating strain gave higher estimates of efficacy, whilst inclusion of all other vaccines reduced the efficacy.

REVIEWERS' CONCLUSIONS

Influenza vaccines are effective in reducing serologically confirmed cases of influenza. However, they are not as effective in reducing cases of clinical influenza and number of working days lost. Universal immunisation of healthy adults is not supported by the results of this review.

Intranasal Cold-Adapted Influenza Virus Vaccine Combined with Inactivated Influenza Virus Vaccines

Although influenza vaccine delivery strategies have improved coverage rates to unprecedented levels nationally among persons aged 65 years and older, influenza remains one of the greatest vaccine-preventable threats to public health among elderly in the US. A new, intranasal live attenuated influenza vaccine (LAIV) was recently approved by the US FDA for use in persons aged 5-49 years, which excludes the elderly population. Limitations of immune response to inactivated influenza vaccine (IAIV) and effectiveness of current influenza vaccination strategies among the elderly suggest that a combined approach using LAIV and/or the IAIV in various permutations might benefit this group. We explore characteristics of the LAIV, data regarding its utility in protecting against influenza in the elderly, and challenges and opportunities regarding potential combined inactivated/live attenuated vaccination strategies for the elderly. Although LAIV appears to hold promise either alone or in combination with IAIV, large well conducted randomised trials are necessary to define further the role of LAIV in preventing influenza morbidity and mortality among the elderly. We also suggest that innovative vaccine coverage strategies designed to optimise prevention and control of influenza and minimise viral transmission in the community must accompany, in parallel, the acquisition of clinical trials data to best combat morbidity and mortality from influenza.

The influence of health professionals on the uptake of the influenza immunization

Influenced by the Department of Health's aim to increase the uptake of the influenza immunization to 70% among those eligible, this study aimed to compare three methods of promoting influenza immunization among over 65 year old patients in a GP practice, and to identify if a particular promotion method was more effective among either of two defined age groups. The sample (n = 90) was randomly allocated into three intervention groups, and then subdivided into two age groups. A different subject experimental design was used to compare the groups. Statistical analysis of the data showed no significant difference in influenza immunization uptake between the three intervention groups, or the age-defined sub-groups. However, although not significant at 5% significance level, participants aged 72 years and over showed a greater uptake among those visited by a health professional. The findings suggest that a larger study using the same interventions would produce significant results.

Pharmaceuticals and worker productivity loss: a critical review of the literature

Many chronic illnesses that affect the working population can cause losses in productivity. The extent to which these productivity losses can be reduced by pharmacological treatment is of particular interest to employers, who bear the productivity costs and subsidize the cost of employees' health care. In the past several years, the effects of pharmaceuticals on productivity losses have been tested in numerous studies, including randomized, double-blind, placebo-controlled trials. In this article, we summarize and critically review these studies and, where appropriate, provide quantitative overviews. The evidence is very good for about a dozen drug classes that pharmaceuticals reduce productivity losses caused by respiratory illnesses (ie, asthma, allergic disorders, bronchitis, upper respiratory infections, and influenza) diabetes, depression, dysmenorrhea, and migraine. We also discuss the calculation of productivity costs, reductions in which may partially or completely offset the costs of treatment. This information should be helpful to occupational physicians who are increasingly providing recommendations on employer benefit plan designs and pharmaceutical benefits.

Local and systemic immune response in nursing-home elderly following intranasal or intramuscular immunization with inactivated influenza vaccine

Intramuscular (IM) influenza vaccines are only 30-40% effective in preventing clinical illness among the elderly, and their effectiveness in eliciting mucosal response may be even lower. The aim of the present study was to evaluate the immunological effect of a novel inactivated intranasal (IN) trivalent whole influenza virus vaccine among nursing-home elderly. Twenty-one institutionalized elderly subjects were vaccinated IN with an inactivated novel vaccine, twice, 21 days apart, and with no adverse effects. Twenty-two subjects were vaccinated once with a commercial IM vaccine. Viral strains used in the 1998/9 vaccine (20 microg of each per dose) were A/Beijing/262/95, A/Sydney/5/97 and B/Harbin/7/94. Serum antibodies (IgG and IgM) and nasal IgA were determined by the hemagglutination inhibition (HI) test and enzyme-linked immunosorbent assay (ELISA), respectively. Mucosal antibody response to the three vaccine strains was detected in 47.6-71.4% and 18.1-31.8% of IN and IM immunized subjects, respectively. Serum antibody response to the three antigens tested was detected in 20.0-61.9% and 18.2-72.7% of IN and IM immunized subjects, respectively. Seroconversion was not significantly different after IN or IM vaccination for both A/Sydney and B/Harbin, but higher for A/Beijing following IM vaccination. On study completion, 57.1, 65.0 and 50.0% of IN vaccinees were seroprotected to A/Beijing, A/Sydney and B/Harbin, respectively. Similarly, 68.1, 77.2 and 54.5% were immune after IM vaccination. The IN vaccine tested was significantly more effective than the IM vaccine in inducing mucosal IgA response. This may prevent influenza at its early stages and thus contribute to the reduction of morbidity and complications in nursing-home elderly.

