Impact of vaccination during an epidemic of serogroup C meningococcal disease in Salvador, Brazil

To combat rising incidence of serogroup C meningococcal disease in the city of Salvador, Brazil, the Bahia state immunization program initiated routine childhood immunization with meningococcal C conjugate vaccine (MenC) in February 2010, followed by mass MenC vaccination of city residents 10-24 years of age from May through August 2010. We analyzed trends in incidence of reported cases of meningococcal disease and serogroup distribution among meningococcal isolates identified in hospital-based surveillance in Salvador from January 2000 to December 2011 and estimated vaccine effectiveness using the screening method. Annual incidence of serogroup C meningococcal disease increased from 0.1 cases per 100,000 population during 2000-2006 to 2.3 in 2009 and 4.1 in 2010, before falling to 2.0 per 100,000 in 2011. Estimated coverage of mass vaccination reached 80%, 67% and 41% among 10-14, 15-19 and 20-24 year olds, respectively. Incidence in 2011 was significantly lower than average rates in 2008-2009 among children <5 years, but reductions among 10-24 year olds were not significant. Among 10-24 year olds, a single dose of MenC vaccine was 100% effective (95% confidence interval, 79-100%) against serogroup C meningococcal disease. Low coverage in the population targeted for mass vaccination may have limited impact on ongoing transmission of serogroup C meningococcal disease despite high vaccine effectiveness.     

Dramatic decline of serogroup C meningococcal disease incidence in Catalonia (Spain) 24 months after a mass vaccination programme of children and young people

STUDY OBJECTIVES: The objective of this study was to evaluate the effectiveness of a mass vaccination programme carried out in Catalonia (Spain) in the last quarter of 1997 in response to an upsurge of serogroup C meningococcal disease (SCMD). DESIGN: Vaccination coverage in the 18 month to 19 years age group was investigated by means of a specific vaccination register. Vaccination effectiveness was calculated using the prospective cohort method. Cases of SCMD were identified on the basis of compulsory reporting and microbiological notification by hospital laboratories. Vaccination histories were investigated in all cases. Unadjusted and age adjusted vaccination effectiveness referred to the time of vaccination and the corresponding 95% confidence intervals (CI) were estimated at 6, 12, 18 and 24 months of follow up. SETTING: All population aged 18 months to 19 years of Catalonia. MAIN RESULTS: A total of seven cases of SCMD were detected at six months of follow up (one in the vaccinated cohort), 12 cases at 12 months (one in the vaccinated cohort), 19 cases at 18 months (two in the vaccinated cohort) and 24 at 24 months (two in the vaccinated cohort). The age adjusted effectiveness was 84% (95%CI 30, 97) at six months, 92% (95%CI 63, 98) at 12 months, 92% (95% CI 71, 98) at 18 months and 94% (95%CI 78, 98) at 24 months. In the target population, cases have been reduced by more than two thirds (68%) two years after the vaccination programme. In the total population the reduction was 43%. CONCLUSION: Vaccination effectiveness has been high in Catalonia, with a dramatic reduction in disease incidence in the vaccinated cohort accompanied by a relevant reduction in the overall population. Given that vaccination coverage was only 54.6%, it may be supposed that this vaccination effectiveness is attributable, in part, to the herd immunity conferred by the vaccine.     

Impact and effectiveness of meningococcal C conjugate vaccine following its introduction in Spain

This study describes the epidemiological impact of meningococcal C conjugate vaccine on age groups targeted by this vaccination programme in Spain, and estimates high short-term vaccine effectiveness values under field conditions in the 4 years following its introduction. Meningococcal C conjugate vaccine has led to a substantial reduction in incidence of meningococcal serogroup C disease in Spain among age groups targeted for intervention nationwide. Disease surveillance in the 4 years since the vaccine was introduced has enabled vaccine effectiveness (VE) to be estimated. The vaccine registered high short-term VE values but there has been some loss of VE with time. Four years after vaccination, vaccine protection levels exceeded 94% in cohorts immunised during the campaign. Among children vaccinated in routine childhood immunisation programmes, however, long-term VE loss was greater. Accordingly, there is a need for ongoing re-evaluation of VE and ascertainment of long-term vaccine protection. The findings reported would allow to decide on the advisability of revising current vaccination guidelines.     

