Effectiveness of acellular pertussis vaccine and evolution of pertussis incidence in the community of Madrid from 1998 to 2015.

INTRODUCTION: Pertussis is a communicable disease that primarily affects infants. Vaccination has led to an important reduction in the incidence of the disease, however, resurgence of the disease has been observed. This study aimed to analyze the incidence of pertussis and assess the vaccination effectiveness (VE) of different schedules of acellular pertussis vaccination in the community of Madrid. METHODS: Pertussis cases notified to the Mandatory Disease Reporting System from 1998 to 2015 were analyzed. Five comparison periods were created: 1998-2001 (reference), 2002-2005, 2006-2009, 2010-2012 and 2013-2015. The incidence ratio (IR) between inter-epidemic periods was analyzed using a Poisson regression. VE was calculated using the screening method. Vaccine status data were collected from the vaccine registry. RESULTS: In total, 3855 cases were notified. Inter-epidemic periods were observed every 3-4 years. The incidence increased (IR: 5.99, p < 0.05) in the 2013-2015 period, particularly among infants younger than 1 month (IR: 32.41, p < 0.05). Vaccination data were available in 89% of cases. For those receiving the last dose at ≤6-month VE was 89.9% (95% confidence interval (CI): 87.3-92.0) after one year of follow-up, and 85.5% (95% CI: 82.4-88.1) after 11 years of follow-up. For those receiving the last dose at 18-months VE decreased from 98.8% (95% CI: 98.3-99.1) to 85.1% (95% CI: 81.9-87.7) in the same period, and for those receiving the last dose at 4-year VE decreased from 99.6% (95% CI: 99.3-99.7) to 79.3% (95% CI: 74.6-83.1). CONCLUSIONS: B. pertussis is circulating in our population, as shown by the epidemic peaks and increased incidence of pertussis in recent years. VE increased with the number of doses and decreased with the follow-up period. The effect of this and other vaccination strategies must be monitored to control the disease.

Erratum to: Changes in the pneumococcal disease-related hospitalisations in Spain after the replacement of 7-valent by 13-valent conjugate vaccine.

The original version of this article was published online with an incorrectly arranged Table 2. Also, Figs. 1 and 2 were missing the legends.

Effectiveness of different vaccine schedules for heptavalent and 13-valent conjugate vaccines against pneumococcal disease in the Community of Madrid.

INTRODUCTION: The heptavalent pneumococcal conjugate vaccine (PCV-7) was added to the childhood routine vaccination program in the Community of Madrid in November of 2006 with 3+1 recommended doses and a catch-up for those under 2years old. In June 2010, PCV-7 was replaced by 13-valent vaccine (PCV-13) with 2+1 recommended doses. In July of 2012, the PCV-13 was removed from the funded program and reintroduced again (2+1 recommended doses) in December 2014. In between, children were vaccinated privately with 3+1 recommended doses of PCV-13. The aim of this study was to evaluate the effectiveness of each vaccination schedule used in the Community of Madrid. METHODS: We included all cases of invasive pneumococcal disease (IPD) reported between 2007 and 2015 to the Notifiable Diseases Surveillance System. Vaccination information was obtained from the Immunization Registry. Vaccine effectiveness (VE) was estimated using the indirect cohort design for cases with serotype information. RESULTS: A total 779 cases were included in the study. Among them 47.6% of the cases were primo-vaccinated with booster, 20% primo-vaccinated, 15.9% incompletely primo-vaccinated and 16.5% not vaccinated. The VE for ≥1 doses of any PCV was 82% (CI 95%: 67.8-89.9%): 91.9% (CI 95%: 76.5-97.2%) for PCV-7 and 77.2% (48.6-89.9%) for PCV-13. VE in those receiving the full 2+1 or 3+1 schedules was 100% for both vaccines. CONCLUSIONS: A high number of vaccine failures were reported in children before they had the opportunity to receive the booster dose, especially due to PCV-13-non-PCV-7 serotypes. VE was higher for PCV-7 compared to PCV-13, except for those that received the complete schedule with booster that achieved 100% of VE, which shows the relevance of the vaccines and complying with all doses scheduled.

Changes in the pneumococcal disease-related hospitalisations in Spain after the replacement of 7-valent by 13-valent conjugate vaccine.

In Spain, anti-pneumococcal vaccination is recommended for all children under 2 years old, high-risk groups and adults ≥65 years old. However, it is not funded in most autonomous communities. This study aims to compare pneumococcal disease hospitalisation rates between Period 1 (2007-2009), when 7-valent (PCV7) vaccine was available, and Period 2 (2011-2013), after the change to 13-valent (PCV13) vaccine in Spain. Data on hospitalisations were obtained from the National Registry of Hospitalisations. We calculated hospitalisation rates (HRs) and hospitalisation rate ratios (HRRs) among periods by age group and autonomous community, for all and by clinical presentation. From 138,361 patients hospitalised, 83,528 (60.4 %) were males. The median age was 73.8 years. The most common clinical presentation was pneumonia (133,204 hospitalisations; 96.3 %), followed by septicaemia (7053 hospitalisations; 5.1 %) and meningitis (3182 hospitalisations; 2.3 %). In Period 2, hospitalisations among children <5 years old decreased for pneumonia [HRR: 0.37; 95 % confidence interval (95 % CI): 0.35 to 0.39] and meningitis (HRR: 0.53; 95 % CI: 0.44 to 0.65). For adults ≥65 years old, pneumonia (HRR: 0.49; 95 % CI: 0.49 to 0.50) and peritonitis (HRR: 0.34; 95 % CI: 0.19 to 0.63) hospitalisations decreased and septicaemia hospitalisations (HRR: 1.27; 95 % CI: 1.18 to 1.36) increased. Significant changes in HRs for pneumococcal disease were observed even without an integrated and continuous vaccination programme after the introduction of PCV13, especially in children <5 years old and for pneumonia. The impact of the PCV13 adult vaccination new recommendations on the septicaemia increase reported should be evaluated in the future.

