Vittorio Demicheli

Azienda Sanitaria Locale Alessandria, Alessandria, Piedmont, Italy

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Publications (20)191.92 Total impact

  • Source
    Article: Vaccines for preventing influenza in healthy children.
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    ABSTRACT: The consequences of influenza in children and adults are mainly absenteeism from school and work. However, the risk of complications is greatest in children and people over 65 years of age. To appraise all comparative studies evaluating the effects of influenza vaccines in healthy children, assess vaccine efficacy (prevention of confirmed influenza) and effectiveness (prevention of influenza-like illness (ILI)) and document adverse events associated with influenza vaccines. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 3) which includes the Acute Respiratory Infections Group's Specialised Register, OLD MEDLINE (1950 to 1965), MEDLINE (1966 to November 2011), EMBASE (1974 to November 2011), Biological Abstracts (1969 to September 2007), and Science Citation Index (1974 to September 2007). Randomised controlled trials (RCTs), cohort and case-control studies of any influenza vaccine in healthy children under 16 years of age. Four review authors independently assessed trial quality and extracted data. We included 75 studies with about 300,000 observations. We included 17 RCTs, 19 cohort studies and 11 case-control studies in the analysis of vaccine efficacy and effectiveness. Evidence from RCTs shows that six children under the age of six need to be vaccinated with live attenuated vaccine to prevent one case of influenza (infection and symptoms). We could find no usable data for those aged two years or younger.Inactivated vaccines in children aged two years or younger are not significantly more efficacious than placebo. Twenty-eight children over the age of six need to be vaccinated to prevent one case of influenza (infection and symptoms). Eight need to be vaccinated to prevent one case of influenza-like-illness (ILI). We could find no evidence of effect on secondary cases, lower respiratory tract disease, drug prescriptions, otitis media and its consequences and socioeconomic impact. We found weak single-study evidence of effect on school absenteeism by children and caring parents from work. Variability in study design and presentation of data was such that a meta-analysis of safety outcome data was not feasible. Extensive evidence of reporting bias of safety outcomes from trials of live attenuated influenza vaccines (LAIVs) impeded meaningful analysis. One specific brand of monovalent pandemic vaccine is associated with cataplexy and narcolepsy in children and there is sparse evidence of serious harms (such as febrile convulsions) in specific situations. Influenza vaccines are efficacious in preventing cases of influenza in children older than two years of age, but little evidence is available for children younger than two years of age. There was a difference between vaccine efficacy and effectiveness, partly due to differing datasets, settings and viral circulation patterns. No safety comparisons could be carried out, emphasising the need for standardisation of methods and presentation of vaccine safety data in future studies. In specific cases, influenza vaccines were associated with serious harms such as narcolepsy and febrile convulsions. It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months of age in the USA, Canada, parts of Europe and Australia. If immunisation in children is to be recommended as a public health policy, large-scale studies assessing important outcomes, and directly comparing vaccine types are urgently required. The degree of scrutiny needed to identify all global cases of potential harms is beyond the resources of this review. This review includes trials funded by industry. An earlier systematic review of 274 influenza vaccine studies published up to 2007 found industry-funded studies were published in more prestigious journals and cited more than other studies independently from methodological quality and size. Studies funded from public sources were significantly less likely to report conclusions favourable to the vaccines. The review showed that reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies. The content and conclusions of this review should be interpreted in the light of this finding.
    Cochrane database of systematic reviews (Online) 01/2012; 8:CD004879. · 5.72 Impact Factor
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    Article: Vaccines for measles, mumps and rubella in children.