[Influenza]

Influenza (flu) is an acute contagious viral infection characterized by inflammation of the respiratory tract that every winter affects more than 100 million people in Europe, Japan and the United States of America, also being responsible for several thousand of excess deaths (data from the United States reveal between 20,000 to 40,000 excess deaths annually). The Mixovirus influenzae is the agent that causes influenza, commonly called flu. There are 3 types of influenza virus: A, B, C, and only types A and B are perceived to be clinically relevant in humans. Due to the segmented nature of its genetic material, the influenza virus is highly mutagenic, causing frequent insertion of new antigenic strains into the community, against which the population presents no immunity. Presently, there are few options for the control of influenza and annual immunization is the most effective means to prevent disease and its complications. In Brazil, according to data collected by the VigiGripe's Project - linked to the Federal University of Sao Paulo -, circulation of the influenza virus also has a seasonal pattern, with peak activity occurring between May and September. Yearly vaccination is, therefore, best indicated on March and April. Currently, there are four medications available for the treatment of influenza viruses: amantadine and rimantadine, and two second generation pharmaceutical products, the neuraminidase inhibitors, oseltamivir and zanamivir. The latter two drugs have set the stage for a new approach to the management and control of influenza infections.

Multiple amino acid residues confer temperature sensitivity to human influenza virus vaccine strains (FluMist) derived from cold-adapted A/Ann Arbor/6/60

FluMist influenza A vaccine strains contain the PB1, PB2, PA, NP, M, and NS gene segments of ca A/AA/6/60, the master donor virus-A strain. These gene segments impart the characteristic cold-adapted (ca), attenuated (att), and temperature-sensitive (ts) phenotypes to the vaccine strains. A plasmid-based reverse genetics system was used to create a series of recombinant hybrids between the isogenic non-ts wt A/Ann Arbor/6/60 and MDV-A strains to characterize the genetic basis of the ts phenotype, a critical, genetically stable, biological trait that contributes to the attenuation and safety of FluMist vaccines. PB1, PB2, and NP derived from MDV-A each expressed determinants of temperature sensitivity and the combination of all three gene segments was synergistic, resulting in expression of the characteristic MDV-A ts phenotype. Site-directed mutagenesis analysis mapped the MDV-A ts phenotype to the following four major loci: PB1(1195) (K391E), PB1(1766) (E581G), PB2(821) (N265S), and NP(146) (D34G). In addition, PB1(2005) (A661T) also contributed to the ts phenotype. The identification of multiple genetic loci that control the MDV-A ts phenotype provides a molecular basis for the observed genetic stability of FluMist vaccines.

The common cold

Despite great advances in medicine, the common cold continues to be a great burden on society in terms of human suffering and economic losses. Of the several viruses that cause the disease, the role of rhinoviruses is most prominent. About a quarter of all colds are still without proven cause, and the recent discovery of human metapneumovirus suggests that other viruses could remain undiscovered. Research into the inflammatory mechanisms of the common cold has elucidated the complexity of the virus-host relation. Increasing evidence is also available for the central role of viruses in predisposing to complications. New antivirals for the treatment of colds are being developed, but optimum use of these agents would require rapid detection of the specific virus causing the infection. Although vaccines against many respiratory viruses could also become available, the ultimate prevention of the common cold seems to remain a distant aim.

