Teresa Pozzi

Increased immunogenicity of the MF59-adjuvanted influenza vaccine compared to a conventional subunit vaccine in elderly subjects.

Three-hundred and eight outpatient elderly subjects (≥ 65 years) were randomly assigned to receive the MF59-adjuvanted influenza vaccine (FLUAD; n = 204) or a conventional subunit influenza vaccine (AGRIPPAL S1; n = 104) in order to compare the safety and immunogenicity of the two vaccines. Although mild pain at the injection site was reported more frequently by subjects immunised with the adjuvanted vaccine, both vaccines were shown to be safe and well tolerated. The adjuvanted vaccine was more immunogenic as indicated by higher post-immunisation geometric mean titres (GMTs) and by higher proportions of subjects with post-immunisation ≥ four fold increases of antibody titres or subjects with ≥ 1/160 post-immunisation HI titres. These differences, statistically significant for all three strains after immunisation, indicated that, by addition of the MF59 adjuvant emulsion, conventional subunit influenza antigens acquire an enhanced immunogenicity without any clinically significant increase of their reactogenicity.

Flucelvax (Optaflu) for seasonal influenza

Conventional egg-based manufacturing technology for seasonal influenza vaccines has several drawbacks, including its inflexibility, reliance on egg supplies, risk of contamination, absence of growth of some isolates and egg-adaptive viral mutations that threaten vaccine matching. To overcome these limitations, cell culture-derived vaccines have been designed, including the trivalent inactivated vaccine Flucelvax®/Optaflu® (brand names in the US/EU, respectively). Flucelvax/Optaflu has gained wide regulatory approval and is currently implemented in several countries. Non-clinical studies have assuaged hypothetical concerns regarding oncogenicity and use in persons allergic to dogs. Ample clinical data suggest the non-inferiority of Flucelvax/Optaflu to egg-based vaccines in terms of immunogenicity, safety and tolerability, and it has fulfilled American and European mandatory requirements. Although Flucelvax/Optaflu is currently indicated only for adults and the elderly, pediatric data indicate its good immunogenicity and safety. This paper provides an update on the clinical development of Flucelvax/Optaflu, its seasonal trials and available post-marketing surveillance data.

Prevalence of diphtheria toxin antibodies in human sera from a cross-section of the Italian population

A polycentric study was carried out between 1993 and 1995 in order to evaluate diphtheria immunity on a representative sample of population from different areas of Italy. To determine diphtheria antitoxin, sera from 5187 apparently healthy subjects, divided according to sex and age groups, were titrated using an ELISA indirect method. A basic protective titre of diphtheria antitoxin (> 0.01 IU ml-1) was found in 4080 (78.6%) subjects. No statistically significant differences between males and females were observed. Our findings show that the proportion of susceptibles increases with age and a high proportion of adults no longer has diphtheria antitoxin at protective levels since toxigenic C. diphtheriae circulation is presently lacking in Italy.

Immunity to diphtheria in Siena

The aim of this study, carried out in 1993, was to evaluate diphtheria immunity in Siena. Diphtheria antitoxin levels were measured by means of the immunoenzymatic test (ELISA) in serum samples of 602 apparently healthy subjects (239 males and 363 females) of all ages residing in Siena. According to widely used criteria, 6% of the total population were susceptible to diphtheria (antibody levels < 0.01 IU/ml), 71% had basic protection (0.01-0.09 IU/ml) and 23% were fully protected (> or = 0.1 IU/ml). The results suggested that a high proportion of young population had a protective level of immunity against diphtheria, that susceptibility increased with age and a smaller proportion of males (2.9%) than females (8.3%) were unprotected; this difference was statistically significant. Our results suggest that it may be useful to revaccinate adults with low levels of diphtheria toxoid so that the percentage that remains unprotected does not put the community at risk of an outbreak of diphtheria.

Egg-Independent Influenza Vaccines and Vaccine Candidates

Vaccination remains the principal way to control seasonal infections and is the most effective method of reducing influenza-associated morbidity and mortality. Since the 1940s, the main method of producing influenza vaccines has been an egg-based production process. However, in the event of a pandemic, this method has a significant limitation, as the time lag from strain isolation to final dose formulation and validation is six months. Indeed, production in eggs is a relatively slow process and production yields are both unpredictable and highly variable from strain to strain. In particular, if the next influenza pandemic were to arise from an avian influenza virus, and thus reduce the egg-laying hen population, there would be a shortage of embryonated eggs available for vaccine manufacturing. Although the production of egg-derived vaccines will continue, new technological developments have generated a cell-culture-based influenza vaccine and other more recent platforms, such as synthetic influenza vaccines.

Prevalence of streptococcus mutans and dental decay in school children from Siena (Italy)

Epidemiological indexes of dental decay and prevalence of Streptococcus mutans in dental plaque were studied in a group of 255 schoolchildren aged 6–11 from a suburban area near Siena (Italy). Mutans streptococci were isolated from 17.4% of subjects: a significant correlation with dental decay indexes and with the presence of active caries was observed.

Valutazione benefici-costi della vaccinazione antinfluenzale negli anziani in due stagioni epidemiche a confronto nella provincia di Siena

SummaryObjective: To carry out a survey on anti-influenza vaccination coverage and effectiveness in elderly people, and to evaluate its cost-benefit ratio. Design and methods: We performed a cost-benefit analysis based on direct costs. A survey was carried out by means of a questionnaire (filled by General Practitioners with reference to a selected sample of elderly) during two different influenza seasons: 1999/2000 (characterised by an average epidemic), and 2000/2001 (small epidemic). Subjects were asked to provide info about personal data, vaccination status (including related costs) and (if they had got the flu) disease characteristics (i.e. drugs used, visits, hospitalisation). A unit cost was applied to the resources used. Results: A total of 496 subjects aged > 65 years responded in the first influenza season and 501 in the second. The cost-benefit ratio in the vaccinated population was 4.63 in the first season vs 3.58 in the second. Therefore, the saving for every vaccinated person was Lit. 93,167.6 and Lit. 70,738.3, respectively. Conclusions: The cost/benefit ratio was higher in the average epidemic season than in the low epidemic season because of the higher influenza incidence and the greater efficacy of vaccination (i.e. a greater number of prevented cases). Influenza vaccination seems to be advantageous in terms of cost-effectiveness and cost-benefit ratios, thus justifying the objective of reaching the highest possible coverage in elderly people.