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    ABSTRACT: Mumps, measles and rubella (MMR) are serious diseases that can lead to potentially fatal illness, disability and death. However, public debate over the safety of the trivalent MMR vaccine and the resultant drop in vaccination coverage in several countries persists, despite its almost universal use and accepted effectiveness. To assess the effectiveness and adverse effects associated with the MMR vaccine in children up to 15 years of age. For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 2), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, PubMed (July 2004 to May week 2, 2011) and Embase.com (July 2004 to May 2011). We used comparative prospective or retrospective trials assessing the effects of the MMR vaccine compared to placebo, do nothing or a combination of measles, mumps and rubella antigens on healthy individuals up to 15 years of age. Two review authors independently extracted data and assessed methodological quality of the included studies. One review author arbitrated in case of disagreement. We included five randomised controlled trials (RCTs), one controlled clinical trial (CCT), 27 cohort studies, 17 case-control studies, five time-series trials, one case cross-over trial, two ecological studies, six self controlled case series studies involving in all about 14,700,000 children and assessing effectiveness and safety of MMR vaccine. Based on the available evidence, one MMR vaccine dose is at least 95% effective in preventing clinical measles and 92% effective in preventing secondary cases among household contacts.Effectiveness of at least one dose of MMR in preventing clinical mumps in children is estimated to be between 69% and 81% for the vaccine prepared with Jeryl Lynn mumps strain and between 70% and 75% for the vaccine containing the Urabe strain. Vaccination with MMR containing the Urabe strain has demonstrated to be 73% effective in preventing secondary mumps cases. Effectiveness of Jeryl Lynn containing MMR in preventing laboratory-confirmed mumps cases in children and adolescents was estimated to be between 64% to 66% for one dose and 83% to 88% for two vaccine doses. We did not identify any studies assessing the effectiveness of MMR in preventing rubella.The highest risk of association with aseptic meningitis was observed within the third week after immunisation with Urabe-containing MMR (risk ratio (RR) 14.28; 95% confidence interval (CI) from 7.93 to 25.71) and within the third (RR 22.5; 95% CI 11.8 to 42.9) or fifth (RR 15.6; 95% CI 10.3 to 24.2) weeks after immunisation with the vaccine prepared with the Leningrad-Zagreb strain. A significant risk of association with febrile seizures and MMR exposure during the two previous weeks (RR 1.10; 95% CI 1.05 to 1.15) was assessed in one large person-time cohort study involving 537,171 children aged between three months and five year of age. Increased risk of febrile seizure has also been observed in children aged between 12 to 23 months (relative incidence (RI) 4.09; 95% CI 3.1 to 5.33) and children aged 12 to 35 months (RI 5.68; 95% CI 2.31 to 13.97) within six to 11 days after exposure to MMR vaccine. An increased risk of thrombocytopenic purpura within six weeks after MMR immunisation in children aged 12 to 23 months was assessed in one case-control study (RR 6.3; 95% CI 1.3 to 30.1) and in one small self controlled case series (incidence rate ratio (IRR) 5.38; 95% CI 2.72 to 10.62). Increased risk of thrombocytopenic purpura within six weeks after MMR exposure was also assessed in one other case-control study involving 2311 children and adolescents between one month and 18 years (odds ratio (OR) 2.4; 95% CI 1.2 to 4.7). Exposure to the MMR vaccine was unlikely to be associated with autism, asthma, leukaemia, hay fever, type 1 diabetes, gait disturbance, Crohn's disease, demyelinating diseases, bacterial or viral infections. The design and reporting of safety outcomes in MMR vaccine studies, both pre- and post-marketing, are largely inadequate. The evidence of adverse events following immunisation with the MMR vaccine cannot be separated from its role in preventing the target diseases.
    Cochrane database of systematic reviews (Online) 01/2012; 2:CD004407. · 5.72 Impact Factor
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    Article: Vaccines for preventing cholera: killed whole cell or other subunit vaccines (injected).
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    ABSTRACT: Injected cholera vaccines are rarely used today, although they may have some benefit. It is valuable to summarize the evidence for effectiveness of injected cholera vaccines for comparison with newer oral vaccines (subject of a separate Cochrane Review). To evaluate killed whole cell (KWC) cholera vaccines and other inactive subunit vaccines (administered by injection) for preventing cholera and death, and to evaluate the adverse effects. In September 2008, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2008, Issue 3), EMBASE, and LILACS. We also searched reference lists and handsearched the journal Vaccine up to 1997. Randomized and quasi-randomized controlled trials comparing injected cholera vaccines (KWC or other inactive subunit) with placebo, control vaccines, or no intervention in adults and children irrespective of immune status or special risk category. Two authors extracted data and assessed trial methodological quality independently. Dichotomous data were reported using the risk ratio (RR) with 95% confidence intervals (CI). Vaccine efficacies were also calculated (% vaccine efficacy = (1-RR) x 100%). Sixteen trials, involving over one million adults, children and infants, fulfilled the inclusion criteria. Twenty-four comparisons reported on vaccine efficacy (cholera cases and/or deaths) and 11 comparisons considered adverse effects (nine reported on both). Compared to placebo, vaccinees had a reduced risk of death from cholera (RR 0.49, 95% CI 0.25 to 0.93; 837,442 participants) and a reduced risk of contracting cholera at 12 months (RR 0.52, 95% CI 0.42 to 0.65, random-effects model; 1,512,573 participants). This translates to an efficacy of 48%, 95% confidence interval 35% to 58%. Significant protection lasted for two years, even after only a single dose, and for three years with an annual booster. Children over five years and adults were protected for up to three years, while children under five years were protected for up to a year. Injected cholera vaccines were associated with more systemic and local adverse effects compared to placebo, but these were not severe or life-threatening. Injected cholera vaccines appear to be safe and relatively more effective than usually realized. Protection against cholera persists for up to two years following a single dose of vaccine, and for three years with an annual booster. However, they have been superseded by oral vaccines.
