Evaluation of invalid vaccine doses

Multilevel Implementation Strategies for Adolescent Human Papillomavirus Vaccine Uptake: A Cluster Randomized Clinical Trial

Importance

Despite availability of a safe and effective vaccine, an estimated 36 500 new cancers in the US result from human papillomavirus (HPV) annually. HPV vaccine uptake falls short of national public health goals and lags other adolescent vaccines.

Objective

To evaluate the individual and combined impact of 2 evidence-based interventions on HPV vaccination rates among 11- and 12-year-old children.

Design, Setting, and Participants

The study team conducted a cluster randomized clinical trial with a stepped-wedge factorial design at 6 primary care practices affiliated with Mayo Clinic in southeastern Minnesota. Using block randomization to ensure balance of patient volumes across interventions, each practice was allocated to a sequence of four 12-month steps with the initial baseline step followed by 2 intermediate steps (none, 1, or both interventions) and a final step wherein all practices implemented both interventions. Each month, all eligible children who turned 11 or 12 years in the 2 months prior were identified and followed until the end of the step. Data were analyzed from April 2018 through March 2019. Participants included children who turned 11 or 12 years old and were due for a dose of the HPV vaccine.

Interventions

Parents of eligible patients were mailed reminder/recalls following their child's birthdays. Health care professionals received confidential audit/feedback on their personal in-office success with HPV vaccine uptake via intra-campus mail. These 2 interventions were assessed separately and in combination.

Main Outcomes and Measures

Eligible patients' receipt of any valid dose of HPV vaccine during the study step.

Results

The cohort was comprised of 9242 11-year-olds (5165 [55.9%]) and 12-year-olds (4077 [44.1%]), and slightly more males (4848 [52.5%]). Parent reminder/recall resulted in 34.6% receiving a dose of HPV vaccine, health care professional audit/feedback, 30.4%, both interventions together resulted in 39.7%-all contrasted to usual care, 21.9%. Compared with usual care, the odds of HPV vaccination were higher for parent reminder/recall (odds ratio [OR], 1.56; 95% CI, 1.23-1.97) and for the combination of parent reminder/recall and health care professional audit/feedback (OR, 2.03; 95% CI, 1.44-2.85). Health care professional audit/feedback alone did not differ significantly from usual care (OR, 1.19; 95% CI, 0.94-1.51).

Conclusions and Relevance

In this cluster randomized trial, the combination of parent reminder/recall and health care professional audit/feedback increased the odds of HPV vaccination compared with usual care. These findings underscore the value of simultaneous implementation of evidence-based strategies to improve HPV vaccination.

Beyond Vaccination Coverage: Population-Based Measurement of Early Childhood Immunization Schedule Adherence

The immunization schedule recommended by the U.S. Advisory Committee on Immunization Practices (ACIP) provides a structure for how 10 different vaccine series should be administered to children in the first 18 months of life. Progress toward US early childhood immunization goals has largely focused on measuring vaccination coverage at age 24 months. However, standard vaccination coverage measures do not reflect whether children received vaccine doses by recommended ages, or whether vaccines were given concomitantly, per the schedule. In this paper, we describe innovations in population-level measurement of immunization schedule adherence through quantifying vaccination timeliness and undervaccination patterns. Measuring vaccination timeliness involves comparing when children received vaccine doses relative to ACIP age recommendations. To assess undervaccination patterns, children's vaccination histories are analyzed to determine whether they were vaccinated consistent with the ACIP schedule. Some patterns, such as spreading out vaccines across visits, are indicative of parental hesitancy. Other patterns, such as starting all recommended series but missing doses, are largely indicative of other immunization services delivery challenges. Since 2003, at least 12 studies have used National Immunization Survey-Child, immunization information system, or integrated health plan data to measure vaccination timeliness or undervaccination patterns at national or state levels. Moving forward, these novel measures can be leveraged for population-based surveillance of vaccine confidence, and for distinguishing undervaccination due to parental vaccine hesitancy from undervaccination due to other causes. Broader adoption of these measures can facilitate identification of targeted strategies for improving timely and routine early childhood vaccination uptake across the United States.