Bedside rapid flu test and zanamivir prescription in healthy working adults: a cost-benefit analysis

BACKGROUND

Zanamivir, a neuraminidase inhibitor, reduces the number of days of illness in influenza-positive patients. New bedside rapid flu tests (RFT) should increase the number of influenza-positive patients whom receive zanamivir appropriately.

OBJECTIVE

To estimate the economic effects of implementing RFT and zanamivir among unvaccinated healthy working adults who consult within 2 days of the onset of influenza-like symptoms.

METHODS

We constructed a decision tree to perform a cost-benefit analysis from a societal perspective. Clinical outcome, i.e. number of influenza days averted, and societal costs were compared for three strategies: RFT and conditional zanamivir prescription;systematic zanamivir prescription; and no zanamivir. A two-way sensitivity analysis was performed including the proportion of influenza-positive patients.

RESULTS

During influenza epidemics, systematic zanamivir prescription provided the best health outcome (0.81 influenza days averted) and minimised societal costs (reduced by 29.80 US dollars per person compared with no zanamivir; 1999 values). RFT with conditional zanamivir averted 0.65 influenza days and saved 14.40 US dollars per person. When the proportion of influenza-positive patients was under 39%, the no zanamivir strategy yielded the greatest societal savings; otherwise, systematic zanamivir was the dominant strategy. Medical costs associated with no zanamivir were 88.70 US dollars per patient consulting with influenza-like illness, and increased to 125.50 US dollars with systematic zanamivir and to 127.60 US dollars with RFT and conditional zanamivir.

CONCLUSIONS

Due to poor sensitivity of current RFT, systematic zanamivir prescription without RFT for unvaccinated healthy working adults should be recommended during influenza epidemics.

The pathogenesis and management of influenza virus infection in organ transplant recipients

Infection with influenza viruses poses specific problems in adult and pediatric organ transplant recipients, including a higher rate of pulmonary and extra-pulmonary complications. Also, data suggest that influenza is associated with acute cellular rejection and chronic allograft dysfunction. The main strategy of influenza prevention has been influenza immunization in order to stimulate local and systemic antibodies. However, studies have shown that antibody response to inactivated influenza vaccine is decreased in all groups of organ transplant recipients. A live attenuated influenza virus vaccine is nearing approval in the United States. However, studies are needed in organ transplant recipients to determine whether the live attenuated influenza virus vaccine can enable these patients to mount a protective immune response and what degree of protection or amelioration of illness is provided by such vaccine. It is also important to verify the safety of this vaccine in organ transplant recipients because live virus may cause severe disease in these patients. Therefore, other modalities of prevention against influenza, such as chemoprophylaxis with antiviral drugs, should be considered in this patient population. The current review provides an overview of the incidence, clinical manifestations, and strategies for the prevention and management of influenza in organ transplant recipients.

Influenza pandemic preparedness action plan for the United States: 2002 update

Preparation for the next influenza pandemic includes development of a national plan that has 3 goals: to limit the burden of disease, to minimize social disruption, and to reduce economic losses attributable to the pandemic. Priority areas to be addressed and improved in the plan to achieve these goals include global and national influenza surveillance, vaccine development and production, vaccine use and coverage, chemoprophylaxis and therapy, guidelines for clinical care and health resources management, emergency preparedness, and research. This multifaceted plan will require close collaboration between public and private sectors to ameliorate the potentially devastating impact of pandemic influenza.

Universal vaccination of healthy children against influenza: a role for the cold-adapted intranasal influenza vaccine

The incidence of influenza in children well exceeds that of the elderly and has been identified as the basis for 20% of doctor visits for children during the winter. The disease results in over 100 hospitalizations per 100000 person-months in children <2 years of age. Furthermore, children serve as the major vector in the community; thus, influenza in children results in significant costs to society. Although efficacious, the current intramuscular, inactivated influenza vaccine is infrequently used in children, and is currently targeted only at children at high risk and those who are household members of such individuals. Experts believe that vaccinating only high risk individuals has little impact on the cycle of annual epidemics, but that universal vaccination of children may very well have a substantial impact. Experimental data support this. A recently published cost-benefit analysis indicated that routine, school-aged vaccination through individual visits to a clinician would save 4 US dollars per child vaccinated. A group program such as a school-based one would save 35 US dollars. One obstacle to universal vaccination includes the real and perceived resistance to the addition of yet another annual injection to the already crowded schedule of routine childhood immunizations. Nearing licensure is an intranasal, live attenuated, cold-adapted intranasal influenza vaccine. Cold-adaptation prevents replication in the lower respiratory tract. Trials have demonstrated immunogenicity, safety, and tolerability in adults as well as children. Placebo-controlled trials have shown efficacy rates of 83 to 94%. This novel vaccine addresses obstacles to universal childhood immunization and would permit a program of routine use that would dramatically reduce transmission and stem epidemics of influenza.