    Cochrane database of systematic reviews (Online) 01/2010; · 5.72 Impact Factor
  • Article: Vaccines for preventing tick-borne encephalitis.
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    ABSTRACT: Tick-borne encephalitis (TBE) is a disease of the central nervous system caused by a tick-borne viral infection. TBE can lead to severe neurological syndromes such as meningitis, meningoencephalitis, and meningoencephalomyelitis, which can result in death. There is no treatment, and prevention with the vaccine is the only intervention currently available. To evaluate vaccines for preventing TBE in terms of effectiveness and adverse effects. In June 2008, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2008, Issue 2), MEDLINE, EMBASE, LILACS, and mRCT. We also checked reference lists of articles. Randomized and quasi-randomized controlled trials comparing TBE vaccines against placebo, control vaccines, no intervention, or a different dose or schedule of the intervention vaccine. Two authors applied the inclusion criteria, extracted data, and assessed each trial's risk of bias. We could not combine the included trials in a meta-analysis because of differences in comparisons and outcomes. Eleven trials (corresponding to 10 papers) involving 8184 participants (6586 adults and 1598 children) were included. Different versions of three types of TBE vaccines were tested (IPVE, FSME-IMMUN, and Encepur); out of which only three (Encepur children, Encepur Adults, and FSME-IMMUN "new") are currently licensed. No trials reported on cases of clinical TBE, but all reported on antibody titre (seroconversion). All the vaccines gave seroconversion rates of over 87%. Systemic and local adverse effects were common; none were severe or life threatening. Tick-borne encephalitis vaccines appear to be highly immunogenic, but the relationship between seroconversion and clinical protection has not been established. Although adverse effects were commonly reported, none were serious or life threatening.
    Cochrane database of systematic reviews (Online) 02/2009; · 5.72 Impact Factor
  • Article: Influenza vaccination for elderly people and their care workers.
    Tom Jefferson, Vittorio Demicheli
    The Lancet 07/2007; 369(9576):1857-8. · 38.28 Impact Factor
  • Article: Incidence of vaccine preventable pneumococcal invasive infections and blood culture practices in Italy.
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    ABSTRACT: In order to estimate the incidence of invasive pneumococcal diseases (IPD) and the amount of vaccine preventable serious infections, a 1-year population-based surveillance was undertaken in two comparable Italian regions (Piemonte and Puglia, representing 14% of the Italian population) prospectively collecting data and strains from all the hospital microbiological laboratories. A retrospective analysis of hospital discharge records, matched with the laboratory database, was also undertaken in nine hospitals in these two regions to determine the frequency of use of blood cultures and its impact on IPD incidence estimate. For children under 2 years of age, the incidence rates of IPD were 11.3 per 100,000 and 5.9 per 100,000 in Piemonte and in Puglia, respectively; for subjects 65 years of age and over the incidence rates were 5.7 per 100,000 and 0.2 per 100,000, in the two regions, respectively. The number of blood cultures performed was six times higher in Piemonte than that in Puglia. About 96% of isolates from IPD patients, aged 65 years and over, belonged to serogroups included in the 23-valent polysaccharide vaccine, whereas about 79% of strains isolated from patients under 5 years of age were related to serotypes included in the 7-valent conjugate vaccine. The estimate of the incidence of IPD is affected greatly by the different attitudes in performing blood cultures, especially in older patients. In Italy, bacteriological culture procedures should be undertaken more frequently to provide decision-makers with reliable estimates of serious vaccine preventable conditions.
    Vaccine 04/2005; 23(19):2494-500. · 3.77 Impact Factor
  • Article: Selective quotation of evidence in vaccines research.
    Tom Jefferson, Deirdre Price, Vittorio Demicheli, Elvira Bianco
    The Lancet 06/2004; 363(9422):1738. · 38.28 Impact Factor
  • Article: Balancing benefits and harms in health care: observational data on harm are already included in systematic reviews.
