The impact of immigration and vaccination in reducing the incidence of hepatitis B in Catalonia (Spain).

BACKGROUND: The Hepatitis B virus (HBV) infection is a major cause of liver disease and liver cancer worldwide according to the World Health Organization. Following acute HBV infection, 1-5% of infected healthy adults and up to 90% of infected infants become chronic carriers and have an increased risk of cirrhosis and primary hepatocellular carcinoma. The aim of this study was to investigate the relationship between the reduction in acute hepatitis B incidence and the universal vaccination programme in preadolescents in Catalonia (Spain), taking population changes into account, and to construct a model to forecast the future incidence of cases that permits the best preventive strategy to be adopted. METHODS: Reported acute hepatitis B incidence in Catalonia according to age, gender, vaccination coverage, percentage of immigrants and the year of report of cases was analysed. A statistical analysis was made using three models: generalized linear models (GLM) with Poisson or negative binomial distribution and a generalized additive model (GAM). RESULTS: The higher the vaccination coverage, the lower the reported incidence of hepatitis B (p <0.01). In groups with vaccination coverage > 70%, the reduction in incidence was 2-fold higher than in groups with a coverage <70% (p <0.01). The increase in incidence was significantly-higher in groups with a high percentage of immigrants and more than 15% (p <0.01) in immigrant males of working age (19-49 years). CONCLUSIONS: The results of the adjusted models in this study confirm that the global incidence of hepatitis B has declined in Catalonia after the introduction of the universal preadolescent vaccination programme, but the incidence increased in male immigrants of working age. Given the potential severity of hepatitis B for the health of individuals and for the community, universal vaccination programmes should continue and programmes in risk groups, especially immigrants, should be strengthened.

Hepatitis A outbreaks in the vaccination era in Catalonia, Spain.

Hepatitis A outbreaks have a major impact on public health services and involve case investigation and intervention measures to susceptible contacts. At the end of 1998 a universal vaccination program with a combined hepatitis A+B vaccine was started in Catalonia (Spain) in 12-years-old preadolescents. The objective of this study was to compare the characteristics of hepatitis A outbreaks in the periods before and after the introduction of the preadolescent vaccination program and to estimate the preventable fraction of cases associated to outbreaks. The incidence rates of outbreaks, cases and hospitalization associated with each outbreak were calculated. Two periods were considered: before (1991-1998) and after (2000-2007) the introduction of mass vaccination. The preventable fraction and 95% confidence intervals (CI) of cases associated with outbreaks was calculated. The rate of associated cases with outbreaks was higher in the period before the vaccination program than in the post vaccination period (1.53 per 100,000 person-year vs 1.12 ; p< 0.001), but the rate of hospitalization was greater in the period after the introduction of vaccination program than in the period previous to vaccination (0.70 per million persons-year vs 0.08; p< 0.001). The preventable fraction of cases associated to outbreaks was 19.6%(95%CI 6.7-32.5) in the 0-4 years group and 16.7% (95% CI 6.0-27.5) in the 5-14 years group, but the highest figure (38.6%; 95%CI 21.3-55.9) was observed in the 15-24 years age group. The estimated proportion of cases associated with outbreaks that would theoretically have been prevented with the vaccination program suggests that substantial benefits have been obtained in Catalonia in people aged less than 25 years.

Parental knowledge of paediatric vaccination.

BACKGROUND: Although routine vaccination is a major tool in the primary prevention of some infectious diseases, there is some reluctance in a proportion of the population. Negative parental perceptions of vaccination are an important barrier to paediatric vaccination. The aim of this study was to investigate parental knowledge of paediatric vaccines and vaccination in Catalonia. METHODS: A retrospective, cross-sectional study was carried out in children aged < 3 years recruited by random sampling from municipal districts of all health regions of Catalonia. The total sample was 630 children. Parents completed a standard questionnaire for each child, which included vaccination coverage and knowledge about vaccination. The level of knowledge of vaccination was scored according to parental answers. RESULTS: An association was observed between greater vaccination coverage of the 4:4:4:3:1 schedule (defined as: 4 DTPa/w doses, 4 Hib doses, 4 OPV doses, 3 MenC doses and 1 MMR dose) and maternal age >30 years (OR: 2.30; 95% CI: 1.20-4.43) and with a knowledge of vaccination score greater than the mean (OR: 0.45; 95% CI: 0.28-0.72). The score increased with maternal educational level and in parents of vaccinated children.A total of 20.47% of parents stated that vaccines could have undesirable consequences for their children. Of these, 23.26% had no specific information and 17.83% stated that vaccines can cause adverse reactions and the same percentage stated that vaccines cause allergies and asthma. CONCLUSION: Higher vaccination coverage is associated with older maternal age and greater knowledge of vaccination.Vaccination coverage could be raised by improving information on vaccines and vaccination.

