A. E. Tozzi

Persistence of protection through 33 months of age provided by immunization in infancy with two three-component acellular pertussis vaccines

A large, randomized, placebo-controlled clinical trial in Italy on two three-component pertussis vaccines, given as DTaP in infancy, one manufactured by SmithKline and Beecham (SB) and one by Chiron Biocine (CB), found each vaccine to be 84% efficacious through the average age of 24 months. The cohort of children enrolled in the trial was followed with unmodified case ascertainment procedures for nine additional calendar months, during which partial unblinding occurred, for the unvaccinated randomized group. For the DTaP groups, the specific vaccine assignment remained double-blinded throughout the entire additional observation period. Pertussis was defined as paroxysmal cough lasting at least 21 days and confirmed by culture or serology. In the additional 9 months the observed absolute efficacy was 78% (95% CI, 62-87%) for SB DTaP vaccine and 89% (95% CI, 79-94%) for CB DTaP. The relative risk of developing pertussis in SB DTaP recipients compared to CB DTaP vaccinees was 1.99 (95% CI, 1.13-3.51). By combining observations from the initial and additional follow-up periods, the overall observed vaccine efficacy through an average age of 33 months of SB DTaP was 80% and of CB DTaP, 85%.

Immunization coverage and timeliness of vaccination in Italian children with chronic diseases

Since children with chronic diseases represent a primary target for immunization strategies, it is important that their immunization coverage and timeliness of vaccines is optimal. We performed a study to measure immunization coverage and timeliness of vaccines in children with type 1 diabetes, HIV infection, Down syndrome, cystic fibrosis, and neurological diseases. A total of 275 children aged 6 months-18 years were included in the study. Coverage for diphtheria-tetanus-pertussis (DTP), polio (Pol), and hepatitis B (HBV) vaccines approximated 85% at 24 months, while measles-mumps-rubella (MMR) coverage was 62%. Immunization coverage for seasonal influenza was 59%. The analysis of timeliness revealed that there was heterogeneity among children with different chronic diseases. A proportional hazard model showed that children with HIV infection had the longest time to complete three doses of DTP, Pol, and HBV, and those with neurological diseases received the first dose of MMR later than the other categories. Causes of missing or delayed vaccination mostly included a concurrent acute disease. Children with chronic diseases should be strictly monitored for routine and recommended vaccinations, and health care providers and families should be properly informed to avoid false contraindications.

Risk factors for poor renal prognosis in children with hemolytic uremic syndrome

Many factors have been proposed as predictors of poor renal prognosis in children with hemolytic uremic syndrome (HUS), but their role is still controversial. Our aim was to detect the most reliable early predictors of poor renal prognosis to promptly identify children at major risk of bad outcome who could eventually benefit from early specific treatments, such as plasmapheresis. Prognostic factors identifiable at onset of HUS were evaluated by survival analysis and a proportional hazard model. These included age at onset, prodromal diarrhea (D), leukocyte count, central nervous system (CNS) involvement, and evidence of Shiga toxin-producing Escherichia coli (STEC) infection. Three hundred and eighty-seven HUS cases were reported; 276 were investigated for STEC infection and 189 (68%) proved positive. Age at onset, leukocyte count, and CNS involvement were not associated with the time to recovery. Absence of prodromal D and lack of evidence of STEC infection were independently associated with a poor renal prognosis; only 34% of patients D−STEC− recovered normal renal function compared with 65%–76% of D+STEC+, D+STEC− and D−STEC+ patients. In conclusion, absence of both D and evidence of STEC infection are needed to identify patients with HUS and worst prognosis, while D– but STEC+ patients have a significantly better prognosis.

Reactogenicity in the elderly of nine commercial influenza vaccines : results from the Italian SVEVA study

A 10-fold increase of reported adverse events following influenza vaccination in the 1995-1996 campaign was reported. To evaluate the relative reactogenicity of different influenza vaccines a prospective observational study was conducted in 72 Italian local health units (LHU) in the period October-December 1996. Of the 16,637 enrolled individuals aged 65 or more, 27.4% reported the occurrence of at least one adverse event within 72 h of vaccination. The odds ratios, adjusted through a multivariate logistic model, were highest for whole vaccine recipients. Most of the observed events were of moderate clinical severity and were mainly represented by local symptoms. None of the products was found to show an unusual or concerning reactogenicity profile, and no severe events associated with immunization were reported.

Effectiveness of an intervention program in reducing postoperative infections

From 1987 to 1989, the National Health Institute carried out a before and after intervention study in order to evaluate the effectiveness of active surveillance and of modification of patient care practices in reducing the incidence of postoperative infections. The initial study population consisted of 20 general and thoracic surgical wards in 12 hospitals; 11 wards were not able to complete the study and were therefore excluded from the analysis. In December 1988, after a 13-month period in which baseline infection rates were assessed in 4,096 patients, written protocols regarding modification of patient care practices were defined and applied. Effectiveness of intervention was evaluated comparing infection rates measured in a 6-month period in 1989 on 1,638 operated patients with those of the previous period. In the overall population, a reduction of 19% of nosocomial infections was observed after the intervention. When individual infection sites were considered, pneumonia rates were statistically significantly reduced by 39%; for the other infection sites the observed differences were not significant. Effectiveness of intervention varied by subgroups of wards. In three of the studied wards, surgical wound infections were significantly reduced by 72%, whereas in the remaining wards the intervention seemed to have no positive impact on infection rates. Nevertheless, the intervention seemed to have been effective in increasing the awareness of infection problems in two other wards. Results of the study suggest that a consistent reduction of postoperative infections can be achieved in surgical wards where usual patient-care practices differ from standard of patient care policies. Nevertheless, the observed variation in effectiveness of intervention by individual wards suggests that differences in structural and behavioral characteristics can affect the compliance with recommended standards.