The effectiveness of serogroup C meningococcal vaccine estimated from routine surveillance data

Serogroup C meningococcal vaccine effectiveness was estimated from routine surveillance data, based on a comparison of the proportion of vaccine and non-vaccine serogroups in vaccinated and unvaccinated reported cases. Between 1 April 1993 and 31 March 1998, 109 eligible cases were reported. Among the 54 cases caused by serogroup C, 38 had been vaccinated. Among the 55 cases caused by non-vaccine serogroups, 49 had been vaccinated. Vaccine effectiveness was estimated at 71% (95% CI: 21-89%), a value similar to that obtained in the same population by a cohort study. Effectiveness was lower in children immunized before the age of 10. This demonstrates that meningococcal vaccine effectiveness can be estimated from information obtained routinely from cases only, as an alternative to the more expensive cohort or case-control designs.     

Meningococcal C conjugate vaccine effectiveness before and during an outbreak of invasive meningococcal disease due to Neisseria meningitidis serogroup C/cc11, Tuscany,Italy

IntroductionIn Tuscany, Italy, where a universal immunization program with monovalent meningococcal C conjugate vaccine (MCC) was introduced in 2005, an outbreak of invasive meningococcal disease (IMD) due to the hypervirulent strain of Neisseria meningitidis C/cc11 occurred in 2015–2016, leading to an immunization reactive campaign using either the tetravalent (ACWY) meningococcal conjugate or the MCC vaccine. During the outbreak, IMD serogroup C (MenC) cases were also reported among vaccinated individuals. This study aimed to characterize meningococcal C conjugate vaccines (MenC-vaccines) failures and to estimate their effectiveness since the introduction (2005–2016) and during the outbreak (2015–2016).MethodsMenC cases and related vaccine-failures were drawn from the National Surveillance System of Invasive Bacterial Disease (IBD) for the period 2006–2016. A retrospective cohort-study, including the Tuscany' population of the birth-cohorts 1994–2014, was carried out. Based on annual reports of vaccination, person-years of MenC-vaccines exposed and unexposed individuals were calculated by calendar-year, birth-cohort, and local health unit. Adjusted (by birth-cohort, local health unit, and calendar-year) risk-ratios (ARR) of MenC invasive disease for vaccinated vs unvaccinated were estimated by the Poisson model. Vaccine-effectiveness (VE) was estimated as: VE = 1-ARR.ResultsIn the period 2006–2016, 85 MenC-invasive disease cases were reported; 61 (71.8%) from 2015 to 2016. Twelve vaccine failures occurred, all of them during the outbreak. The time-interval from immunization to IMD onset was 20 days in one case, from 9 months to 3 years in six cases, and ≥7 years in five cases. VE was, 100% (95%CI not estimable, p = 0.03) before the outbreak (2006–2014) and 77% (95%CI 36–92, p < 0.01) during the outbreak; VE was 80% (95%CI 54–92, p < 0.01) during the overall period.ConclusionsIn Tuscany, MenC-vaccine failures occurred exclusively during the 2015–2016 outbreak. Most of them occurred several years after vaccination. VE during the outbreak-period was rather high supporting an effective protection induced by MenC-vaccines.     

Effectiveness of a vaccination programme for an epidemic of meningococcal B in New Zealand

New Zealand has experienced a prolonged epidemic of meningococcal B disease since 1991. The epidemic has waned significantly since its most recent peak in 2001. A strain-specific vaccine, MeNZB, was introduced to control the epidemic in 2004, achieving 81% coverage of people under the age of 20. The vaccine was rolled out in a staged manner allowing the comparison of disease rates in vaccinated and unvaccinated individuals in each year.Vaccine effectiveness in people aged under 20 years is estimated using a Poisson regression model in the years 2001-2008, including adjustments for year, season, age, ethnicity, region and socioeconomic status. Further analyses investigate the dose response relationship, waning of the vaccine effect after one year, and cross-protection against other strains of meningococcal disease.The primary analysis estimates MeNZB vaccine effectiveness to be 77% (95% CI 62-85) after 3 doses and a mean follow-up time of 3.2 years. There is evidence for a protective effect after 2 doses 47% (95% CI 16-67), and no evidence for a waning of effectiveness after one year. Simultaneous modelling of invasive pneumococcal disease and epidemic strain meningococcal B suggests a degree of residual confounding that reduces the effectiveness estimate to 68%. There is evidence for some cross-protection of MeNZB against non-epidemic strains.The MeNZB vaccine was effective against the New Zealand epidemic strain of meningococcal B disease. Between July 2004 and December 2008 an estimated 210 epidemic strain cases (95% CI 100-380), six deaths and 15-30 cases of severe sequelae were avoided in New Zealand due to the introduction of the MeNZB vaccine.     