[Evaluation of mass vaccination programmes: the experience of Hepatitis A in Catalonia]. / Evaluación del impacto de los programas de vacunación masiva: la experiencia de la hepatitis A en Cataluña.

BACKGROUND: The hepatitis A + B vaccination programme of preadolescents was introduced in 1998 in Catalonia. During the following years, one of the main objectives has been to quantify the reduction in the incidence of hepatitis A caused by the vaccination programme. METHODS: A retrospective analysis applying the space-time scan statistic to reported incidence rates of hepatitis A was carried out in the counties of Catalonia from 1992 to 2007. The relative risk (RR) was calculated and the spatial autocorrelation was estimated using Moran's I statistic. RESULTS: Six of the 7 space-time clusters identified by the scan statistic occurred in the pre-vaccine era (1992-1998) and only one in the post-vaccine era (1992-2007). In the first 10 four-weekly periods of the post-vaccine era (1999-2005) there was a significant reduction in the incidence of hepatitis A in Catalonia with respect to the pre-vaccine era (1992-1998) (p<0,01). CONCLUSIONS: Moran's I statistic showed no pattern of global spatial dependence and was useful in detecting local clusters. These results corroborate previous studies that attributed most of the reduction in the incidence of hepatitis A in Catalonia to the effect of vaccination.

Vaccine Failures in Patients Properly Vaccinated with 13-Valent Pneumococcal Conjugate Vaccine in Catalonia, a Region with Low Vaccination Coverage.

Vaccine failures occurring with 13-valent pneumococcal conjugate vaccine (PCV13) in 3 pediatric hospitals in Barcelona (2012-2013) are described. PCV13 vaccine failure was defined as the occurrence of an invasive pneumococcal infection in children properly vaccinated by PCV13. Among 84 patients with invasive pneumococcal infection, 32 had received at least one dose of PCV13. Seventeen of them had invasive pneumococcal infection produced by a PCV13 serotype. Among those, 9 patients were considered to have a PCV13 vaccine failure. Serotype 3 was isolated in 6 patients, serotype 19A in 2 and serotype 6B in 1.

Results of the rubella elimination program in Catalonia (Spain), 2002-2011.

Rubella is usually a mild disease with nonspecific symptoms, but can cause congenital rubella syndrome (CRS) when infection occurs during pregnancy. The objective of this study was to evaluate the sensitivity and positive predictive value of different data sources used for surveillance purposes in the Rubella Elimination Program of Catalonia between 2002 and 2011. The Urgent Notification to the Statutory Disease Reporting System, the Individualized Disease Reporting System, screening for other viruses included in the Measles Elimination Program, the Microbiological Reporting System and the Minimum Hospital Discharge Data were evaluated. 100 suspected cases of postnatal rubella and 6 suspected cases of CRS were detected. For postnatal rubella, Urgent Notification had the highest sensitivity (32.5%; 95%CI 18.6-49.1), followed by the Virus screening in Measles Elimination Program (25%; 95%CI 12.7-41.2). Virus screening in the Measles Elimination Program had the highest PPV (76.9%; 95%CI 46.1-94.9), followed by the Individualized Disease Reporting System (57.1%; 95%CI 28.9-82.3). For CRS cases, the Individualized Disease Reporting System had the highest sensitivity (100%, 95%CI 29.2-100) and the highest PPV (60%; 95%CI 14.7-100). Most confirmed postnatal cases (25 cases, 48.1%) were in the 25-44 y age group followed by the 15-24 y age group (11 cases, 21.2%). The highest values of sensitivity and PPV for the detection of confirmed cases corresponded to activities that were specifically introduced in the measles and rubella elimination programs.

Are risk factors associated with invasive pneumococcal disease according to different serotypes?

