Paolo Durando

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

Colistin and rifampicin in the treatment of multidrug-resistant Acinetobacter baumannii infections

OBJECTIVES The increased incidence of nosocomial infections by multidrug-resistant organisms has motivated the re-introduction of colistin in combination with other antimicrobials in the treatment of infections. We describe the clinical and microbiological outcomes of patients infected with multidrug-resistant Acinetobacter baumannii who were treated with a combination of colistin and rifampicin. PATIENTS AND METHODS Critically ill patients with pneumonia and bacteraemia caused by A. baumannii resistant to all antibiotics except colistin in medical and surgical intensive care units were enrolled. Clinical and microbiological responses and safety were evaluated. RESULTS Twenty-nine patients (47 +/- 14 years and APACHE II score 17.03 +/- 3.68), of whom 19 were cases of nosocomial pneumonia and 10 were cases of bacteraemia, were treated with intravenous colistin sulphomethate sodium (2 million IU three times a day) in addition to intravenous rifampicin (10 mg/kg every 12 h). All A. baumannii isolates were susceptible to colistin. The mean duration of treatment with intravenous colistin and rifampicin was 17.7 (+/-10.4) days (range 7-36). Clinical and microbiological responses were observed in 22 of 29 cases (76%) and the overall infection-related mortality was 21% (6/29). Three of the 29 evaluated patients (10%) developed nephrotoxicity when treated with colistin, all of whom had previous renal failure. No cases of renal failure were observed among patients with normal baseline renal function. No neurotoxicity was noted. CONCLUSIONS Colistin and rifampicin appears to be an effective and safe combination therapy for severe infections due to multidrug-resistant A. baumannii.

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.

Novel Approach To Reduce the Hepatitis C Virus (HCV) Window Period: Clinical Evaluation of a New Enzyme-Linked Immunosorbent Assay for HCV Core Antigen

ABSTRACT The window period in hepatitis C virus (HCV) infection is still a major problem in ensuring blood safety. HCV RNA detection by nucleic acid amplification technology-based tests has contributed to reduce the infectivity of blood products, but it is expensive, time-consuming and affected by a high prevalence of false-positive results. The aim of this study was to assess the performance of a newly developed enzyme immunoassay for the detection of HCV core antigen and its suitability for use in the screening of blood units in order to identify infecting samples that do not contain specific antibodies. For evaluation of laboratory performance, different samples were selected: to evaluate specificity, we tested 2,586 sera from blood donors, 500 general population samples, and 58 “difficult sera”. All samples were tested by two screening assays, and results were negative. To estimate clinical sensitivity, 103 HCV RNA-positive, anti-HCV-negative samples, 6 natural seroconversion panels, and 9 commercial seroconversion panels were tested. Intra- and interassay precision were determined on two HCV-RNA-positive, anti-HCV-negative sera. Seventeen (0.66%) blood donor samples, 2 (0.4%) general population samples, and 2 (3.44%) difficult sera were initially reactive; 3 sera were positive on repetition. These 21 samples tested by reverse transcription-PCR were negative. The clinical sensitivity calculated with seroconversion panels and seroconverted patient samples was very similar to PCR sensitivity: 95% of PCR-positive, antibody-negative samples contained detectable HCV antigen. Data on intra- and interassay precision showed dispersion indices with values of less than 10%. In conclusion, the HCV antigen assay showed high sensitivity and specificity and could become a useful means of improving the safety of blood and blood products.

Universal childhood immunisation against Streptococcus pneumoniae: The five-year experience of Liguria Region, Italy

Liguria was the first Italian Administrative Region, since 2003, to actively recommend free-of-charge immunisation, of all infants, with heptavalent Pneumococcal Conjugate Vaccine (PCV-7), within a research pilot-project. Vaccination coverage among infants rapidly increased from 42.8% in 2003 to 83.3% in 2004, progressively reaching levels of 93.4% in 2007. Two scientific projects have been carried out, aimed: (i) to assess the immunogenicity of PCV-7 and of a hexavalent vaccine Diphtheria-Tetanus-Trivalent Acellular Pertussis-Hepatitis B-Inactivated Polio Virus-Haemophilus influenzae type B (DTaP-HBV-IPV-Hib) when co-administered to healthy infants at 3, 5 and 11-12 months of age (routine schedule), and (ii) to evaluate the effect of the immunisation campaign in preventing pneumococcal-associated hospitalisations. Results in 151 infants showed the high immunogenicity of the vaccines, seroprotection rates, measured 1 month after the third dose, ranging between 97.3% (serotype 6 B) and 100% (serotypes 4 and 9 V) for PCV-7 and between 99.3% and 100% against common antigens of hexavalent vaccine. Monitoring nearly 70,000 children, aged 0-24 months, during the period 2000-2007, and comparing hospitalisation rates occurred in subjects belonging to birth cohorts before and after the introduction of widespread immunisation, a significant decline for all-cause and pneumococcal pneumonia and for acute otitis media was observed, with preventive fractions of 15.2%, 70.5% and 36.4%, respectively.