Evolution of meningococcal disease in the community of Madrid. Effectiveness of antimeningococcal A+C vaccination

BACKGROUND: In 1997 (between 22 September and 14 November) an A + C meningococcal mass vaccination campaign was carried out in Madrid, targeting the age group of from 18 months to 19 years of age, in the face of an increase in the number of cases of meningococcal disease caused by serogroup C occurring in the 1996-97 season. This study forms a part of the impact assessment of that campaign. METHODS: The evolution of the meningococcal disease, by means of the comparison of rates of incidence; and the efficacy of the vaccination campaign was determined after one year (1997-98 season) and after two years (1997-98 and 1998-99 seasons) of monitoring. The vaccine efficacy has been calculated as [1-(Incidence rate in vaccinated/Incidence rate in unvaccinated)]* 100. RESULTS: A significant drop was registered in the incidence of serogroup C meningococcal disease on comparing the 1997-98 and 1998-99 seasons with the epidemic season (1996-97). The vaccine efficacy after two years of monitoring subsequent to the vaccination campaign was 76.9% for the global population between 18 months and 19 years of age and 88.5% in the group of vaccinated individuals between 15 and 19 years of age. CONCLUSIONS: The vaccine efficacy obtained is compatible with that described in the relevant literature. The significant reduction in the incidence of meningococcal disease caused by serogroup C was due to the vaccine efficacy obtained.     

Assessing the effectiveness of vaccination programs

Vaccines have contributed enormously to reducing the incidence of many communicable diseases. The protective efficacy of a vaccine refers to the health effects of the vaccine applied in optimal, ideal conditions, whereas the effectiveness of a vaccination program refers to the health effects of vaccination in the vaccinated individuals in clinical practice or within public health programs, which may differ widely from optimal conditions. Vaccine efficacy is estimated by randomized clinical trials. In contrast, effectiveness can be measured by various types of epidemiological studies: randomized community trials, in which the target vaccine is randomly assigned to a group and disease incidence in this group is compared with that of an unvaccinated group; cohort studies, which are observational epidemiological studies in which the vaccination status is known in healthy vaccinated (vaccinated cohort) and unvaccinated (unvaccinated cohort) people and the occurrence of the disease in the two groups is studied; and observational case-control studies, in which two groups are selected; one with the disease under investigation (cases) and the other without (controls), and vaccination histories are investigated in the two groups. Vaccine effectiveness may also be estimated by comparing attack rates in epidemic outbreaks or secondary attack rates in the home, or by screening.     

Influenza outbreaks in nursing homes: how effective is influenza vaccine in the institutionalized elderly?

During the 1984-1985 influenza season, outbreaks of influenza A (H3N2) occurred in three Connecticut nursing homes. Influenza vaccination rates were 67% (96 out of 144), 35% (30 out of 85) and 69% (332 out of 483), respectively. The relative risk of illness for vaccinated compared to unvaccinated residents was 1.8 (95% confidence interval, 0.6, 5.9), 1.6 (95% confidence interval, 0.8, 3.0) and 1.1 (95% confidence interval, 0.8, 1.7) for each of the three nursing homes, respectively. In the third outbreak, 22 vaccinated residents without clinical illness had a geometric mean titer of hemagglutination-inhibition (HI) antibody of 20. Although low, this titer was significantly higher than that of nine unvaccinated residents without clinical illness (12, p less than .05); only three (14%) vaccinated residents had HI titers of greater than or equal to 40. These results suggest that levels of HI antibody in vaccinated residents were not protective at the time of the third outbreak, four to five months after vaccination. In general, the study of vaccine effectiveness in nursing homes is limited by sample size and statistical power. Despite these limits, the retrospective investigation of influenza outbreaks in nursing homes is often the only practical way to evaluate influenza vaccine effectiveness in the elderly on a yearly basis.     