The aim of this study was to investigate risk factors for the most common serotypes of invasive pneumococcal disease (IPD). A total of 293 IPD cases were analyzed in children aged 3-59 mo in a community with intermediate vaccination coverage with the 7-valent pneumococcal vaccine (PCV7). IPD cases were reviewed during 2007-2009 in two pediatric hospitals in Catalonia (Spain). A multivariate analysis using unconditional logistic regression was performed to estimate the adjusted odds ratio. PCV7 coverage was 45.4%. Pneumonia with empyema (64.5%) was the most frequent clinical manifestation. The most common serotypes were: serotype 1 (21.2%), 19A (16.0%), 3 (12.6%) and 7F/A (6.8%). 70.0% of serotypes found were included in the 13-valent conjugate vaccine (PCV13), 39.2% in the 10-valent conjugate vaccine and 8.1% in the PCV7. PCV7 was protective in IPD cases due to PCV7-serotypes (aOR: 0.15, 95% CI:0.04-0.55). Serotype 1 was positively associated with attending day care or school (aOR: 3.55, 95% CI: 1.21-10.38) and age 24-59 mo (aOR: 7.70, 95% CI:2.70-21.98). Serotype 19A was positively associated with respiratory infection in the previous month (aOR: 2.26, 95% CI: 1.03-4.94), non-penicillin susceptible IPD (aOR: 1.89, 95% CI:1.13-3.16) and negatively associated with age 24-59 mo (aOR: 0.19, 95% CI:0.09-0.41). Serotype 3 was positively associated with vaccination (aOR: 4.87, 95% CI:2.05-11.59). No factors were associated with serotype 7F/A. Vaccination with pneumococcal vaccines including more serotypes may reduce the risk of disease in our setting.

Effectiveness of measles vaccination for control of exposed children.

The effectiveness of measles vaccine for postexposure prophylaxis at educational centers was investigated. A total of 166 children who shared the classroom with 10 confirmed cases during the infectious period of cases were studied. Of total susceptible exposed children, 72% (54/75) were vaccinated and 25 contracted measles. Vaccine effectiveness in children vaccinated within 72 hours of exposure was 90.5% (95% confidence interval, 34%-99%).

Influenza vaccine coverage, influenza-associated morbidity and all-cause mortality in Catalonia (Spain).

The objective of this work was to study the behaviour of influenza with respect to morbidity and all-cause mortality in Catalonia, and their association with influenza vaccination coverage. The study was carried out over 13 influenza seasons, from epidemiological week 40 of 1994 to week 20 of 2007, and included confirmed cases of influenza and all-cause mortality. Two generalized linear models were fitted: influenza-associated morbidity was modelled by Poisson regression and all-cause mortality by negative binomial regression. The seasonal component was modelled with the periodic function formed by the sum of the sinus and cosines. Expected influenza mortality during periods of influenza virus circulation was estimated by Poisson regression and its confidence intervals using the Bootstrap approach. Vaccination coverage was associated with a reduction in influenza-associated morbidity (p<0.001), but not with a reduction in all-cause mortality (p=0.149). In the case of influenza-associated morbidity, an increase of 5% in vaccination coverage represented a reduction of 3% in the incidence rate of influenza. There was a positive association between influenza-associated morbidity and all-cause mortality. Excess mortality attributable to influenza epidemics was estimated as 34.4 (95% CI: 28.4-40.8) weekly deaths. In conclusion, all-cause mortality is a good indicator of influenza surveillance and vaccination coverage is associated with a reduction in influenza-associated morbidity but not with all-cause mortality.

MMR vaccine effectiveness in an outbreak that involved day-care and primary schools.

OBJECTIVE: In 2006, a large measles outbreak occurred in Catalonia (Spain), where the immunization schedule included two doses of MMR vaccine at 15 months and 4 years. The aim of this study was to investigate the vaccine effectiveness (VE) of MMR in children attending day-care and pre-school centres and to estimate the number of cases that would have been avoided by administering the first dose of MMR at 12 months. METHODS: A retrospective cohort study was carried out between October 2006 and January 2007 in day-care and pre-school centres with confirmed measles cases. VE was calculated in children aged ≥15 months without previous measles infection. Cases avoided by advancing the first dose of MMR to 12 months were estimated by calculating the basic and effective reproduction number in centres where transmission outside the class was observed. RESULTS: Fifteen centres and 1394 children were included. There were 77 confirmed cases (attack rate=5.5%). Vaccination coverage of the 1121 children aged ≥15 months was 91.6% and VE was 96% (95%CI 89-98%). There were 33 (41%) cases in the 81 children aged 12-14 months. Advancing the first dose to 12 months would have prevented 74 cases (91.5%) and lowered the attack rate from 41% to 8.6%. CONCLUSIONS: Over 90% of cases in children aged 12-14 months would have been avoided by MMR administration at 12 rather than 15 months. We strongly recommend advancing the first dose of MMR to 12 months in order to reduce the risk of measles outbreaks.

Epidemiology of pertussis in a country with high vaccination coverage.

