Piero Luigi Lai

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.

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.

Cost-benefit evaluation of influenza vaccination in the elderly in the Italian region of Liguria

Influenza causes considerable morbidity and mortality and the damage to public health can be considerable. The most effective measures available for the prevention of influenza is vaccination. In most industrialised countries the objective of vaccination is to limit the disease among individuals at risk, especially the elderly. During the winter of 2000/2001, General Practitioners (GPs) monitored 14,818 elderly individuals. The objective was to evaluate the weekly incidence of the disease. Furthermore, we carried out a prospective study on 512 elderly individuals, arranged according to vaccination (304 vaccinated and 208 non-vaccinated), with the main objective of assessing the costs of the disease and the efficacy of vaccination. Finally, in order to assess the percentage of vaccinated elderly individuals, we carried out a telephone survey on 500 subjects. Our clinical surveillance study enabled us to establish that morbidity was particularly low in elderly individuals.The results of the prospective study allowed us to estimate the cost-benefit ratio at 8.22, with a net saving of 110.20 Euros for each vaccinated subject. We were also able to establish that the vaccine coverage among elderly individuals was 63%. Our study, though carried out during a low epidemic year, confirms the economic advantage of vaccination in the elderly.

Anamnestic response to administration of purified non-adsorbed hepatitis B surface antigen in healthy responders to hepatitis B vaccine with long-term non-protective antibody titres

A clinical trial with four groups receiving either 0.6, 3.5, 10 or 20 micro g of purified non-adsorbed hepatitis B surface antigen (HBsAg) was performed to study the kinetics as well as the capacity of the immune memory to respond following exposure to HBsAg in responders to a complete course of hepatitis B vaccine, in whom anti-HBs titres had declined below the seroprotective level. The study population included 64 healthy individuals. All response parameters seropositivity, seroprotection rates, booster response rates and geometric mean titres (GMTs), consistently showed that the immune response was highly satisfactory and dose-dependent. A remarkable immune response was obtained even with a trace amount of HBsAg. This study further supports recent indication that booster hepatitis B vaccine doses may be unnecessary in healthy adult responders to a full course of hepatitis B vaccination.

Sexual behaviour and risk factors for the acquisition of human papillomavirus infections in young people in Italy: suggestions for future vaccination policies

BackgroundHuman Papillomavirus (HPV) is the most common sexually transmitted infection. The main risk factors correlated with HPV infection are: early sexual debut, the number of partners, frequency and type of sexual contact and partner’s sexual histories.We surveyed sexual habits among young people in order to provide information that might orient decision-makers in adopting HPV multi-cohort vaccination policies.MethodsWe administered a questionnaire to students (14–24 years old) in five Italian cities.Results7298 questionnaires were analyzed (4962 females and 2336 males); 55.3% of females (95% CI 53.9–56.7) and 52.5% of males (95% CI 50.5–54.5) reported regular sexual activity. The mean age at sexual debut was 15.7 ± 1.6 and 15.6 ± 1.6 for females and males, respectively, and the median age was 16 for both sexes.With regard to contraceptive use during the last year, 63.6% of males and 62.8% of females responded affirmatively; 42.6% of males and 42.8% of females used condoms.ConclusionThe results reveal precocious sexual activity among respondents, with the mean age at first intercourse declining as age decreases. Condom use proved to be scant. Considering lifestyle-related risk factors, males appear to have a higher probability of acquiring HPV infection than females.These data support the importance of promoting multi-cohort HPV vaccination strategies for females up to 25 years of age. It is essential to improve vaccination coverage through different broad-spectrum strategies, including campaigns to increase awareness of sexually transmitted diseases and their prevention.

Burden of the 1999-2008 seasonal influenza epidemics in Italy: comparison with the H1N1v (A/California/07/09) pandemic.

Despite preventive efforts, seasonal influenza epidemics are responsible for substantial morbidity and mortality every year worldwide, including developed countries. The A/H1N1v pandemic imposed a considerable healthcare and economic burden. In order to obtain an accurate estimate of the economic burden of influenza, and hence to guide policy-makers effectively, systematic studies are necessary. To this end, data from epidemiological surveillance are essential. To estimate the impact of the 1999-2008 seasonal influenza epidemics and the H1N1v pandemic, we analyzed data from the Italian Influenza Surveillance System (CIRINET). In the period 1999-2008, the Italian surveillance network consisted of sentinel general practitioners and pediatricians, who reported cases of Influenza-Like Illness (ILI) and Acute Respiratory Infections (ARI) observed during their clinical practice from mid-October to late April each year; reports were sent to the Center for Research on Influenza and other Viral Infections (CIRI-IV). CIRI-IV receives data from 9 of the 20 Italian Regions: Liguria, Abruzzo, Calabria, Friuli Venezia Giulia, Lombardy, Puglia, Sicily, Tuscany and Umbria. Previous estimates of influenza case costs were used in economic evaluations. Clinical-epidemiological and Virological surveillance of the seasonal epidemics from 1999-2008 showed that the highest epidemic period was 2004-2005, when a new variant of the H3N2 influenza virus subtype emerged (A/California/07/04). Indeed, the highest peak of morbidity in the decade occurred in February 2005 (12.6 per 1,000 inhabitants). In 1999-2008, H1N1 subtype strains circulated, and co-circulated with strains belonging to the H3N2 subtype and B type. Regarding B viruses in 2001-02, viruses belonged to the B/Victoria/02/07 lineage re-emerged, and in subsequent years co-circulated with viruses belonging to the B/Yamagata/lineage. The estimated costs of seasonal epidemics from 1999-2008 in Italy ranged from €15 to €20 billion, and the costs of the H1N1v pandemic ranged from €1.3 to €2.3 billion. This Italian study yields interesting conclusions: the results of Influenza surveillance in several developed countries vary markedly; influenza imposes a considerable social, healthcare and economic burden; most cases that occurred during the pandemic involved subjects under 14 years of age, and, although the clinical course of H1N1v influenza was usually mild, the related economic burden was heavy.

An overview of current and potential use of information and communication technologies for immunization promotion among adolescents

Information and communication technologies (ICT), such as the Internet or mobile telephony, have become an important part of the life of today’s adolescents and their main means of procuring information. The new generation of the Internet based on social-networking technologies, Web 2.0, is increasingly used for health purposes by both laypeople and health professionals. A broad spectrum of Web 2.0 applications provides several opportunities for healthcare workers, in that they can reach large numbers of teenagers in an individualized way and promote vaccine-related knowledge in an interactive and entertaining manner. These applications, namely social-networking and video-sharing websites, wikis and microblogs, should be monitored in order to identify current attitudes toward vaccination, to reply to vaccination critics and to establish a real-time dialog with users. Moreover, the ubiquity of mobile telephony makes it a valuable means of involving teenagers in immunization promotion, especially in developing countries.