Effectiveness of pneumococcal vaccination in older adults with chronic respiratory diseases: results of the EVAN-65 study

A prospective cohort study evaluating the clinical effectiveness of the 23-valent pneumococcal polysaccharide vaccine was conducted among 1298 Spanish older adults with chronic respiratory diseases (bronchitis, emphysema or asthma) who were followed between 2002 and 2005. Main outcomes were all-cause community-acquired pneumonia (CAP) and 30 days mortality from CAP. The association between vaccination and the risk of each outcome was evaluated by multivariable Cox proportional-hazard models adjusted for age and comorbidity pneumococcal vaccination did not alter significantly the risk of overall CAP (hazard ratio [HR]: 0.77; 95% confidence interval [CI]: 0.56-1.07) and 30 days mortality from CAP (HR: 0.87; 95% CI: 0.33-2.28). However, a borderline significant reduction of 30% in the risk of all-cause hospitalisation for CAP was observed among vaccinated subjects (HR: 0.70; 95% CI: 0.48-1.00; p=0.052). The effectiveness of the vaccine on the combined endpoint of pneumococcal and unknown organism infections reached 34% (HR: 0.66; 95% CI: 0.43-1.01; p=0.059). Although our findings suggest moderate benefits from the vaccination, the evidence of clinical effectiveness appears limited.     

Deaths averted by influenza vaccination in the U.S. during the seasons 2005/06 through 2013/14

BackgroundExcess mortality due to seasonal influenza is substantial, yet quantitative estimates of the benefit of annual vaccination programs on influenza-associated mortality are lacking.MethodsWe estimated the numbers of deaths averted by vaccination in four age groups (0.5 to 4, 5 to 19, 20 to 64 and ≥65 yrs.) for the nine influenza seasons from 2005/6 through 2013/14. These estimates were obtained using a Monte Carlo approach applied to weekly U.S. age group-specific estimates of influenza-associated excess mortality, monthly vaccination coverage estimates and summary seasonal influenza vaccine effectiveness estimates to obtain estimates of the number of deaths averted by vaccination. The estimates are conservative as they do not include indirect vaccination effects.ResultsFrom August, 2005 through June, 2014, we estimated that 40,127 (95% confidence interval [CI] 25,694 to 59,210) deaths were averted by influenza vaccination. We found that of all studied seasons the most deaths were averted by influenza vaccination during the 2012/13 season (9398; 95% CI 2,386 to 19,897) and the fewest during the 2009/10 pandemic (222; 95% CI 79 to 347). Of all influenza-associated deaths averted, 88.9% (95% CI 83 to 92.5%) were in people ≥65 yrs. old.ConclusionsThe estimated number of deaths averted by the US annual influenza vaccination program is considerable, especially among elderly adults and even when vaccine effectiveness is modest, such as in the 2012/13 season. As indirect effects (“herd immunity”) of vaccination are ignored, these estimates represent lower bound estimates and are thus conservative given valid excess mortality estimates     

Recommendations for the use of Taylor series confidence intervals for estimates of vaccine efficacy

A simple formula for calculating confidence intervals by means of a Taylor series variance approximation has been recommended for gauging the precision of estimates of vaccine efficacy. To evaluate the performance of Taylor series 95% confidence intervals for vaccine efficacy, we conducted a simulation study for commonly expected values of vaccine efficacy, risk of disease in the unvaccinated population, and sample sizes of the vaccinated and unvaccinated groups. In the first simulation, the sample size in the vaccinated group was 500 or 1000, whereas that in the unvaccinated group ranged from 10 to 1000. The confidence intervals were accurate when the sample size in the unvaccinated group was ≥50 and the risk of disease was 0.3-0.9. In contrast, the intervals were too narrow when all three of the following situations occurred: the number of unvaccinated was small (10 or 20), the true vaccine efficacy was relatively low (60% or 80%), and the risk of disease was 0.5-0.9. Furthermore, when the true vaccine efficacy was high (90% or 95%) and the disease risk in the unvaccinated was low (0.1 and 0.2), the confidence intervals were too broad, especially when the unvaccinated sample size was <50. Additional simulations with a sample size in the vaccinated group of 200 gave broad intervals for 95% vaccine efficacy (for all values of disease risk) and for 90% vaccine efficacy when the disease risk was ≤0.3.     