Vaccine-Related Errors in Reconstitution in South Korea: A National Physicians' and Nurses' Survey

Vaccine-related errors (VREs) result from mistakes in vaccine preparation, handling, storage, or administration. We aimed to assess physicians' and nurses' experiences of VREs in South Korea, focusing on reconstitution issues, and to understand the barriers to and facilitators of preventing them. This was a cross-sectional study using an internet-based survey to examine experiences of reconstitution-related errors, and experience or preference with regard to ready-to-use vaccines (RTU) by physicians and nurses. A total of 700 participants, including 250 physicians and 450 nurses, responded to the questionnaire. In total, 76.4% and 41.5% of the physicians and nurses, respectively, reported an error related to reconstituted vaccines. All errors had been reported as experienced by between 4.9% and 52.0% of physicians or nurses. The errors were reported to occur in more than one in 100 vaccinations for inadequate shaking of vaccines by 28.0% of physicians and 6.9% of nurses, incomplete aspiration of reconstitution vials by 28.0% of physicians and 6.4% of nurses, and spillage or leakage during reconstitution by 20.8% of physicians and 6.9% of nurses. A total of 94.8% of physicians had experience with RTU vaccines, and all preferred RTU formulations. In conclusion, this study highlights the high frequency and types of reconstitution-related errors in South Korea. RTU vaccines could help reduce the time needed for preparation and reduce the risk of errors in South Korea.

Development of a cumulative metric of vaccination adherence behavior and its application among a cohort of 12-month-olds in western Kenya

OBJECTIVES

The timely receipt of the recommended vaccination regimen, i.e. vaccination maintenance, is an underexplored, but important, indicator of public health. There is currently no standardized method for quantifying cumulative vaccination maintenance, however, and no simple way to explore predictors of adherence to vaccination schedules. We therefore sought to (1) develop a Vaccination Maintenance Score (VMS) and (2) apply this score to determine the predictors of vaccination behavior among infants in western Kenya (n = 245).

METHODS

Women in western Kenya were enrolled during pregnancy and surveyed repeatedly through one year postpartum. Data were collected on a range of sociodemographic and health indicators and vaccinations. For each infant, we analyzed receipt of 11 vaccines recommended by the Kenyan Ministry of Health. We operationalized VMS as the total number of vaccines received on schedule. Vaccines that were not received or received off schedule were scored 0. VMS was modeled using multivariable tobit regression models.

RESULTS

We found that 85.7% of infants were fully immunized, but only 42.4% had optimal VMS, i.e. scored 11. The median (IQR) VMS was 10 (3). In multivariable regression, each one-point increase in maternal quality of life score (range: 0-32) was associated with a 0.22-point increase in VMS; each additional child in the household was associated with a 0.34-point increase in VMS; and initiating breastfeeding at birth was associated a 2.01-point increase in VMS.

CONCLUSIONS

Coverage of the recommended vaccinations (85.7%) was nearly twice as high as cumulative timely receipt (42.4%). The VMS satisfies a need for a location-specific but easily adaptable metric of vaccination adherence behavior. It can be used to complement traditional methods of vaccination coverage and timeliness to better understand underlying behaviors that influence vaccination events, and thereby inform interventions to improve vaccination rates and decrease the burden of vaccine-preventable disease.

CLINICAL TRIAL REGISTRATION

NCT02974972 and NCT02979418.

Frequency and cost of live vaccines administered too soon after prior live vaccine in children aged 12 months through 6 years, 2014-2017

OBJECTIVE

To identify number of children who received live vaccines outside recommended intervals between doses and calculate corrective revaccination costs.

METHODS

We analyzed >1.6 million vaccination records for children aged 12 months through 6 years from six immunization information system (IIS) Sentinel Sites from 2014-15 when live attenuated influenza vaccine (LAIV, FluMist® Quadrivalent) was recommended for use, and from 2016-17, when not recommended for use. Depending on the vaccine, insufficient intervals between live vaccine doses are less than 24 or 28 days from a preceding live vaccine dose. Private and public purchase costs of vaccines were used to determine revaccination costs of live vaccine doses administered during the live vaccine conflict interval. Measles, mumps, rubella (MMR), varicella, combined MMRV, and LAIV were live vaccines evaluated in this study.