Evaluation of adverse effects of vaccines: the case-control approach

When the hypothesis of a link between vaccination and a possible adverse outcome arises, further investigation is required to confirm or refute the suspicion. Given the rarity of most serious adverse effects, a case-control approach will often be chosen. This paper discusses aspects of the design, analysis and interpretation of case-control studies to evaluate vaccine adverse effects. Potential biases (and how to minimise such biases) in the selection of cases and assessment of vaccine exposure and the potential for confounding are discussed. Finally the increasing use of electronic databases in the evaluation of vaccine adverse effects is considered.

The role of live influenza vaccines in children

Live attenuated cold-adapted influenza vaccines (CAIVs) have been developed over the past two decades by taking advantage of the segmented RNA genome of influenza and creating attenuated reassortants containing contemporary hemagglutinin (HA) and neuraminidase (NA) genes. These vaccines have been shown to be easily administered, safe and immunogenic in adults and children. Recent trials of a trivalent live attenuated CAIV (CAIV-T, tradename FluMist, Aviron, Mt. View, CA) in children have demonstrated greater than 85% efficacy against culture positive H3N2 and B influenza illness and complications, such as otitis media. CAIV-T also prevented shedding of H1N1 virus in 83% of vaccinated subjects after a monovalent CAIV challenge. Nasal IgA and serum HA inhibition (HAI) antibody produced by these vaccines have been associated with protection against infection, but protection may exist even in the absence of identifiable antibody response. Work to date documenting phenotypic and genetic stability, low likelihood of reactogenicity, infrequent transmissibility and attenuating properties of reassortants heralds promise for the broad use of this vaccine. Targeting children to receive this vaccine may now prove practical and may serve to reduce overall influenza morbidity, given the significant contribution of the pediatric age group of children to influenza illness burden and community spread. Studies of vaccine use in community settings will aid in determining the public health future of this approach.

Safety of the trivalent, cold-adapted influenza vaccine (CAIV-T) in children

The trivalent, cold-adapted influenza vaccine (CAIV-T, FluMist, Aviron, Mountain View, CA) is a live attenuated influenza virus vaccine that is administered by nasal spray. CAIV-T is efficacious in preventing influenza virus infection. The vaccine was submitted to the Food and Drug Administration for licensure in healthy children and adults. Universal immunization is being considered in children, and an effective vaccine with minimal adverse reactions is thus required. The published studies on the safety of CAIV-T in children reviewed in this article were clinical trials sponsored by the National Institutes of Health (NIH) conducted in children from 1975 to 1991, clinical trials from 1991 to 1993 sponsored by a cooperative agreement between NIH and Wyeth-Ayerst Research, and clinical trials from 1995 to the present sponsored by a cooperative agreement between NIH and Aviron. Safety assessments included the occurrence of: 1) specific influenza-like symptoms, unexpected symptoms, and use of medications within the first 10 days after vaccination; 2) acute illness and use of medication within 11 to 42 days postvaccination; 3) serious adverse events and rare events within 42 days after vaccination; 4) healthcare utilization within 14 days after vaccination; and 5) acute respiratory symptoms with annual sequential vaccine doses. CAIV-T was safe and well-tolerated. Transient, mild respiratory symptoms were observed in a minority (10%-15%) of children and primarily with the first CAIV-T dose. Vomiting and abdominal pain occurred in fewer than 2 percent of CAIV-T recipients. The gastrointestinal symptoms were mild and of short duration. An excess of illness or use of medication was not observed after the 10th day of vaccination. Sequential annual doses of CAIV-T were well-tolerated and not associated with increased reactogenicity. CAIV-T did not cause an increase in healthcare utilization. Thus CAIV-T is safe in healthy children and should complement the use of inactivated influenza vaccine, trivalent (IIV-T) in children with underlying chronic conditions.