Influenza vaccination in paediatric nurses: cross-sectional study of coverage, refusal, and factors in acceptance

BACKGROUND: Influenza vaccination among health-care workers is poor, and the effectiveness of hospital vaccination programs remains unclear. Little is known about the effectiveness of intensive evidence-based vaccination programs in nursing staff. We determined whether the recommended vaccination rate could be achieved among paediatric nurses during an intensive promotional program for influenza vaccination. We also sought to identify the reasons for which nurses refuse the influenza vaccine and predictors of future vaccination intent. METHODS: We offered influenza vaccination to nursing staff during an influenza season through a multi-component program that included intensive promotional activities. We analysed vaccination data to determine uptake rates. In a cross-sectional survey, self-administered questionnaires were distributed to all nurses with patient contact during that season. The questionnaire evaluated their vaccine use, site of work, absenteeism and physician visits due to respiratory illness, vaccination intent for the subsequent influenza season, and other items. We surveyed vaccinated nurses regarding their program experiences and the frequency and severity of adverse reactions. Unvaccinated nurses were asked their reasons for refusing vaccination. Multiple logistic-regression analysis was conducted to identify variables that predicted the likelihood of future vaccine acceptance. RESULTS: More than 75% (895/1,182) of applicable nurses were vaccinated in the program. The questionnaire response rate was nearly 48% (585/1,230). Vaccination in the program during the current season (odds ratio [OR] 101.99, 95% confidence interval [CI] 52.54-197.98), program convenience (OR 199.19, 95% CI 98.01-404.11), and a physician visit for respiratory illness (OR 2.44, 95% CI 1.29-4.61) were found to be independent predictors of intent to receive the vaccine the following season. A lack of perceived personal need was the most common reason for vaccine refusal, given in 30% (77/258) of unvaccinated respondents. CONCLUSIONS: Adequate coverage of nurses is achievable during an intensive voluntary immunisation program against influenza, using best-known practices. Perceived lack of personal benefit is a major deterrent, while program convenience and previous vaccination strongly predict future vaccine acceptance. Our findings support interventions that improve the convenience of hospital immunisation programs for influenza, particularly those that are aimed at nurses and that promote vaccine efficacy and benefits.     

Clinical effectiveness of 13-valent and 23-valent pneumococcal vaccination in middle-aged and older adults: The EPIVAC cohort study, 2015–2016

BackgroundClinical benefits using the 23-valent pneumococcal polysaccharide vaccine (PPsV23) or the 13-valent pneumococcal conjugate vaccine (PCV13) in adults are controversial. This study investigated clinical effectiveness for both PPsV23 and PCV13 in preventing pneumonia among middle-aged and older adults.MethodsPopulation-based cohort study involving 2,025,730 persons ≥50 years in Catalonia, Spain, who were prospectively followed between 01/01/2015 and 31/12/2016. Primary outcomes were hospitalisation from pneumococcal or all-cause pneumonia and main explanatory variable was PCV13/PPsV23 vaccination status. Multivariable Cox regression models were used to estimate vaccination effectiveness adjusted for age and baseline-risk conditions.ResultsCohort members were followed for 3,897,151 person-years (17,496 PCV13 vaccinated and 1,551,502 PPsV23 vaccinated), observing 3259 pneumococcal pneumonias (63 in PCV13 vaccinated, 2243 in PPsV23 vaccinated) and 24,079 all-cause pneumonias (566 in PCV13 vaccinated, 17,508 in PPsV23 vaccinated). Global incidence rates (per 100,000 person-years) were 83.6 for pneumococcal pneumonia (360.1 in PCV13 vaccinated, 144.6 in PPsV23 vaccinated) and 617.9 for all-cause pneumonia (3235.0 in PCV13 vaccinated, 1128.5 in PPsV23 vaccinated). In the multivariable analyses, the PCV13 appeared significantly associated with an increased risk of pneumococcal pneumonia (hazard ratio [HR]: 1.52; 95% confidence interval [CI]: 1.17–1.97; p = 0.002) and all-cause pneumonia (HR: 1.76; 95% CI: 1.61–1.92; p < 0.001) whereas the PPsV23 did not alter the risk of pneumococcal pneumonia (HR: 1.08; 95% CI: 0.98–1.19; p = 0.132) and slightly increased the risk of all-cause pneumonia (HR: 1.17; 95% CI: 1.13–1.21; p < 0.001). In stratified analyses focused on specific target population subgroups (i.e., elderly people, at-risk and high-risk individuals), protective effects of vaccination did not emerge either.ConclusionData does not support clinical benefits from pneumococcal vaccination (nor PCV13 neither PPsV23) against pneumonia among Catalonian adults in the current era of universal PCV’s childhood immunisation.     