RESULTS

Among 946,659 children who received at least one live vaccine dose from 2014-15, 4,873 (0.5%) received at least one dose too soon after a prior live vaccine (revaccination cost, $786,413) with a median conflict interval of 16 days. Among 704,591 children who received at least one live vaccine dose from 2016-17, 1,001 (0.1%) received at least one dose too soon after a prior live vaccine (revaccination cost, $181,565) with a median conflict interval of 14 days. The live vaccine most frequently administered outside of the recommended intervals was LAIV from 2014-15, and varicella from 2016-17.

CONCLUSIONS

Live vaccine interval errors were rare (0.5%), indicating an adherence to recommendations. If all invalid doses were corrected by revaccination over the two time periods, the cost within the IIS Sentinel Sites would be nearly one million dollars. Provider awareness about live vaccine conflicts, especially with LAIV, could prevent errors, and utilization of clinical decision support functionality within IISs and Electronic Health Record Systems can facilitate better vaccination practices.

Frequency and Cost of Vaccinations Administered Outside Minimum and Maximum Recommended Ages-2014 Data From 6 Sentinel Sites of Immunization Information Systems

OBJECTIVE

To quantify vaccinations administered outside minimum and maximum recommended ages and to determine attendant costs of revaccination by analyzing immunization information system (IIS) records.

STUDY DESIGN

We analyzed deidentified records of doses administered during 2014 to persons aged <18 years within 6 IIS sentinel sites (10% of the US population). We quantified doses administered outside of recommended ages according to the Advisory Committee on Immunization Practices childhood immunization schedule and prescribing information in package inserts, and calculated revaccination costs. To minimize misreporting bias, we analyzed publicly funded doses for which reported lot numbers and vaccine types were consistent.

RESULTS

Among 3 394 047 doses with maximum age recommendations, 9755 (0.3%) were given after the maximum age. One type of maximum age violation required revaccination: 1344 (0.7%) of 194 934 doses of the 0.25-mL prefilled syringe formulation of quadrivalent inactivated influenza vaccine (Fluzone Quadrivalent, Sanofi Pasteur, Swiftwater, PA) were administered at age ≥36 months (revaccination cost, $111 964). We identified a total of 7 529 165 childhood, adolescent, and lifespan doses with minimum age recommendations, 9542 of which (0.1%) were administered before the minimum age. The most common among these violations were quadrivalent injectable influenza vaccines (3835, or 0.7% of 526 110 doses administered before age 36 months) and Kinrix (GlaxoSmithKline Biologicals, Rixensart, Belgium; DTaP-IPV) (2509, or 1.2% of 208 218 doses administered before age 48 months). The cost of revaccination for minimum age violations (where recommended) was $179 179.

CONCLUSION

Administration of vaccines outside recommended minimum and maximum ages is rare, reflecting a general adherence to recommendations. Error rates were higher for several vaccines, some requiring revaccination. Vaccine schedule complexity and confusion among similar products might contribute to errors. Minimization of errors reduces wastage, excess cost, and inconvenience for parents and patients.

Effective and sustainable advice line promotes safe vaccine practices

AIM

The SHOT LINE Telephone Assistance Resource provides consistent and timely education to healthcare providers ensuring safe delivery of immunizations.

BACKGROUND

A local health district created and implemented an advice line to assist healthcare personnel with immunization storage or administration questions. Healthcare workers with varying levels of education call with requests for information including vaccine administration, storage and handling, scheduling, contraindications, and timing.

METHODS

Ten years of call data to the SHOT LINE were analyzed through categorizing type of calls, personnel calling, facility type, information needed, and education provided.

RESULTS

There were 3032 calls received from various job types. The most frequent inquiries were vaccine-specific calls, timing, and vaccine schedules. Medical assistants from family medicine clinics called the most. Five percent of the calls included reports of immunization errors. Healthcare personnel reported errors and self-disclosed making errors; 7% of all calls were errors in the first 2 years, but decreased to 5.4% in the last 8 years.

