Roberto Gasparini

MF59®-Adjuvanted H5N1 Vaccine Induces Immunologic Memory and Heterotypic Antibody Responses in Non-Elderly and Elderly Adults

Background Pathogenic avian influenza virus (H5N1) has the potential to cause a major global pandemic in humans. Safe and effective vaccines that induce immunologic memory and broad heterotypic response are needed. Methods and Findings Healthy adults aged 18–60 and >60 years (n = 313 and n = 173, respectively) were randomized (1∶1) to receive two primary and one booster injection of 7.5 μg or 15 μg doses of a subunit MF59-adjuvanted H5N1 (A/Vietnam/1194/2004) (clade 1) vaccine. Safety was monitored until 6 months after booster. Immunogenicity was assessed by hemagglutination inhibition (HI), single radial hemolysis (SRH) and microneutralization assays (MN). Mild injection-site pain was the most common adverse reaction. No serious adverse events relating to the vaccine were reported. The humoral immune responses to 7.5 μg and 15 μg doses were comparable. The rates for seroprotection (HI>40; SRH>25mm2; MN ≥40) after the primary vaccination ranged 72–87%. Six months after primary vaccination with the 7.5 μg dose, 18% and 21% of non-elderly and elderly adults were seroprotected; rates increased to 90% and 84%, respectively, after the booster vaccination. In the 15 μg group, seroprotection rates among non-elderly and elderly adults increased from 25% and 62% after primary vaccination to 92% and 88% after booster vaccination, respectively. A heterologous immune response to the H5N1/turkey/Turkey/05 strain was elicited after second and booster vaccinations. Conclusions Both formulations of MF59-adjuvanted influenza H5N1 vaccine were well tolerated. The European Union requirement for licensure for pre-pandemic vaccines was met by the lower dose tested. The presence of cross-reactive antibodies to a clade 2 heterologous strain demonstrates that this vaccine may be appropriate for pre-pandemic programs. Trial Registration ClinicalTrials.gov NCT00311480

Cross-protection by MF59-adjuvanted influenza vaccine: neutralizing and haemagglutination-inhibiting antibody activity against A(H3N2) drifted influenza viruses.

Adjuvants enhance antibody response against vaccination. We compared the ability of MF59-adjuvanted and non-adjuvanted subunit influenza vaccines, containing A/Wyoming/3/03(H3N2), to confer cross-protection against four consecutive drifted strains in the elderly. Neutralizing and haemagglutination-inhibiting antibody were measured. MF59-adjuvanted vaccine induced a stronger booster response against A/Panama/2007/99(H3N2) than non-adjuvanted vaccine. A/Panama/2007/99(H3N2) circulated widely during the previous 5 years and was included in vaccines over four consecutive seasons. Broader serological protection against drifted strains that circulated 1 and 2 years after vaccination with A/Wyoming/3/03(H3N2) was observed with MF59-adjuvanted vaccine. Thus, MF59-adjuvanted vaccine confers greater immunogenicity than non-adjuvanted vaccines in vulnerable populations.

Safety and immunogenicity of two influenza virus subunit vaccines, with or without MF59 adjuvant, administered to human immunodeficiency virus type 1-seropositive and -seronegative adults.