MF59-adjuvanted vaccine: a safe and useful tool to enhance and broaden protection against seasonal influenza viruses in subjects at risk.

Importance of the field: Vaccination is universally considered as the most effective tool for the prevention of influenza, which represents a significant burden, both from a health-care and a socio-economic viewpoint. Conventional non-adjuvanted vaccines have shown suboptimal immunogenicity in the elderly, in patients with serious chronic diseases or the immunocompromised and in young children. The protection offered by non-adjuvanted vaccines may be further reduced by periodic antigenic drifts. Areas covered in this review: Between the several strategies proposed to address the need for more immunogenic vaccines than the conventional ones, the most successful strategy is represented by the use of adjuvants. Since 1997, an MF59-adjuvanted subunit influenza vaccine has been licensed in several countries and used in the elderly worldwide. Available data on the safety, immunogenicity and effectiveness of this vaccine have been reported and discussed in details. What the reader will gain: The MF59-adjuvanted vaccine has been shown to enhance immunogenicity and to confer cross-reactivity against heterologous influenza viral strains in the elderly, in adults with serious underlying medical conditions and in healthy infants and young children. Furthermore, its effectiveness has been demonstrated in older adults, reducing hospitalizations for pneumonia, cardiovascular and cerebrovascular diseases. Take home message: The vaccine is safe, with an acceptable tolerability profile, thus representing a valid option to optimize the control of seasonal influenza.

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.

Impaired Response to Influenza Vaccine Associated with Persistent Memory B Cell Depletion in Non-Hodgkin’s Lymphoma Patients Treated with Rituximab-Containing Regimens

Influenza vaccination is generally recommended for non-Hodgkin’s lymphoma (NHL) patients, but no data are available about the activity of this vaccine after treatment with rituximab-containing regimens. We evaluated the humoral response to the trivalent seasonal influenza vaccine in a group of NHL patients in complete remission for ≥6 mo (median, 29 mo) after treatment with rituximab-containing regimens (n = 31) compared with age-matched healthy subjects (n = 34). B cell populations and incidence of influenza-like illness were also evaluated. For each viral strain, the response was significantly lower in patients compared with controls and was particularly poor in patients treated with fludarabine-based regimens. In the patient group, the response to vaccination did not fulfill the immunogenic criteria based on the European Committee for Medicinal Products for Human Use requirements. Among the patients, CD27+ memory B cells were significantly reduced, and their reduction correlated with serum IgM levels and vaccine response. Episodes of influenza-like illness were recorded only in patients. These results showed that NHL patients treated with rituximab-containing regimens have persisting perturbations of B cell compartments and Ig synthesis and may be at particular risk for infection, even in long-standing complete remission.

Adjuvants and alternative routes of administration towards the development of the ideal influenza vaccine

Vaccination is universally considered as the principal measure for the control of influenza, which represents a significant burden worldwide, both from a health-care and a socio-economic viewpoint. Conventional non-adjuvanted trivalent influenza vaccines (TIVs) have been recognized as having some deficiencies, such as suboptimal immunogenicity particularly in the elderly, in patients with severe chronic diseases and immunocompromized, indeed, those groups of the population at higher risk of developing severe complications following influenza infection, when compared to healthy adults. Moreover, the protection offered by conventional vaccines may be reduced by periodic antigenic drifts, resulting in a mismatch between the circulating and vaccinal viral strains. Another gap regarding currently available vaccines is related to the egg-based manufacturing system for their production: not only the length of time involved with the latter but also the limited capacity of this platform technology represent a major limitation for the active prevention of influenza, which is particularly important in the case of a new pandemic strain. New technologies used in vaccine composition, administration and manufacture have led to major advances during the last few years, and clinical researchers have continued to work hard, investigating several different strategies to improve the performance of influenza vaccines: namely, the addition of different adjuvants (i.e., MF59- and AS03-vaccines, virosomal formulations), the use of alternative routes of administration or manufacture (i.e., intradermal, nasal and oral vaccines and cell culture- and reverse genetic-based vaccines) or of high doses of antigen, and the development of DNA-vaccines, or the use of conserved viral epitopes (i.e., the extracellular portion of the M2 protein, the nucleoprotein and some domains of the hemagglutinin), in the attempt to produce a “universal target” antigen vaccine. The knowledge acquired represents a fundamental challenge for the control of influenza. An overview of the most recent and interesting results, some of which gained from our own research experience, particularly concerning two successful approaches, of those outlined above, namely the use of: (i) the oil-in-water MF59-adjuvant, and (ii) the intradermal (ID) route for vaccine administration, through a novel microinjection system, will be reported and discussed, together with the possible implications and perspectives to optimize immunization policies against influenza in the near future.

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.