INTRODUCTION: Pertussis has been a preventable disease in Catalonia since 1965, but the annual number of cases remains high. The aim of this study was to analyze the epidemiology of pertussis in Catalonia and its implications for control purposes. METHODS: An epidemiological study was carried out in Catalonia between 2004 and 2008. Pertussis cases reported to the Department of Health were collected and disease reports were filled out with the case information. Incidence rates, rate ratios (RR) and their 95% confidence intervals (CI) were calculated. RESULTS: 963 cases were reported: 555 (57.6%) were confirmed and 408 (42.4%) were suspected cases. The reported incidence rate was 2.01 × 10(-5) person years in 2004 and 4.34 in 2008. The biggest increase in cases between 2004 and 2008 was observed in the ≥35 years age group (RR: 6.98; 95%CI: 2.11-36.36). 303 (31.5%) patients were hospitalized, of whom 93.7% were aged <1 year. Clinical differences were observed in paroxysmal cough (83.8% in suspected and 76.4% in confirmed cases, p=0.005), posttussive vomiting (47.1% and 36.1%, respectively, p=0.001), apnoea (13.7% and 21.3%, respectively, p=0.003) and fever (20.1% and 12.4%, respectively, p=0.001). CONCLUSION: Pertussis incidence rates increased during the study period, with the greatest increase occurring in the ≥35 years age group. A booster dose of vaccine in young people could reduce the circulation of B. pertussis in adolescents and adults and indirectly reduce the incidence in children.

Effectiveness of 7-valent pneumococcal conjugate vaccine in the prevention of invasive pneumococcal disease in children aged 7-59 months. A matched case-control study.

The aim of this study was to evaluate the effectiveness of the administration of the 7-valent pneumococcal conjugate vaccine in a region with an intermediate vaccination coverage. A matched case-control study was carried out in children aged 7-59 months with invasive pneumococcal disease (IPD) admitted to two university hospitals in Catalonia. Three controls matched for hospital, age, sex, date of hospitalization and underlying disease were selected for each case. Information on the vaccination status of cases and controls was obtained from the vaccination card, the child's health card, the hospital medical record or the vaccination register of the primary healthcare center where the child was attended for non-severe conditions. A conditional logistic regression analysis was made to control for the effect of possible confounding variables. The adjusted vaccination effectiveness of the complete vaccination schedule (3 doses at 2, 4 and 6 months and a fourth dose at 15 months, 2 doses at least two months apart in children aged 12-23 months or a single dose in children aged >24 months) in preventing IPD caused by vaccine serotypes was 93.7% (95% CI 51.8-99.2). It was not effective in preventing cases caused by non-vaccine serotypes. The results of this study carried out in a population with intermediate vaccination coverage confirm those of other observational studies showing high levels of effectiveness of routine 7-valent pneumococcal conjugate vaccination.

Mumps vaccine effectiveness in highly immunized populations.

The aim of the study was to investigate effectiveness of mumps MMR component in communities with high MMR coverage. Outbreak-related cases of mumps born between 1995 and 2005 notified to Navarre and Catalonia public health services during the period 2005-2007 were studied. Vaccine effectiveness (VE) and their 95%CI were calculated using the screening method. Of 47 confirmed, 85.1% immunized with at least one dose (1MMR) and 44.9% with two (2MMR). Estimated VE was 85.4% (95%CI: 67.3-93.4) for 1MMR and 88.5% (95%CI: 78.1-93.9) for 2MMR. High 2MMR coverage, improved confirmation techniques and further VE studies with all confirmed cases are needed to prevent further outbreaks.

Validity of self-reported pneumococcal vaccination status in the elderly in Spain.

The objective of this study was to evaluate the validity of information reported by the elderly on 23-valent pneumococcal polysaccharide vaccine (23vPPV) vaccination status. A cross-sectional, observational study was carried out in patients aged >or=65 years admitted to five Spanish hospitals. Data on 23vPPV vaccination history were obtained through interview of the patient or close relative and review of written medical information. The validity of the patient self-report was compared to the written medical information by calculation of the sensitivity, specificity, concordance, positive predictive value (PPV) and negative predictive value (NPV). A total of 2484 patients were initially included of whom 1814 patients (73%) responded about their vaccination status. The global sensitivity of the patient self-report was 0.74 and the specificity 0.95. The PPV was 0.92, the NPV 0.84 and the concordance 87. Vaccination cards and centralized vaccination registries in primary health care centres and hospitals should be potentiated in order to ensure that neither more nor less vaccinations are administered than are necessary.