CONCLUSION

The SHOT LINE telephone assistance provides timely education to healthcare personnel whose primary responsibilities are immunization practice management, administration, and handling. The findings reveal a significant need for timely advice in immunization practice management. Error reporting was an unexpected outcome of this advice line. Call categories of vaccine-specific information, vaccine timing, and schedules were similar across all groups of callers. The advice line has grown to include parents, school nurses, childcare providers, and emergency personnel. In summary, the SHOT LINE prevents errors, increases accuracy of vaccine management, and provides 'just in time' education.

Impact of pharmacist integration in a pediatric primary care clinic on vaccination errors: a retrospective review

OBJECTIVE

To measure the impact of ambulatory clinical pharmacist integration in a pediatric primary care clinic on vaccination error rates and to evaluate missed opportunities.

METHODS

A retrospective, quasi-experimental review of electronic medical records of visit encounters during a 3-month period compared vaccine error rates and missed opportunities between two pediatric residency primary care clinics. The intervention clinic has a full-time ambulatory clinical pharmacist integrated into the health care team. Pharmacy services were not provided at the comparison clinic. A vaccine error was defined as follows: doses administered before minimum recommended age, doses administered before minimum recommended spacing from a previous dose, doses administered unnecessarily, live virus vaccination administered too close to a previous live vaccine, and doses invalid for combinations of these reasons.

RESULTS

900 encounters were randomly selected and reviewed. The error rate was found to be 0.28% in the intervention clinic and 2.7% in the comparison clinic. The difference in error rates was found to be significant (P = 0.0021). The number of encounters with greater than or equal to one missed opportunity was significantly higher in the comparison clinic compared with the intervention clinic (29.3% vs. 10.2%; P <0.0001).

CONCLUSION

The pediatric primary care clinic with a pharmacist had reductions in vaccination errors as well as missed opportunities. Pharmacists play a key role in the pediatric primary care team to improve the appropriate use of vaccines.

Vaccination errors reported to the Vaccine Adverse Event Reporting System, (VAERS) United States, 2000-2013

IMPORTANCE

Vaccination errors are preventable events. Errors can have impacts including inadequate immunological protection, possible injury, cost, inconvenience, and reduced confidence in the healthcare delivery system.

OBJECTIVES

To describe vaccination error reports submitted to the Vaccine Adverse Event Reporting System (VAERS) and identify opportunities for prevention.

METHODS

We conducted descriptive analyses using data from VAERS, the U.S. spontaneous surveillance system for adverse events following immunization. The VAERS database was searched from 2000 through 2013 for U.S. reports describing vaccination errors and reports were categorized into 11 error groups. We analyzed numbers and types of vaccination error reports, vaccines involved, reporting trends over time, and descriptions of errors for selected reports.

RESULTS

We identified 20,585 vaccination error reports documenting 21,843 errors. Annual reports increased from 10 in 2000 to 4324 in 2013. The most common error group was "Inappropriate Schedule" (5947; 27%); human papillomavirus (quadrivalent) (1516) and rotavirus (880) vaccines were most frequently involved. "Storage and Dispensing" errors (4983; 23%) included mostly expired vaccine administered (2746) and incorrect storage of vaccine (2202). "Wrong Vaccine Administered" errors (3372; 15%) included mix-ups between vaccines with similar antigens such as varicella/herpes zoster (shingles), DTaP/Tdap, and pneumococcal conjugate/polysaccharide. For error reports with an adverse health event (5204; 25% of total), 92% were classified as non-serious. We also identified 936 vaccination error clusters (i.e., same error, multiple patients, in a common setting) involving over 6141 patients. The most common error in clusters was incorrect storage of vaccine (582 clusters and more than 1715 patients).

CONCLUSIONS

Vaccination error reports to VAERS have increased substantially. Contributing factors might include changes in reporting practices, increasing complexity of the immunization schedule, availability of products with similar sounding names or acronyms, and increased attention to storage and temperature lapses. Prevention strategies should be considered.