Safety and tolerability of cold-adapted influenza virus vaccine in children and adolescents with asthma

BACKGROUND

Influenza infections can cause severe respiratory disease in high risk persons such as those with asthma, but immunization rates for high risk groups remain suboptimal. An investigational influenza virus vaccine, trivalent, types A and B, live, cold-adapted (CAIV-T) administered by intranasal spray was shown previously to be effective in healthy adults and healthy children.

PURPOSE

To assess the safety and tolerability of CAIV-T in subjects 9 years of age and older with moderate to severe asthma.

METHODS

In this randomized, double blind, placebo-controlled study, spirometry was performed twice before vaccination to establish a baseline forced expiratory volume at 1 s (FEV1) and once 2 to 5 days thereafter. The primary outcome index was the percent change in percent predicted FEV1 before and after vaccination. Peak flows, clinical asthma symptom scores and nighttime awakening scores were measured daily from 7 days pre- to 28 days postvaccination.

RESULTS

The primary outcome index (percentage change in percent predicted FEV1) was not different between the two groups (0.2% vs. 0.4% for the treatment and placebo groups, respectively; P = 0.78). Secondary outcomes did not differ between the two groups; these included the number of subjects with a decrease in FEV1 > or =15% from baseline, reductions in peak flows > or =15%, > or =30% or > or =2 sd below baseline, use of beta-adrenergic rescue medications, asthma exacerbations and clinical asthma symptom scores before and after vaccination. The same proportion of subjects in each group experienced postvaccination symptoms within 10 days (92% and 91%, respectively; P = 1.0). No serious adverse event occurred.

CONCLUSION

CAIV-T was generally safe and well-tolerated in children and adolescents with moderate to severe asthma.

Safety, efficacy and effectiveness of cold-adapted, live, attenuated, trivalent, intranasal influenza vaccine in adults and children

Studies in children and adults revealed cold-adapted, live, attenuated, trivalent, intranasal influenza vaccine (CAIV-T) to be well accepted, well tolerated and highly protective against culture-confirmed influenza, and to provide significant health benefits. A 2 year, multicentre, double-blind, placebo-controlled efficacy field trial of CAIV-T in children aged 15-71 months with annual re-immunization revealed the vaccine to be highly protective against culture-confirmed influenza. Vaccine induced serum and secretory antibodies in vaccinated children. Overall, during 2 years of study, vaccine was 92% protective against culture-confirmed influenza. During the second year of study the vaccine was 86% protective against influenza A/Sydney/5/97-like virus, a significantly drifted strain not well matched to the vaccine. Antibody studies on children given CAIV-T revealed that high titres of cross-reacting antibodies to influenza A/Sydney/5/97 were induced with vaccination by live attenuated influenza A/Wuhan/359/95-like vaccine. Effectiveness measures revealed significant reductions in febrile illness (21% reduction in year 1, 19% reduction in year 2), febrile otitis media (33% reduction in year 1, 16% reduction in year 2) and associated antibiotic use among vaccinated children compared with placebo recipients. In adults, vaccination with CAIV-T resulted in protection during experimental challenge with virulent wild-type viruses. An effectiveness trial in adults demonstrated significant benefits of CAIV-T vaccine (28% reduction in days of missed work for febrile upper respiratory illness days with associated 45% reduction in days taking antibiotics). General use of CAIV-T has the potential to significantly reduce the impact of influenza in children and adults.

Cold-attenuated live influenza vaccines, a risk-benefit assessment

The principle of live attenuated influenza vaccines has been known for many decades. However, the pharmaceutical and clinical development according to current regulations, of modern live influenza vaccines based on cold adapted influenza viruses (CAIV) started only recently and these vaccines will most probably become an alternative within the next couple of years to licensed inactivated influenza vaccines that have been used routinely since the early 1940s. In contrast to contemporary trivalent inactivated influenza vaccines, which are administered intramuscularly, trivalent CAIV-based vaccines will be administered intranasally as a spray. Quality, safety and efficacy aspects related to CAIV vaccines as well as possible risks linked to the widespread use of these vaccines will be discussed in the following overview and compared to established influenza vaccines. Moreover, issues of practicality of CAIV vaccines focusing on the necessity of an annual update of influenza vaccines are addressed.