Meningococcal C conjugate age-dependant long-term loss of effectiveness.

INTRODUCTION: Although different epidemiological studies have assessed meningococcal C conjugate vaccine effectiveness within 1 and >1 year since vaccination, none of them evaluated long-term effectiveness. In order to assess if epidemiological data correlates with the findings described in seroprevalence studies we evaluated long-term vaccine effectiveness over time, up to 10 years since vaccination. METHODS: Cases targeted by vaccination programs and notified to the Spanish Surveillance System between 2001 and 2013 were included in the study. Vaccine effectiveness was estimated using the screening method. Relationship between vaccine effectiveness and time since vaccination was explored using point estimates, simple logistic regression or restricted cubic splines logistic regression model for all and for those vaccinated at <1, 1-11 and at 12-19 years of age. RESULTS: From 345 confirmed cases reported in the period and targeted by vaccination programs, 125 (36.23%) were vaccine failures. Proportion of vaccine failures decreased with age of vaccination: 63.97% at <1 year; 36.84% at 1-11 years; and 3.88% at 12-19 years. Using the best model for each group, vaccine effectiveness decreased from 99.12% to 90.85% (%change=-8.3%) for all; from 99.04% to 48.60% (%change=-50.9%) for those vaccinated at <1 years and from 99.45% to 90.18% (%change=-9.3%) for those vaccinated at 1-11 years after 10 years since vaccination. For those vaccinated at 12-19 years no changes were observed in vaccine effectiveness after 10 years (p=0.968). CONCLUSIONS: After 10 years, vaccine effectiveness decreased by 50% in those vaccinated at <1 year, while those vaccinated with one dose at 12-19 years showed no changes. Vaccine failures occurred early after vaccination and more frequently in those vaccinated at younger ages. Vaccination at ≥12 years seems to be related to a low number of vaccine failures and a higher and endurable protection over time.

Increase of pertussis incidence in 2010 to 2012 after 12 years of low circulation in Spain.

In Spain, whole cell pertussis vaccination started in 1975, with three doses before the age of 6-7 months. Doses at 15-18 months and 4-6 years were introduced in 1996 and 2001, respectively. Spain switched to an acellular vaccine in 2005. From 1998 to 2009, pertussis incidence rates remained ≤1.5 cases/100,000 inhabitants but increased from 2010 to 7.5 cases/100,000 in 2012. Data from 1998 to 2012 were analysed to assess disease trends and susceptible populations. We defined four epidemic periods: 1998-2001 (reference), 2002-05, 2006-09 and 2010-12. In 2002-05, the incidence rate increased in individuals aged 15-49 years (IRR: 1.41 (95% CI: 1.11-1.78)) and ≥50 years (IRR: 2.78 (95% CI: 1.78-4.33)) and in 2006-09 increased also in infants aged <3 months (IRR: 1.83 (95% CI: 1.60-2.09)). In 2010-12, the incidence rate increased notably in all age groups, with IRRs ranging between 2.5 (95% CI: 2.3-2.8) in 5-9 year-olds and 36.0 (95% CI: 19.4-66.8) in 20-29 year-olds. These results, consistent with the country's vaccination history, suggest a progressive accumulation of susceptible individuals due to waning immunity after years of low incidence. Further vaccination strategies should be assessed and implemented to prevent pertussis in pre-vaccinated infants, in whom the disease is more severe.

Changes in meningococcal C epidemiology and vaccine effectiveness after vaccine introduction and schedule modification.

PURPOSE: Meningococcal C conjugate vaccine was included in December 2000 in the Spanish childhood vaccination at 2, 4 and 6 months of age. In 2006, routine vaccination was modified to two doses at 2 and 4-6 months and a booster dose during the second year of age. Additionally, successive catch-up campaigns were launched to extend protection to older groups. This study provides long-term information about the vaccine effectiveness (VE) and the impact of vaccination in meningococcal C disease epidemiology in Spain. METHODS: We assessed surveillance data from season 1996/97 to season 2012/13 to describe changes in incidence and lethality of the disease. The vaccine-effectiveness study covered all cases notified from January 1st of 2001 onwards and evaluated vaccine effectiveness in both routines and in catch-up campaigns. To investigate the decline in protection over time, we compared the vaccine effectiveness within 1 year and more than one year since vaccination. RESULTS: The incidence of meningococcal serogroup C disease decreased first in those age-groups targeted for vaccination. But after 2006/07 season the decrease in incidence was generalised. Vaccine effectiveness was high in all vaccination programmes, although 2, 4-6 months (+ booster dose) routine showed higher overall vaccine effectiveness than 2, 4 and 6 months routine (99.3% vs. 90.2%). VE >1 year since vaccination was lower in 2, 4 and 6 months compared to 2 and 4-6 months (+ booster) routine (81.4% vs. 89.1%). For catch-up campaigns, VE increased and loss of VE decreased with the age of administration. Overall VE was 94.83 (CI95%: 93.37, 95.97), 98.82 (CI95%: 97.96, 99.31) and 90.89 (CI95%: 87.79, 93.21) for ≤ 1 and >1 year since vaccination, respectively. CONCLUSIONS: The meningococcal C conjugate vaccination programme has been extremely successful in controlling the disease and continues to be evaluated and adapted to the changes in the epidemiology of the disease to ensure long-term vaccine protection.