Evaluation of invalid vaccine doses in 31 countries of the WHO African Region

We examined (a) the fraction of and extent to which vaccinations were administered earlier than recommended (age-invalid) or with too short intervals between vaccine doses (interval-invalid) in countries of the World Health Organisation (WHO) African Region and (b) individual- and community-level factors associated with invalid vaccinations using multilevel techniques. Data from the Demographic and Health Surveys conducted in the last 10 years in 31 countries were used. Information about childhood vaccinations was based on vaccination records (n=134,442). Invalid vaccinations (diphtheria, tetanus, pertussis [DTP1, DTP3] and measles-containing vaccine (MCV)) were defined using the WHO criteria. The median percentages of invalid DTP1, DTP3 and MCV vaccinations across all countries were 12.1% (interquartile range, 9.4-15.2%), 5.7% (5.0-7.6%), and 15.5% (10.0-18.1%), respectively. Of the invalid DTP1 vaccinations, 7.4% and 5.5% were administered at child's age of less than one and two weeks, respectively. In 12 countries, the proportion of invalid DTP3 vaccinations administered with an interval of less than two weeks before the preceding dose varied between 30% and 50%. In 13 countries, the proportion of MCV doses administered at child's age of less than six months varied between 20% and 45%. Community-level variables explained part of the variation in invalid vaccinations. Invalid vaccinations are common in African countries. Timing of childhood vaccinations should be improved to ensure an optimal protection against vaccine-preventable infections and to avoid unnecessary wastage in these economically deprived countries.

Vaccination coverage and its determinants among migrant children in Guangdong, China

Background

Guangdong province attracted more than 31 million migrants in 2010. But few studies were performed to estimate the complete and age-appropriate immunization coverage and determine risk factors of migrant children.

Methods

1610 migrant children aged 12–59 months from 70 villages were interviewed in Guangdong. Demographic characteristics, primary caregiver’s knowledge and attitude toward immunization, and child’s immunization history were obtained. UTD and age-appropriate immunization rates for the following five vaccines and the overall series (1:3:3:3:1 immunization series) were assessed: one dose of BCG, three doses of DTP, OPV and HepB, one dose of MCV. Risk factors for not being UTD for the 1:3:3:3:1 immunization series were explored.

Results

For each antigen, the UTD immunization rate was above 71%, but the age-appropriate immunization rates for BCG, HepB, OPV, DPT and MCV were only 47.8%, 45.1%, 47.1%, 46.8% and 37.2%, respectively. The 1st dose was most likely to be delayed within them. For the 1:3:3:3:1 immunization series, the UTD immunization rate and age-appropriate immunization rate were 64.9% and 12.4% respectively. Several factors as below were significantly associated with UTD immunization. The primary caregiver’s determinants were their occupation, knowledge and attitude toward immunization. The child’s determinants were sex, Hukou, birth place, residential buildings and family income.

Conclusions

Alarmingly low immunization coverage of migrant children should be closely monitored by NIISS. Primary caregiver and child’s determinants should be considered when taking measures. Strategies to strengthen active out-reach activities and health education for primary caregivers needed to be developed to improve their immunization coverage.

Estimation of immunization providers' activities cost, medication cost, and immunization dose errors cost in Iraq

The immunization status of children is improved by interventions that increase community demand for compulsory and non-compulsory vaccines, one of the most important interventions related to immunization providers. The aim of this study is to evaluate the activities of immunization providers in terms of activities time and cost, to calculate the immunization doses cost, and to determine the immunization dose errors cost. Time-motion and cost analysis study design was used. Five public health clinics in Mosul-Iraq participated in the study. Fifty (50) vaccine doses were required to estimate activities time and cost. Micro-costing method was used; time and cost data were collected for each immunization-related activity performed by the clinic staff. A stopwatch was used to measure the duration of activity interactions between the parents and clinic staff. The immunization service cost was calculated by multiplying the average salary/min by activity time per minute. 528 immunization cards of Iraqi children were scanned to determine the number and the cost of immunization doses errors (extraimmunization doses and invalid doses). The average time for child registration was 6.7 min per each immunization dose, and the physician spent more than 10 min per dose. Nurses needed more than 5 min to complete child vaccination. The total cost of immunization activities was 1.67 US$ per each immunization dose. Measles vaccine (fifth dose) has a lower price (0.42 US$) than all other immunization doses. The cost of a total of 288 invalid doses was 744.55 US$ and the cost of a total of 195 extra immunization doses was 503.85 US$. The time spent on physicians' activities was longer than that spent on registrars' and nurses' activities. Physician total cost was higher than registrar cost and nurse cost. The total immunization cost will increase by about 13.3% owing to dose errors.