Evaluación de la efectividad de los programas de vacunación

Vaccines have contributed enormously to reducing the incidence of many communicable diseases. The protective efficacy of a vaccine refers to the health effects of the vaccine applied in optimal, ideal conditions, whereas the effectiveness of a vaccination program refers to the health effects of vaccination in the vaccinated individuals in clinical practice or within public health programs, which may differ widely from optimal conditions. Vaccine efficacy is estimated by randomized clinical trials. In contrast, effectiveness can be measured by various types of epidemiological studies: randomized community trials, in which the target vaccine is randomly assigned to a group and disease incidence in this group is compared with that of an unvaccinated group; cohort studies, which are observational epidemiological studies in which the vaccination status is known in healthy vaccinated (vaccinated cohort) and unvaccinated (unvaccinated cohort) people and the occurrence of the disease in the two groups is studied; and observational case-control studies, in which two groups are selected; one with the disease under investigation (cases) and the other without (controls), and vaccination histories are investigated in the two groups. Vaccine effectiveness may also be estimated by comparing attack rates in epidemic outbreaks or secondary attack rates in the home, or by screening.     

Estimation of the time-dependent vaccine efficacy from a measles epidemic

We present a method to estimate the time-dependent vaccine efficacy from the cohort-specific vaccination coverage and from data on the vaccination status of cases and apply it to a measles epidemic in Germany which involved 529 cases, 88 of whom were vaccinated and 370 unvaccinated (for the remaining 71 cases the vaccination status is unknown). Our epidemiological model takes into account that maternal antibodies prevent successful vaccination and that vaccine immunity may be lost over time. Model parameters are estimated from the data using maximum likelihood. Vaccination coverage, as determined in school surveys, ranged from 27.6 per cent for the cohort born in 1974 to 85 per cent for the 1986 cohort, which is far too low to prevent measles transmission. Cohorts for which no school surveys were performed are omitted from analysis. Thus, sufficient data are available for only 282 cases, 69 of whom are vaccinated. According to our estimates, measles vaccinations provided no immunity before 1978 (95 per cent CI: 0 to 47 percent), for the period 1978-1982, the estimated vaccine efficacy was 80 percent (95 percent CI: 67 to 89 percent), and for 1982-1990 it was 97 percent (95 percent CI: 93 to 99 percent). After 1990, the estimated value dropped to 89 per cent, but its confidence interval widely overlaps with that of the previous period (95 percent CI: 74 to 97 percent). Loss of immunity was estimated to be zero (95 percent CI: 0 to 0.003/year). Several sensitivity analyses were performed with respect to the model assumptions. A modified model which assumed constant efficacy at all vaccination times yielded a high estimate of 96 per cent (95 percent CI: 92 to 98 percent) for primary vaccine efficacy but also a high loss rate of immunity of 0.007/year (95 percent CI: 0.001 to 0.012) to explain the high fraction of vaccinated cases among older individuals. The likelihood score value is however significantly inferior compared to the score value of the model with time-dependent vaccine efficacy.     

Impact of systematic vaccination with the antimeningococcal C conjugated vaccine in a health area in Andalusia

BACKGROUND: A retrospective longitudinal study of population incidence was made to assess the effectiveness of meningococcal serogroup C conjugate vaccine, after its mass introduction in children in the geographic area of a health district, measuring its population impact, and we have studied the state of the meningococcal disease. METHODS: Vaccine coverage in children born between 1991 and 2001, and rates of incidence in declared cases of meningococcal disease in seven epidemiological seasons (1997/98 to 2003/04) were calculated. The impact of vaccination against serogroup C meningitis was assessed comparing the average annual rates of previous and later seasons to the vaccination campaigns in population younger and older than 10, using the Fisher exact test. RESULTS: In all the study period, 109 cases of meningococcal disease were declared, of which 50 were of serogroup C meningococcal disease. Starting from 2000/2001 season the incidence of serogroup C disease decreased in the population below 10. In this age group, the annual average rate of post-vaccine seasons decreases in respect to pre-vaccine (from 8.2 to 2.0 per 100,000 inhabitants) showing a statistically significant difference. In the population above 10 years, this incidence reduction was not observed. In the study period, no case of vaccine failure was declared. CONCLUSIONS: The absence of vaccine failure and the impact observed on the incidence of serogroup C meningococcal disease in children under 10 suggests the effectiveness of this new conjugate vaccine, together with suitable vaccination conditions (vaccination schedule, high catch-up, etc.) which are developing in our health district.     