ABSTRACT The objective of this study was to evaluate and compare both the safety and tolerability and the humoral and cell-mediated immune responses for two influenza virus subunit vaccines, one with MF59 adjuvant (Fluad) and one without an adjuvant (Agrippal), in healthy and in human immunodeficiency virus type 1 (HIV-1)-infected adult individuals. To achieve this aim, an open, randomized, comparative clinical trial was performed during the 2005-2006 season. A total of 256 subjects were enrolled to receive one dose of vaccine intramuscularly. Blood samples were taken at the time of vaccination and at 1 and 3 months postvaccination. A good humoral antibody response was detected for both vaccines, meeting all the criteria of the Committee for Medical Products for Human Use. After Beyers correction for prevaccination status, Fluad exhibited better immunogenicity than Agrippal, as shown from the analysis of the geometric mean titers, with significant differences for some virus strains; however, no definitive conclusions on the clinical significance of such results can be drawn, because the method used to estimate antibody response is currently nonstandard for influenza virus vaccines. Significant induction of an antigen-specific CD4+ T-lymphocyte proliferative response was detected at all time points after immunization, for both the vaccines, among HIV-1-seronegative subjects. This was different from what was observed for HIV-1-infected individuals. In this group, significance was not reached at 30 days postvaccination (T30) for those immunized with Agrippal. Also when data were compared between treatment groups, a clear difference in the response at T30 was observed in favor of Fluad (P = 0.0002). The safety profiles of both vaccines were excellent. For HIV-1-infected individuals, no significant changes either in viremia or in the CD4+ cell count were observed at any time point. The results showed good safety and immunogenicity for both vaccines under study for both uninfected and HIV-1-infected adults, confirming current recommendations for immunization of this high-risk category.

Neisseria meningitidis B vaccines

Invasive infections caused by Neisseria meningitidis are a serious public health problem worldwide and have a heavy economic impact. The incidence of invasive disease due to Neisseria meningitidis is highly variable according to geographical area and serogroup distribution. Since the introduction of vaccination programs with conjugated vaccine C in children and adolescents, most cases of invasive meningococcal disease in developed countries have been caused by meningococcus B. It is important to underline that invasive meningococcal disease will not be controlled until safe and effective vaccines for meningococcal B are available and widely used. The aims of this article are to describe the most recent developments in meningococcal B vaccines and to discuss how these vaccines can contribute to containing meningococcal disease.

Epidemiology of tick-borne encephalitis (TBE) in Europe and its prevention by available vaccines

Tick-borne Encephalitis (TBE), which is caused by a Flavivirus, is the most common tick-transmitted disease in Central and Eastern Europe and Russia. Today, TBE is endemic in 27 European countries, and has become an international public health problem. The epidemiology of TBE is changing owing to various factors, such as improvements in diagnosis and case reporting, increased recreational activities in areas populated by ticks, and changes in climatic conditions affecting tick habitats. Vaccination remains the most effective protective measure against TBE for people living in risk zones, occupationally exposed subjects and travelers to endemic areas. The vaccines currently in use are FSME-Immun®, Encepur®, EnceVir® and TBE vaccine Moscow®. The numerous studies performed on the efficacy and safety of these vaccines have shown a high level of immunogenicity and an excellent safety profile. Several studies have also shown a high level of cross-protection among strains belonging to different subtypes. In the present paper we attempted to describe the continuously changing epidemiology of TBE in European States and to overview clinical development of available vaccines paying particular attention on cross-protection elicited by the vaccines.

Clinical and socioeconomic impact of seasonal and pandemic influenza in adults and the elderly

Influenza epidemics and pandemics carry a heavy socioeconomic burden. Hospitalization and treatment are more often necessary in high-risk patients, such as the elderly. However, the impact of influenza is not negligible even in adults, mainly because of lost productivity. The World Health Organization estimates that seasonal influenza causes 250,000–500,000 deaths worldwide each year; however, mortality may be very high in pandemic periods. Many estimates of the costs of seasonal influenza have been made in various socioeconomic contexts. For instance, among the adult population in Italy, a cost of €940.39 per case has been estimated. In the US, the average annual influenza burden in 18–49-y-old adults without underlying medical conditions is judged to include approximately 32,000 hospitalizations and 680 deaths. Estimating the influenza burden is a useful aid to determining the best influenza vaccination strategy and preventive and clinical treatments.