The Swiss National Vaccination Coverage Survey, 2005-2007

OBJECTIVES

We described the results from the Swiss National Vaccination Coverage Survey (SNVCS) 2005-2007, a survey designed to monitor immunization coverage of children and adolescents residing in Switzerland in each canton within a three-year period.

METHODS

The SNVCS is a cross-sectional survey using a two-stage sampling design targeting children aged 2, 8, and 16 years. Families of selected children were contacted by mail and telephone. Coverage was determined via vaccination cards or vaccination summary forms.

RESULTS

A total of 25 out of 26 cantons participated in the survey, with 8,286 respondents for children aged 24-35 months, 10,314 respondents for children aged 8 years, and 9,301 respondents for teenagers aged 16 years. Compared with data from 1999-2003, coverage estimates for toddlers remained unchanged for diphtheria, tetanus, pertussis, poliomyelitis, and Haemophilus influenzae type b vaccines at three doses, but increased five percentage points to 86%-87% for measles-mumps-rubella at one dose and was 71% at two doses. Coverage for measles, mumps, and rubella were 89%-90% at one dose and 75% at two doses for 8-year-olds, and 94% and 76% for the two dosages, respectively, for 16-year-olds. Linguistic region and nationality were highly correlated with being vaccinated against measles for the two younger age groups.

CONCLUSION

Despite the increase in vaccine coverage, measles vaccination is still low, and the World Health Organization goal to eliminate measles by 2010 was not achieved in Switzerland. More efforts are needed by the cantons and the central government to increase vaccination coverage.

Immunization status and risk factors of migrant children in densely populated areas of Beijing, China

OBJECTIVE

To properly evaluate the immunization status and determine risk factors of migrant children in 23 densely populated towns and townships in Beijing.

METHODS

A household cluster sampling survey was implemented and standard face-to-face interviews were conducted with 1820 migrant children aged 12-35 months. Demographic characteristics of the child and primary caregiver, the child's migrant characteristics, the primary caregiver's knowledge and attitude toward immunization, information about immunization services provided by the local clinic, and the child's immunization history were obtained. Weighted up-to-date (UTD) and age-appropriate immunization rates for the following four vaccines were assessed: three doses of diphtheria, tetanus and pertussis combined vaccine (DTP); three doses of oral poliomyelitis vaccine (OPV); three doses of hepatitis B vaccine (HepB); and one dose of Measles-containing vaccine (MCV). Weighted UTD and age-appropriate immunization rates for the overall series of these four vaccines (the 3:3:3:1 immunization series) were also estimated. Risk factors for not being UTD, being invalid and being delayed for the 3:3:3:1 immunization series were explored using both single-level and multi-level multinomial logistic regression models.

RESULTS

For each antigen, the weighted UTD immunization rate was above 83%, but the age-appropriate immunization coverages for HepB, OPV, DPT, and MCV were only 45.6%, 49.6%, 50.8% and 54.7%, respectively. The 1st dose was most likely to be invalid or delayed within HepB, OPV and DPT series. For the 3:3:3:1 immunization series, the weighted UTD and age-appropriate immunization rates were 78.1% and 20.5%, respectively. Immunization status of migrant children tended to be homogenous within a village and therefore, multi-level model was more appropriate for assessing risk factors. Besides demographic characteristics, several other factors were significantly associated with age-appropriate immunization coverage. These factors included: the child's migrant characteristics; the primary caregiver's awareness of the importance of vaccination, and outreach services provided by immunization clinics including notification services and supplementary immunization activities (SIAs). The frequency and duration of clinical immunization sessions significantly influenced the UTD immunization rate but not the age-appropriate immunization rate. The degree of the primary caregiver's satisfaction with clinic services and convenience to vaccination clinic had no impact on the child's immunization status.