Safety, vaccine virus shedding and immunogenicity of trivalent, cold-adapted, live attenuated influenza vaccine administered to human immunodeficiency virus-infected and noninfected children

OBJECTIVE

To assess the safety of live, attenuated influenza vaccine (LAIV) administered to relatively asymptomatic or mildly symptomatic HIV-infected children and non-HIV-infected children.

METHODS

Twenty-five non-HIV and 24 HIV-infected children (CDC Class N or A1,2) were enrolled into this double blind, placebo-controlled study. Children were randomized within each HIV status group to one of two dosing regimens: Regimen 1, Dose 1 = LAIV, Dose 2 = placebo, Dose 3 = LAIV; or Regimen 2, Dose 1 = placebo, Dose 2 = LAIV, Dose 3 = LAIV. Study doses were separated by 28 to 35 days. Reactogenicity events within 10 days and adverse events within 28 to 35 days after each study dose were recorded. Blood HIV RNA concentrations, CD4 counts and CD4% were measured throughout the study on HIV-infected children. Quantitative influenza cultures were performed on nasal aspirates collected periodically from all children up to 28 to 35 days after each study dose. Influenza isolates were assessed for retention of the temperature-sensitive phenotype. Serum influenza HAI antibodies were measured before and after each LAIV vaccination.

RESULTS

No significant differences were found in rates of reactogenicity events and vaccine-related adverse events after placebo or the first dose of LAIV within each HIV status group, nor were differences found between HIV-infected and HIV-uninfected children after each dose of LAIV. Overall none of the HIV-infected children experienced a significant LAIV-related serious adverse event or influenza-like illness, making the one sided 95% CI of such a serious event occurring after LAIV 0 to 12%. No significant changes in geometric mean HIV RNA concentrations, CD4 counts or CD4% or prolonged or increased quantity of LAIV virus shedding occurred in HIV-infected children after receiving either dose of LAIV. All recovered influenza isolates retained the temperature-sensitive phenotype. After two doses of LAIV, 83% of the non-HIV-infected and 77% of the HIV-infected children had a > or = 4-fold rise in influenza antibody to at least one of the three LAIV strains.

CONCLUSION

If relatively healthy HIV-infected children become exposed to LAIV inadvertently, then serious adverse outcomes would not be expected to occur frequently.

Future vaccines: recent advances and future prospects

The 20th century has witnessed the introduction of over 20 vaccines that prevent or even conquer diseases such as smallpox, polio, and measles. The continued threat of infectious diseases demands the creation of many more vaccines, especially against common respiratory and gastrointestinal pathogens. Thanks to recent advances in molecular biology, immunology, and adjuvant technology, the next decade likely will bring a vaccine for HIV/AIDS also. We enter the 21st century with a tempered optimism, proud of past achievements, but mindful of the challenges that lie ahead.

Predictors of influenza virus vaccination status in hospitalized children

OBJECTIVE

To determine predictors of influenza virus vaccination status in children who are hospitalized during the influenza season.

METHODS

A cross-sectional study was conducted among children who were hospitalized with fever between 6 months and 3 years of age or with respiratory symptoms between 6 months and 18 years of age. The 1999 to 2000 influenza vaccination status of hospitalized children and potential factors that influence decisions to vaccinate were obtained from a questionnaire administered to parents/guardians.

RESULTS

Influenza vaccination rates for hospitalized children with and without high-risk medical conditions were 31% and 14%, respectively. For both groups of children, the vaccination status was strongly influenced by recommendations from physicians. More than 70% of children were vaccinated if a physician had recommended the influenza vaccine, whereas only 3% were vaccinated if a physician had not. Lack of awareness that children can receive the influenza vaccine was a commonly cited reason for nonvaccination.

CONCLUSIONS

A minority of hospitalized children with high-risk conditions had received the influenza vaccine. However, parents' recalling that a clinician had recommended the vaccine had a positive impact on the vaccination status of children.

The safety of inactivated influenza vaccine in adults and children with asthma

BACKGROUND

Influenza causes substantial morbidity in adults and children with asthma, and vaccination can prevent influenza and its complications. However, there is concern that vaccination may cause exacerbations of asthma.

