Immunogenicity of hepatitis A-inactivated vaccine administered to seronegative infants, and serological follow-up 12 months after second dose.
ABSTRACT To evaluate a) the safety and immunogenicity of anti-HAV-inactivated vaccine administered during the first year of life to anti-HAV seronegative babies, and b) the antibody persistence in a low/intermediate endemic area.
After having obtained informed written consent from mothers, 92 babies were vaccinated at 4 and 10 mo of age. All babies were seronegative at birth and did not present HAV-RNA shedding in three serial stool samples taken at 1, 2 and 3 mo of age.
No general side effects (fever > 38 degrees C) were observed. After the first dose of vaccine, 70/82 (85.4%) babies developed anti-HAV > 10 mIU/ml and 36/82 (43.9%) > 20 mIU/ml. After the second dose of vaccine, all babies developed a titre > 20 mIU/ml, and GMT was 877 mIU/ml. After 1 y of follow-up, the decreasing rate was similar to that reported for adult populations. Furthermore, three babies doubled the titre observed 1 mo after the second dose, indicating the possible spread of HAV even in a low/intermediate endemic area.
Anti-HAV vaccine is safe, immunogenic and able to induce immune memory, and can be integrated into the routine infant immunization schedule during the first year of life.
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ABSTRACT: The molecular epidemiology of hepatitis A virus (HAV) was studied by analysing HAV strains recovered from environmental water samples over a 7 year period and strains recovered from patients with acute hepatitis over a 5 year period. A total of 54 samples of raw domestic sewage and 66 samples of river water were collected. HAV particles were concentrated and detected by nested RT-PCR. HAV infection in patients with acute hepatitis was serologically diagnosed in 26 of 74 serum samples, which were also analysed by nested RT-PCR. HAV RNA was detected in 57.4% of sewage samples, 39.2% of Llobregat river water samples, 20% of Ter river water samples and 61.6% of serum samples. The HAV genomes detected were characterized further by directly sequencing a region of the 5' non-translated region, the VP1/2A junction region and, in some samples, the 2B region. Results showed a 95% prevalence of genotype I, with nearly 50% being either subgenotype IA or subgenotype IB. Various strains were found simultaneously in both environmental and clinical samples. These strains were closely related to those described in distant geographical areas. Genotype IIIA was also found in 5% of sewage samples and in 12.5% of serum samples. Strains belonging to a common endemic genotype were not identified. The abundance of HAV in the environment produces a situation of sanitary risk, especially considering the low prevalence of antibodies in the young population.Journal of General Virology 01/2002; 82(Pt 12):2955-63. · 3.13 Impact Factor
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ABSTRACT: This study aimed to evaluate the incidence of and risk factors for acute viral hepatitis A (HAV) in Italy. Data were from a surveillance system for type-specific acute viral hepatitis (SEIEVA). To estimate the association of hepatitis A cases with the potential risk factors (Odds Ratios) and the proportion of all hepatitis A cases attributable to a given risk factor (population attributable risk), hepatitis B cases were used as controls. Independent predictors of HAV were estimated by conditional multiple logistic regression. During the period 1985-1994, 25553 viral hepatitis cases were reported. Of these, 6408 (25%) were due to hepatitis A (HAV). HAV incidence declined from 10/100000 in 1985 to 2/100000 in 1987. Since 1991, however, an increase in HAV has been observed. The majority of cases were 15-24 years old; the incidence was higher in males and in subjects residing in southern Italy. Only one death (0.02%) was observed. Shellfish consumption was the most frequently reported risk factor (62%). The proportion of cases reporting personal contact with an icteric case, travel to a high-medium endemic areas, and family contact with a child attending a day-care centre (household of day-care child) was 17%, 19% and 15%, respectively. The results of multivariate analysis showed that shellfish consumption (OR=2.6; 95% CI=2.4-2.9), travel to endemic areas for people residing in northern and central Italy (OR=5.4; 95% CI=4.6-6.2) and household of day-care child (OR=1.2; 95% CI=1.03-1.4), were all types of exposure independently associated with HAV. The estimates of population-attributable risk show that shellfish consumption explained as many as 42.2%, travel to high-medium endemic areas for people residing in northern and central Italy 24.2%, and household of day-care child only 1.4% of all acute hepatitis A cases in Italy. These findings indicate that HAV in Italy is mainly a food-borne disease. Vaccination against hepatitis A is strongly recommended for travellers to endemic areas.Journal of Hepatology 05/1997; 26(4):743-7. · 9.86 Impact Factor
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ABSTRACT: Several mechanisms have been suggested as mediating the inhibitory influence of maternal antibodies (MatAb) on infant responses. This inhibition is B cell determinant-specific, depends on the ratio between MatAb titers at the time of immunization and the dose of vaccine antigen, and leaves infant T cell responses largely unaffected. Neutralization of vaccine replication or FcgammaRIIB-mediated inhibitory signalling to infant B cells would not account for these characteristics. In contrast, determinant-specific masking of B cell epitopes and APC uptake of MatAb:vaccine antigen immune complexes, followed by antigen processing and presentation, explain the pattern of pre-clinical and clinical responses to infant vaccines. This allows the definition of the main determinants of the influence of MatAb on infant immunity.Vaccine 08/2003; 21(24):3406-12. · 3.49 Impact Factor