CONCLUSION

Alarmingly low age-appropriate immunization coverage of migrant children in densely populated areas demanded immediate intervention. Community context was an important factor to a migrant child's vaccination status and should be considered when taking measures. Strategies to strengthen outreach immunization service need to be developed to effectively improve the age-appropriate immunization coverage of migrant children.

Evaluation of vaccine coverage for low birth weight infants during the first year of life in a large managed care population

OBJECTIVE

There are few recent population-based assessments of vaccine coverage in premature infants available. This study assesses and compares age- and dose-specific immunization coverage in children of different birth weight categories during the first year of life.

METHODS

We performed a retrospective cohort analysis of computerized vaccination data from a large managed care organization in southern California. The participants were children born between January 1, 1997, and December 31, 2002, and continuously enrolled from birth to at least 12 months of age in the Southern California Kaiser Permanente health plan. We measured age-specific up-to-date and age-appropriate immunization rates according to birth weight (extremely low birth weight: <1000 g; very low birth weight: 1000-1499 g; low birth weight: 1500-2499 g; normal birth weight: >/=2500 g) for 4 vaccines (hepatitis B, diphtheria and tetanus toxoids with pertussis, Haemophilus influenzae type b, and poliovirus) through the first year of life.

RESULTS

We identified 127 833 infants born during the study period and continuously enrolled through the first year of life; 120 048 were normal birth weight infants; 6491 were low birth weight infants; 788 were very low birth weight infants; and 506 were extremely low birth weight infants. Vaccine-specific age-appropriate immunization rates were 3% to 15% lower for low birth weight infants and 17% to 33% lower for extremely low birth weight infants compared with the rates for normal birth weight infants in the first 6 months of life. Extremely low birth weight infants had the lowest age-specific up-to-date immunization levels (5%-31% lower) compared with normal birth weight infants at each age assessed. By 12 months, extremely low birth weight infants still had significantly lower up-to-date levels (87%) compared with very low birth weight, low birth weight, and normal birth weight infants (91%-92%).

CONCLUSIONS

Despite recommendations that lower birth weight infants be vaccinated as the same chronological age as normal birth weight infants, extremely low birth weight and very low birth weight infants are immunized at significantly lower rates relative to low birth weight and normal birth weight infants at 2, 4, and 6 months of age. However, by 12 months of age this finding persists only in extremely low birth weight infants.

Compliance with vaccination recommendations for U.S. children

BACKGROUND

Official recommendations for the routine vaccination of U.S. children, made by the Advisory Committee on Immunization Practices (ACIP), specify the vaccines for administration, the number of doses that should be given, the age ranges for administration, the minimum ages at which doses are considered valid, the minimum intervals between doses within a series, and several additional vaccine-specific adjustments and exceptions. Federally reported estimates of vaccination coverage measure only compliance with the required number of doses; other recommendations are not routinely evaluated.

METHODS

Analysis of vaccination histories for 17,563 U.S. children aged 19-35 months from the 2005 National Immunization Survey.

MAIN OUTCOME MEASURES

Compliance with, and incremental impact of, each vaccination recommendation.

RESULTS

Estimated coverage was 72% for the standard vaccination series accounting for all recommendations, 9 percentage points lower than coverage based solely on counting doses. Overall, 19% of children were missing one or more doses, while 8% had received an invalid dose, and 9% were affected by other recommendations. The proportion of noncompliance due to missed doses versus other recommendations varied by state and by antigen.

CONCLUSIONS

Approximately 28% of children were not in compliance with the official vaccination recommendations. Missed doses accounted for approximately two thirds of noncompliance, with the remainder due to mis-timed doses and other requirements. Measuring compliance with all ACIP recommendations provides a valuable tool to assess and improve the quality of healthcare delivery and ensure that children and communities are optimally protected from vaccine-preventable diseases.

Vaccination coverage in 14-year-old adolescents: documentation, timeliness, and sociodemographic determinants

OBJECTIVE

The objective of this study was to measure the coverage and influencing determinants of hepatitis B virus, measles-mumps-rubella, and Meningococcus serogroup C vaccination in 14-year-old adolescents in Flanders, Belgium, in 2005.