Impact of a regional Hib vaccination programme in Italy

In the Veneto region of Italy, a coverage of 26% for Haemophilus influenzae type b (Hib) primary vaccination in 1-year-old children plus a 31-53% catch-up coverage in children 1-4 years of age resulted in a 91% reduction of Hib invasive disease in children <5 years of age. These data suggest that vaccination of older children can contribute substantially to herd immunity, even in settings where primary vaccination is low. Since a single Hib vaccine dose is efficacious in preventing Hib invasive disease in children over 1 year of age, and the costs of vaccination are reduced, catch-up should always be considered when introducing Hib vaccine in routine immunization programmes.

Predictors of adverse events after the administration of acellular and whole-cell diphtheria-tetanus-pertussis vaccines

Recurrence of adverse events, the effect of site of injection, and concurrent administration of oral polio vaccine (OPV) and hepatitis B vaccine (HBV) on reactogenicity were assessed in recipients of two acellular pertussis vaccines given in combination with diphtheria and tetanus toxoids (DTaP), one whole-cell DTP vaccine (DTPwc) and one DT vaccine during a double blind, randomized, controlled clinical trial. Local and systemic side reactions were more likely to recur after the administration of DTaP and DT compared with DTPwc. In all vaccine groups, injection in the buttock was associated with a lower rate of common adverse events compared with injection in the thigh, while simultaneous administration of OPV and/or HBV did not increase the risk of onset of side reactions.

Role of non-polio enterovirus infection in pediatric hemolytic uremic syndrome

Abstract. Verocytotoxin-producing Escherichia coli (VTEC) infections cause most cases of hemolytic uremic syndrome (HUS); 10–30% of patients, however, are negative for VTEC infection. The etiology of HUS in VTEC-negative cases remains poorly understood. Before the association between VTEC infection and HUS was recognized, sporadic cases of HUS with enterovirus infection were reported in the literature. Since May 1988, most cases of HUS in Italy have been reported to the Italian surveillance system, and in 73% of these, evidence of VTEC infection was demonstrated. The aim of this study was to determine whether the frequency of enteroviral infections was different in the acute phase of VTEC-positive and VTEC-negative HUS. Eighty-nine patients were investigated for enteroviral infection, of whom 58 were VTEC positive and 31 VTEC negative. Two serum samples from each patient were examined for seroconversion to enterovirus (coxsackie, echovirus, and picornavirus) by a complement fixation test. Serological evidence of acute infection with non-polio enterovirus was found in 33 patients (37%) [20/58 (34.5%) VTEC positive and 13/31 (41.9%) VTEC negative]. There was no statistically significant difference between the two groups. These results demonstrate that there are no significant differences for enteroviral infection in VTEC-positive and VTEC-negative patients and, therefore, enteroviral infections should not be considered a cause of HUS in VTEC-negative children.

Haemophilus influenzae Invasive Disease in Italy, 1997–1998

The following members comprise the Haemophilus influenzae Study Group: Istituto Superiore di Sanità, Laboratorio di Epidemiologia e Biostatistica: P. Carbonari; Associazione Microbiologi Clinici Italiani (AMCLI): P. Nicoletti, A. Goglio; Regione Piemonte: A. Ruggenini Moiraghi, S. Orecchia, A. Castella, C. Zotti; Provincia Autonoma di Trento: V. Carraro, I. Caola, A. Calì; Regione Liguria: P. Crovari, C. Giordano, P. Tixi, M. Lemmi; Regione Toscana: P. Bonanni, A. Tomei, P. Pecile, E. Balocchini, L. Pecori; Regione Campania: F. Santonastasi, L. Cafaro, V. Pagano; Regione Puglia: S. Barbuti, M. Chironna Haemophilus influenzae Invasive Disease in Italy, 1997–1998

Reactogenicity of a three-dose pertussis acellular vaccine catch-up in children 21-40 months of age

The reactogenicity of a three-dose catch-up acellular pertussis (aP) immunization of children at 21-40 months of age was evaluated. Vaccination was well-tolerated: fever > or = 38 degrees C was reported after 5% of administered doses and local reactions after 14-15%. The onset of adverse events was not associated with age at vaccination, interval between doses or previous presence of antibodies against pertussis, whereas injection in sites other than the buttock and presence of the same symptom after a previous dose were associated with higher reactogenicity. Because of the good safety profile of primary aP immunization in children > 1 year of age, catch-up vaccination campaigns could be considered in areas where pertussis whole-cell vaccination uptake has been low and where the number of susceptible children should be reduced to control pertussis circulation.