Factors associated with hepatitis B virus immunization coverage at the beginning of a population campaign in the Lazio region, Italy

Background. The hepatitis B virus (HBV) vaccination was introduced in Italy in 1991 as compulsory among newborns and among 11-year-old children. Methods. We conducted a retrospective study to evaluate the HBV immunizatio n coverage of the two target populations by the public health services in t he Lazio region and to analyze factors associated with starting and complet ing HBV immunization in the initial period of the campaign. We used data re gistered in the public health services of 7/51 Health Districts. As a proxy indicator of services' performance we used the "expected immunization peri od," that is, the 6-month period in which each child should have been start ed on immunization, according to the calendar. Results. HBV vaccine coverage rates were 63% in the younger cohort and 50% in the older one. The results of univariate and multivariate regression ana lysis showed that starting HBV immunization was associated with being newbo rn (crude OR = 3.30; 95%CI 2.17-2.44), with living in a small city (crude O R = 6.81; 95%CI 6.12-7.58), and with being assigned to the second (crude OR = 1.77; 95%CI 1.65-1.90) or to the third 6-month period of the expected im munization period (crude OR = 2.58; 95%CI 2.42-2.76). The probability of co mpleting HBV immunization was higher among children who had had the first d ose "age-appropriately" or with "acceptable delay" and among those living i n small cities. It was lower among children in the second or the third 6-mo nth period. Size of urban area of residence was associated with both outcom es: the city of Rome showed the lowest probabilities of starting and comple ting HBV immunization, while the small cities showed the highest Conclusions. The performance of public health services was the most importa nt determinant of recourse to public health services for vaccinations; it v aried according to size of urban area; in towns organization difficulties c ontributed to the delay of starting vaccination, for at least a year. The e xpected immunization period was a good proxy indicator of services' perform ance. The timing of the first dose was the strongest predictor of completin g vaccination also at the beginning of the campaign. (C) 2001 American Heal th Foundation and Academic Press.