Meningococcal glycoconjugate vaccines

Neisseria meningitidis is a major cause of invasive bacterial infections worldwide. For this reason, efforts to control the disease have been directed at optimizing meningococcal vaccines and implementing appropriate vaccination policies. In the past, plain polysaccharide vaccines containing purified capsular polysaccharides A, C, Y and W135 were developed, but failed to protect infants, who are at greatest risk. Experience with the conjugate Haemophilus vaccine suggested that this approach might well empower meningococcal vaccines. Thus, a very efficacious vaccine against serogroup C Neisseria meningitis was optimized and has been widely used in developed nations since 1999. On the basis of epidemiological changes in the circulation of pathogenic serogroups in the United States, a quadrivalent conjugate vaccine against A, C, Y and W135 serogroups (Menactra™) has been developed and was approved by the U.S. FDA (Food and Drug Administration) in 2005. Recently, another tetravalent conjugate meningococcal vaccine (Menveo™) has been licensed and made available in the United States of America and in the European Union. Finally, in response to large epidemics caused by serogroup A meningococcus in Africa, a new, safe, immunogenic and affordable vaccine has been developed. This review highlights the evolution of conjugate meningococcal vaccines in general and discusses how this kind of vaccine can contribute to preventing meningococcal disease.

Effectiveness of a 23-valent polysaccharide vaccine in preventing pneumonia and non-invasive pneumococcal infection in elderly people: a large-scale retrospective cohort study.

This retrospective cohort study evaluated the effectiveness of a 23-valent pneumococcal polysaccharide vaccine in reducing hospital admission for pneumonia, otitis media and exacerbation of asthma or other syndromes due to Streptococcus pneumoniae in 9170 high-risk individuals. Cohort members were followed from 1 January 1998 to 31 December 2002. With regard to preventing hospitalization due to pneumonia, we observed a decrease in the incidence of 1/10 000 person-months and a reduction in the relative risk of 38% in the vaccinated cohort compared with the non-vaccinated subjects. A decrease in the risk of hospital admission for asthma, acute otitis media, chronic obstructive pulmonary disease and other respiratory infections was also observed in vaccinated compared with non-vaccinated subjects. The specificity of these findings was confirmed by the lack of a protective effect from vaccination for those outcomes, such as hospitalization ‘for all causes’ and ‘other otorhinolaryngological diagnoses’, that were not directly related to pneumococcal disease.

An overview on the implementation of HPV vaccination in Europe

The discovery that the Human PapillomaVirus (HPV) is the necessary cause of cervical cancer has led to the development of prophylactic vaccines. Cervical cancer is the second most common cause of death from cancer among young women in Europe: mortality is still high, despite its important reduction due to screening programs for early detection. Besides cervical cancer, HPV is responsible for a significant proportion of other anogenital cancers and an increasing number of oropharyngeal cancers, representing together an at least equal burden compared to cervical cancer. HPV is also responsible for conditions such as condyloma acuminata (genital warts) and recurrent respiratory papillomatosis. Organized vaccination programs against HPV have the potential to prevent about 70% of cervical cancers and the vast majority of the other HPV-related conditions. Recommendations for HPV vaccination of at least one cohort of females have been issued in nearly all western European countries, and national/regional publicly funded vaccination programs have been introduced in most of them. Different approaches have been chosen for the implementation of HPV vaccination, based on the organization of each countrys health care system. A brief outline of these programs in Europe is presented. As for all preventive public health interventions, high coverage of the target population with HPV vaccines pre-exposure is essential to achieve maximum reduction of cases: therefore, in order to obtain the maximum and most equitable coverage and future benefit, programs targeting adolescents before exposure to HPV should be preferred and population-based. Catch-up programs should also be implemented wherever possible, in order to deliver more and even earlier benefits, and effective communication strategies need to be adopted.

A heterologous MF59-adjuvanted H5N1 prepandemic influenza booster vaccine induces a robust, cross-reactive immune response in adults and the elderly.

ABSTRACT Immunogenicity and safety of a booster dose of an MF59-adjuvanted H5N1 vaccine containing 7.5 μg A/turkey/Turkey/1/2005-like (clade 2.2) H5N1 hemagglutinin, given approximately 18 months after primary vaccination with a heterologous strain, were evaluated. The booster vaccine was well tolerated and induced a robust, cross-reactive immune response.