METHODS

To investigate the safety of the inactivated trivalent split-virus influenza vaccine in adults and children with asthma, we conducted a multicenter, randomized, double-blind, placebo-controlled, cross-over trial in 2032 patients with asthma (age range, 3 to 64 years). The order of injection of vaccine and placebo was assigned randomly, with a mean of 22 days between the injections. Each day during the two weeks after each injection, the patients recorded peak expiratory flow rates, symptoms thought to be related to the injection, use of asthma medications, unscheduled health care visits for asthma, and asthma-related absences from school or work. The primary outcome measure was an exacerbation of asthma in the two weeks after the injections.

RESULTS

The frequency of exacerbations of asthma was similar in the two weeks after the influenza vaccination and after placebo injection (28.8 percent and 27.7 percent, respectively; absolute difference, 1.1 percent; 95 percent confidence interval, -1.4 percent to 3.6 percent). The exacerbation rates were similar in subgroups defined according to age, severity of asthma, and other factors. Among symptoms thought to be associated with the injection, only body aches were more frequent after the vaccine injection than after placebo injection (25.1 percent vs. 20.8 percent, P<0.001).

CONCLUSIONS

The inactivated influenza vaccine is safe to administer to adults and children with asthma, including those with severe asthma. Given the morbidity of influenza, all those with asthma should receive the vaccine annually.

Efficacy of a cold-adapted, intranasal, equine influenza vaccine: challenge trials

A randomised, controlled, double-blind, influenza virus, aerosol challenge of horses was undertaken to determine the efficacy of a cold-adapted, temperature sensitive, modified-live virus, intranasal, equine influenza vaccine. Ninety 11-month-old influenza-naïve foals were assigned randomly to 3 groups (20 vaccinates and 10 controls per group) and challenged 5 weeks, 6 and 12 months after a single vaccination. Challenges were performed on Day 0 in a plastic-lined chamber. Between Days 1 and 10, animals were examined daily for evidence of clinical signs of influenza. Nasal swabs for virus isolation were obtained on Day 1 and Days 1 to 8 and blood samples for serology were collected on Days 1, 7 and 14. There was no adverse response to vaccination in any animal. Following challenge at 5 weeks and 6 months, vaccinates had significantly lower clinical scores (P = 0.0001 and 0.005, respectively), experienced smaller increases in rectal temperature (P = 0.0008 and 0.0007, respectively) and shed less virus (P<0.0001 and P = 0.03, respectively) over fewer days (P<0.0001 and P = 0.002, respectively) than did the controls. After the 12 month challenge, rectal temperatures (P = 0.006) as well as the duration (P = 0.03) and concentration of virus shed (P = 0.04) were significantly reduced among vaccinated animals. The results of this study showed that 6 months after a single dose of vaccine the duration and severity of clinical signs were markedly reduced amongst vaccinated animals exposed to a severe live-virus challenge. Appropriate use of this vaccine should lead to a marked reduction in the frequency, severity and duration of outbreaks of equine influenza in North America.

Vaccines for pneumonia and new antiviral therapies

Influenza and pneumococcal diseases are preventable to a large extent. The Health Care Financing Agency of Medicare and the Joint Commission on Accreditation of Healthcare Organizations have made prevention of these two diseases a top priority. Immunization should remain the primary tool for prevention. When influenza epidemics appear, practitioners should be aware that effective drugs are available to treat influenza A or B if given promptly after the onset of illness.

Nasal immunization with subunit proteosome influenza vaccines induces serum HAI, mucosal IgA and protection against influenza challenge

The immunogenicity of a mucosally delivered subunit influenza vaccine was assessed in mice. Split influenza virus vaccine (sFlu) was formulated with proteosomes (Pr-sFlu), administered intranasally, and the induced immunity was compared with the responses elicited by sFlu alone given either intramuscularly or intranasally. Intranasal (i.n.) immunization with Pr-sFlu induced specific serum IgG and hemagglutination inhibition (HAI) titers comparable to or better than those induced by intramuscular (i.m.) sFlu, and in contrast to sFlu alone, i.n. Pr-sFlu also induced high levels of influenza-specific IgA in lung and nasal washes. Mice receiving i.n. Pr-sFlu were completely protected against live virus challenge, as were mice immunized by injection with sFlu alone. The i.n. Pr-sFlu elicited cytokine responses polarized towards a type 1 phenotype whereas those elicited by sFlu alone were of a mixed type 1/type 2 phenotype. The data strongly suggest that i.n. proteosome-formulated influenza antigens are highly effective and are excellent candidates for a non-invasive human vaccine.