    Tom Jefferson, Vittorio Demicheli
    BMJ (Clinical research ed.). 10/2003; 327(7417):750.
  • Source
    Article: Unintended events following immunization with MMR: a systematic review.
    Tom Jefferson, Deirdre Price, Vittorio Demicheli, Elvira Bianco
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    ABSTRACT: Public debate over the safety of the trivalent measles, mumps and rubella (MMR) vaccine and the drop in vaccination rates in several countries persists despite its almost universal use and accepted effectiveness. We carried out a systematic review to assess the evidence of unintended effects (beneficial or harmful) associated with MMR and the applicability of systematic reviewing methods to the field of safety evaluation. Eligible studies were comparative prospective or retrospective on healthy individuals up to 15 years of age, carried out or published by 2003. We identified 120 articles satisfying our inclusion criteria and included 22. MMR is associated with a lower incidence of upper respiratory tract infections, a higher incidence of irritability, similar incidence of other adverse effects compared to placebo and is likely to be associated with benign thrombocytopenic purpura (TP), parotitis, joint and limb complaints and aseptic meningitis (mumps Urabe strain-containing MMR). Exposure to MMR is unlikely to be associated with Crohn's disease, ulcerative colitis, autism or aseptic meningitis (mumps Jeryl-Lynn strain-containing MMR). The design and reporting of safety outcomes in MMR vaccine studies, both pre- and post-marketing, are largely inadequate. The evidence of adverse events following immunization with MMR cannot be separated from its role in preventing the target diseases.
    Vaccine 10/2003; 21(25-26):3954-60. · 3.77 Impact Factor
  • Article: The effectiveness and safety of hepatitis A vaccine: a systematic review.
    Vittorio Demicheli, Donatella Tiberti
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    ABSTRACT: We report on the conduct of a systematic review to assess the efficacy and the safety of hepatitis A vaccines in adults and children. We identified, retrieved, and assessed all trials evaluating the effects of hepatitis A vaccines on prevention of cases of hepatitis A, death from hepatitis A, and assessing nature and frequency of adverse events. We included eight randomised trials, four containing efficacy outcomes, three containing only safety outcomes and a single study containing efficacy and adverse events outcomes. Combined inactivated vaccine effectiveness was 86% (95% CI: 63-95%). Combined attenuated vaccine effectiveness was 95% (95% CI: 81-99%). Inactivated vaccine effectiveness in the prevention of HAV secondary cases, compared to non-intervention was 82% (95% CI: 23-96%). Safety profile of vaccines was similar to that of their comparators. Despite poor design and reporting of trials, we found convincing evidence of the effectiveness and safety of inactivated HAV vaccines.
    Vaccine 07/2003; 21(19-20):2242-5. · 3.77 Impact Factor
  • Article: The use of hepatitis a vaccination in Italy: an economic evaluation.
    Vittorio Demicheli, Emanuela Carniglia, Stefania Fucci
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    ABSTRACT: We report on the conduct and results of an economic model of two different strategies of vaccination against hepatitis A in Italy. In strategy 1 (universal vaccination), all newborns are vaccinated simultaneously with MMR at 15 months and all 12 year olds are vaccinated with combined hepatitis A and B vaccine. In strategy 2 (contacts' vaccination) only subjects with a close social and spatial relationship with the sick are vaccinated. In strategy 1 costs per avoided case and net costs per avoided case values are always very high. Net costs become very low when newborns and 12 year olds are vaccinated, and become negative (indicating a potential gain) when 12 year olds are vaccinated. From an economic viewpoint, universal vaccination appears recommendable only in epidemic conditions. For strategy 2 our model shows that cost for avoidable case are very low and net costs for avoided case are always negative, showing the potential presence of an absolute benefit. We conclude that in Italy mass vaccination appears economically worthwhile only during epidemics but vaccination of contacts is an economically worthwhile routine measure.
    Vaccine 07/2003; 21(19-20):2250-7. · 3.77 Impact Factor
  • Article: Economic analysis of influenza vaccination and treatment.
    Tom Jefferson, Vittorio Demicheli
    Annals of internal medicine 05/2003; 138(7):607; author reply 608-9. · 16.73 Impact Factor
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    Article: Polysaccharide pneumococcal vaccines.
    Tom Jefferson, Vittorio Demicheli
    BMJ (Clinical research ed.). 09/2002; 325(7359):292-3.
  • Article: Educating Authors and Reviewers of Economic Evaluations of Health Care-Reply.