METHODS

A total of 1500 adolescents who were born in 1991 and were living in Flanders were selected with a 2-stage cluster sampling technique. Home visits to copy vaccination documents and complete a questionnaire on sociodemographic and other related factors were conducted by trained interviewers. Only documented vaccination dates were accepted. Missing data were, when possible, retrieved through medical charts of the School Health System.

RESULTS

For 1344 (89.6%) adolescents, a home visit was performed. Vaccination coverage was 75.7% for the third dose of hepatitis B virus, 80.6% for the first dose and 83.6% for the second dose of measles-mumps-rubella, and 79.8% for Meningococcus serogroup C. Only 74.6% of the adolescents had proof of 2 measles-mumps-rubella vaccines. Although 1006 (74.8%) adolescents had vaccination data available at home at the time of the interview, only 427 (31.8%) were able to show written proof of all studied vaccines. The probably underestimated coverage rates are well below World Health Organization recommendations, but timeliness of vaccinations was respected. Univariate logistic regression showed that unemployment of the father as proxy measure of socioeconomic status was detrimental for vaccination status, in contrast to partial employment of the mother, which was a favorable factor. Previously unreported determinants of lower coverage rates inferred from this study are single divorced parents, larger families (> or = 4 children), lower adolescent educational level, enrollment in special education, and repeating a grade.

CONCLUSIONS

Insufficient documentation is a major barrier in this vaccination coverage study. More attention should go to those with the lowest coverage rates, such as adolescents from large families, with separated parents, and with a lower socioeconomic background.

Infant vaccination coverage in 2005 and predictive factors for complete or valid vaccination in Flanders, Belgium: an EPI-survey

To assess changes in infant vaccination coverage in Flanders since 1999, an EPI-survey was performed in 2005. The parents of 1354 children aged 18-24 months were interviewed at home and the vaccination documents were checked. Several factors possibly related to vaccination status were examined with parametric and non-parametric methods. The coverage rate of recommended vaccines, i.e. poliomyelitis, tetanus-diphtheria-pertussis, H. influenzae type b (Hib), hepatitis B, measles-mumps-rubella (MMR) and meningococcal C, reached at least 92.2%, which is a significant rise for MMR, hepatitis B and Hib since 1999. The vaccinating physician, the employment situation of the mother and the family income were significant predictive factors for having received all recommended vaccine doses (complete schedule), also when considering only doses that were according to minimal age and interval criteria (valid schedule).

Compliance with national immunization guidelines for children younger than 2 years, 1996-1999

OBJECTIVES

To evaluate compliance with national immunization guidelines among a large cohort of children cared for at health maintenance organizations (HMOs) and to examine effects on immunization status.

METHODS

A cohort study of 176134 children born between January 1, 1994, and December 31, 1997, and monitored from birth to the second birthday was performed. Subjects belonged to the Vaccine Safety Datalink Project, a study of children enrolled in 1 of 4 HMOs. Children were continuously enrolled in a HMO for the first 2 years of life. Prevailing recommendations regarding optimal ages of immunization and intervals between doses were applied to define appropriate immunization timing and immunization status. Noncompliance was defined as having a missing or late immunization or an immunization error. Immunization errors included invalid immunizations (too early to be acceptable), extra immunizations (superfluous immunizations or make-up immunizations for invalid immunizations), and missed opportunities resulting in late or missing immunizations.

RESULTS

Although 75.4% of children in these HMOs were up to date for all immunizations at 2 years, only 35.6% of children were fully compliant with recommended immunization practices. Less than 8% of children received all immunizations in accordance with strict interpretation of recommended guidelines. Fifty-one percent of children had at least 1 immunization error by age 2 years; 29.7% had a missed opportunity with subsequent late or missing immunization, 20.4% had an invalid immunization, and 11.6% had an extra immunization. Common reasons for noncompliance included missed opportunities for the fourth Haemophilus influenzae type b vaccine (14.6%), invalid fourth diphtheria-tetanus-pertussis/acellular pertussis immunizations (11.0%), and superfluous polio immunizations (9.8%).

CONCLUSIONS

Approximately 35.6% of children were compliant with prevailing childhood immunization recommendations from 1996 to 1999. Efforts to improve compliance with guidelines are recommended, to optimize childhood infectious disease prevention.