School-Located Vaccination of Adolescents With Insurance Billing: Cost,Reimbursement, and Vaccination Outcomes

PurposeTo assess, in a school-located adolescent vaccination program that billed health insurance, the program costs, the proportion of costs reimbursed, and the likelihood of vaccination.MethodsDuring the 2010–2011 school year, vaccination clinics were held for sixth- to eighth-grade students at seven Denver public schools. Vaccine administration and purchase costs were compared with reimbursement by insurers. Multivariate analyses were used to compare the likelihood of vaccination among students in intervention schools with students in control schools who did not participate in the program, with analyses stratified by grade (sixth grade vs. seventh–eighth grades).ResultsFifteen percent (466 of 3,144) of students attending intervention schools were vaccinated at school-located vaccination clinics. Among students vaccinated at school, 41% were uninsured, 37% publicly insured, and 22% privately insured. Estimated vaccine administration costs were $23.98 per vaccine dose. Seventy-eight percent of vaccine purchase costs and 14% of vaccine administration costs were reimbursed by insurers; 41% of total program costs were reimbursed. Sixth-grade students in intervention schools were more likely than those in control schools to receive tetanus–diphtheria–acellular pertussis (risk ratio [RR], 1.30; 95% confidence interval [CI], 1.08, 1.57), meningococcal conjugate (RR, 1.42; CI, 1.18, 1.70), and human papillomavirus (for females only, RR, 1.69; CI, 1.21, 2.36) vaccines during the 2010–2011 school year, with similar results for seventh- to eighth-grade students.ConclusionsAlthough school-located adolescent vaccination with billing appears feasible and likely to improve vaccination rates, improvements in insurance coverage and reimbursement rates may be needed for the long-term financial sustainability of such programs.     

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

IntroductionAlthough 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.MethodsCases 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.ResultsFrom 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).ConclusionsAfter 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.     

Effectiveness of the current and prior influenza vaccinations in Northern Spain, 2018–2019

BackgroundThe population targeted for influenza vaccination can be repeatedly vaccinated over successive seasons, and vaccines received in previous seasons may retain preventive effect. This study aims to estimate the effectiveness of inactivated influenza vaccines received in the current and prior seasons in the 2018–2019 season.MethodsInfluenza-like illness patients attended by sentinel general practitioners or admitted to hospitals in Navarre, Spain, were tested for influenza. Vaccination status in the current and three prior seasons was obtained from the vaccination registry. The test-negative design was used to estimate the vaccine effectiveness.ResultsA total of 381 influenza A(H1N1)pdm09 cases, 341 A(H3N2) cases and 1222 controls were analysed. As compared to individuals unvaccinated in the current and three prior seasons, the influenza vaccine effectiveness against A(H1N1)pdm09 was 57% (95% confidence interval [CI]: 40%, 70%) for current season vaccination regardless of prior doses and 48% (95%CI: 14%, 68%) for vaccination in prior seasons but not in the current season. These estimates were 12% (95%CI: −23%, 37%) and 27% (95%CI: −22%, 56%), respectively, against influenza A(H3N2). Individuals vaccinated with the two A(H1N1)pdm09 strains in influenza vaccines since 2009, A/Michigan/45/2015 and A/California/07/2009, had higher protection (68%; 95%CI: 53%, 77%) than those vaccinated with A/Michigan/45/2015 only (29%, p = 0.020) or with A/California/07/2009 only (34%, p = 0.005).ConclusionThese results suggest moderate effectiveness of influenza vaccination against A(H1N1)pdm09 and low effectiveness against A(H3N2) influenza in the 2018–2019 season. Vaccination in prior seasons maintained a notable protective effect. Strains included in previous vaccines were as effective as the current vaccine strain, and both added their effects against influenza A(H1N1)pdm09.