    Tom Jefferson, Vittorio Demicheli, Luke Vale
    JAMA The Journal of the American Medical Association 08/2002; 288(8):959. · 30.03 Impact Factor
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    Article: Quality of systematic reviews of economic evaluations in health care.
    Tom Jefferson, Vittorio Demicheli, Luke Vale
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    ABSTRACT: Reviews performed almost a decade ago showed considerable gaps in the quality of reporting and methods applied to economic evaluations of health care interventions. Measures taken by the research community to address the issue included the promulgation of guidelines and the publicizing of good practice in economic evaluation. To assess the quality of methods of systematic reviews, economic evaluations in health care, and reporting methods, we conducted full-text searches of private and public databases for the period 1990 through March 2001 and corresponded with researchers active in the field. A total of 102 reports were identified, but only 39 were included. Quality of systematic reviews was assessed by a 6-item checklist. Quality of review methods was reasonable, but more attention needs to be paid to search methods and standardization of evaluation instruments. The reviews found consistent evidence of serious methodological flaws in a significant number of economic evaluations. Lack of clear descriptions of methods, lack of explanation and justification for the framework and approach used, and low-quality estimates of effectiveness for the interventions evaluated were the most frequent flaws. Modest improvements in quality of conducting and reporting economic evaluations appear to have taken place in the last decade. Proper allocation of resources on the basis of economic evaluations remains uncertain. Editorial teams and regulatory bodies should perform quality assurance based on a single widely accepted and validated standard instrument.
    JAMA The Journal of the American Medical Association 07/2002; 287(21):2809-12. · 30.03 Impact Factor
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    Article: Quality of economic evaluations in health care.
    Tom Jefferson, Vittorio Demicheli
    BMJ (Clinical research ed.). 03/2002; 324(7333):313-4.
  • Article: [Conflict of interest in industry-funded medical research].
    Carlo Di Pietrantonj, Vittorio Demicheli
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    ABSTRACT: to assess the impact of the source of funding on the results of medical research. review of systematic reviews on this subject. relationship between source of funding and studies' conclusions. twenty reviews of studies dealing with many different medical intervention were identified and included. The definitions of the source of funding varied largely across the studies and the information on funding available in the primary studies were generally judged as inaccurate and insufficient to identify the source. Some studies assessed the relationship between funding and methodological quality of the research and found no difference between industry funded and other studies. The majority of the studies included demonstrated the existence of a significant association between source of funding and results of the research showing that the studies financed by industry are more likely to conclude in favour of the intervention produced by the funding bodies. A meta-analysis was carried out on 18 of the twenty studies. Pooled Relative Risk was 1.58 (95% CI: 1.39 to 1.80) confirming the existence of a significant association and homogeneous results across different studies. future reviews should seek for information regarding sources of funding of included studies and account for it in interpreting their results.
    Epidemiologia e prevenzione 29(2):85-95. · 0.65 Impact Factor
  • Chapter: Vaccines for measles, mumps and rubella in children
  • Chapter: Vaccines for measles, mumps and rubella in children
  • Article: Incidence of vaccine preventable pneumococcal invasive infections and blood culture practices in Italy
    [show abstract] [hide abstract]
    ABSTRACT: In order to estimate the incidence of invasive pneumococcal diseases (IPD) and the amount of vaccine preventable serious infections, a 1-year population-based surveillance was undertaken in two comparable Italian regions (Piemonte and Puglia, representing 14% of the Italian population) prospectively collecting data and strains from all the hospital microbiological laboratories. A retrospective analysis of hospital discharge records, matched with the laboratory database, was also undertaken in nine hospitals in these two regions to determine the frequency of use of blood cultures and its impact on IPD incidence estimate. For children under 2 years of age, the incidence rates of IPD were 11.3 per 100,000 and 5.9 per 100,000 in Piemonte and in Puglia, respectively; for subjects 65 years of age and over the incidence rates were 5.7 per 100,000 and 0.2 per 100,000, in the two regions, respectively. The number of blood cultures performed was six times higher in Piemonte than that in Puglia. About 96% of isolates from IPD patients, aged 65 years and over, belonged to serogroups included in the 23-valent polysaccharide vaccine, whereas about 79% of strains isolated from patients under 5 years of age were related to serotypes included in the 7-valent conjugate vaccine. The estimate of the incidence of IPD is affected greatly by the different attitudes in performing blood cultures, especially in older patients. In Italy, bacteriological culture procedures should be undertaken more frequently to provide decision-makers with reliable estimates of serious vaccine preventable conditions.
    Vaccine.