Vaccination visits in early childhood: just one more visit to be fully vaccinated

Failure to Complete Multidose Vaccine Series in Early Childhood

BACKGROUND

Most early childhood immunizations require 3 to 4 doses to achieve optimal protection. Our objective was to identify factors associated with starting but not completing multidose vaccine series.

METHODS

Using 2019 National Immunization Survey-Child data, US children ages 19 to 35 months were classified in 1 of 3 vaccination patterns: (1) completed the combined 7-vaccine series, (2) did not initiate ≥1 of the 7 vaccine series, or (3) initiated all series, but did not complete ≥1 multidose series. Associations between sociodemographic factors and vaccination pattern were evaluated using multivariable log-linked binomial regression. Analyses accounted for the survey's stratified design and complex weighting.

RESULTS

Among 16 365 children, 72.9% completed the combined 7-vaccine series, 9.9% did not initiate ≥1 series, and 17.2% initiated, but did not complete ≥1 multidose series. Approximately 8.4% of children needed only 1 additional vaccine dose from 1 of the 5 multidose series to complete the combined 7-vaccine series. The strongest associations with starting but not completing multidose vaccine series were moving across state lines (adjusted prevalence ratio [aPR] = 1.45, 95% confidence interval [CI]: 1.18-1.79), number of children in the household (2 to 3: aPR = 1.29, 95% CI: 1.05-1.58; 4 or more: aPR = 1.68, 95% CI: 1.30-2.18), and lack of insurance coverage (aPR = 2.03, 95% CI: 1.42-2.91).

CONCLUSIONS

More than 1 in 6 US children initiated but did not complete all doses in multidose vaccine series, suggesting children experienced structural barriers to vaccination. Increased focus on strategies to encourage multidose series completion is needed to optimize protection from preventable diseases and achieve vaccination coverage goals.

Determinants of under-immunization and cumulative time spent under-immunized in a Quebec cohort

BACKGROUND

Under-immunization refers to a state of sub-optimal protection against vaccine preventable diseases. Vaccine coverage for age may not capture intentional or non-intentional spacing of vaccines in the recommended provincial immunization guidelines. We aimed to identify factors associated with coverage and under-immunization and to determine the number of days during which children were under-immunized during their first 24months of life.

METHODS

Secondary analysis of children ≤3years recruited through active surveillance for gastroenteritis from three Quebec pediatric emergency departments from 2012 to 2014. Vaccination status for children at least 24months of age was determined using provincial immunization guidelines. Cumulative days under-immunized were calculated for DTaP-VPI-Hib, PCV, MMR, and Men-C-C. Factors associated with up-to-date (UTD) status at 24months of life and for under-immunization ≥6months were analyzed using logistic regression.

RESULTS

Of 246 eligible children, 180 (73%) were UTD by 24months of life. The mean cumulative days under-immunized for MMR was 107days, for PCV 209days, for Men-C-C 145days, and for DTaP-VPI-Hib 227days. Overall, 149 children (60%) experienced delay for at least 1 vaccine. Factors associated with both an UTD status at 24months and concurrently associated with being under-immunization ≥6months, included timely initiation of immunization (OR=5.85; 95% CI: 2.80-12.22) and (OR=0.13; 95% CI: 0.07-0.24), failure to co-administer 18-month vaccines (OR=0.15; 95% CI: 0.10-0.21) and (OR=3.29; 95% CI: 2.47-4.39), and having a household with ≥3 children under 18years ((OR=0.50; 0.28-0.86) and (OR=2.99; 1.45-6.22), respectively.

CONCLUSION

Paired with an unexpected low level of coverage at 24months of life, the majority of our cohort also experienced a state of under-immunization for a least one vaccine. Estimates of coverage do not capture intentional or non-intentional gaps in protection from vaccine preventable illnesses. Timely preventive care should be prioritized.

Missed opportunities for simultaneous administration of the fourth dose of DTaP among children in the United States

BACKGROUND

Simultaneous administration of all age-appropriate doses of vaccines is an effective strategy for raising vaccination coverage. Vaccination coverage for ≥4 dose of DTaP (diphtheria, tetanus toxoids, and acellular pertussis vaccine) among children 19-35months in the United States has not reached the Healthy People 2020 target of 90%. Risk factors for missed opportunities for simultaneous administration of the fourth dose of DTaP have not been investigated.

METHODS

A missed opportunity for simultaneous administration of the fourth dose of DTaP is defined as the failure to administer an age-eligible fourth dose of DTaP, and during the same age-eligible period for the fourth dose of DTaP other recommended and age-appropriate doses of vaccines are given to children. This study used 2001-2014 National Immunization Survey data to describe the trend in missed opportunities for simultaneous administration of the fourth dose of DTaP from 2001 through 2014, assess the prevalence of children who missed opportunities for simultaneous administration of the fourth dose of DTaP by selected factors, and recognize significant risk factors for missed opportunities for simultaneous administration of the fourth dose of DTaP.

RESULTS

From 2001 to 2014, the prevalence of missed opportunities for simultaneous administration of the fourth dose of DTaP among children 19-35months in the United States ranged from 5.7% to 9.0%; across 13 factors considered, the prevalence of missed opportunities varied from 3.3% to 22.9%. Children who were late in receiving the first to third dose of DTaP had significantly higher prevalence of missed opportunities for simultaneous administration of the fourth dose of DTaP than children who received these doses on-time, with adjusted prevalence ratios for late vs. on-time of 1.7, 1.6, and 3.2, and all P-value<0.01.

CONCLUSIONS

Improving on-time vaccination of the third dose of DTaP could substantially reduce missed opportunities for simultaneous administration of the fourth dose of DTaP.

A current and historical perspective on disparities in US childhood pneumococcal conjugate vaccine adherence and in rates of invasive pneumococcal disease: Considerations for the routinely-recommended, pediatric PCV dosing schedule in the United States

Previous research has suggested that reducing the US 4-dose PCV13 schedule to a 3-dose schedule may provide cost savings, despite more childhood pneumococcal disease. The study also stressed that dose reduction should be coupled with improved PCV adherence, however, US PCV uptake has leveled-off since 2008. An estimated 24–36% of US children aged 5–19 months are already receiving a reduced PCV schedule (i.e., missing ≥1 dose). This raises a practical concern that, under a reduced, 3-dose schedule, a similar proportion of children may receive ≤2 doses. It is also unknown if a reduced, 3-dose PCV schedule in the United States will afford the same disease protection as 3-dose schedules used elsewhere, given lower US PCV adherence. Finally, more assurance is needed that, under a reduced schedule, racial, socioeconomic, and geographic disparities in PCV adherence will not correspond with disproportionately higher rates of pneumococcal disease among poor or minority children.

Risk Factors Associated with Children Missing the Fourth Dose of DTaP Vaccination

BACKGROUND

In 2012, reported pertussis reached the highest number of cases (48,277) in the United States since 1955.

OBJECTIVES

Estimate the prevalence of children who missed the fourth dose of DTaP (Diphtheria and Tetanus toxoids and acellular Pertussis vaccine) by parents' confidences in vaccines and influences from providers, the timeliness of the first through the third dose of DTaP, and selected socio-demographic characteristics; identify the significant risk factors for non-receipt of the fourth dose of DTaP; and evaluate the unadjusted and adjusted risk ratios for missing the fourth dose of DTaP.

METHODS

Data from 16,919 children 19-35 months living in the United States included in the 2011 National Immunization Survey were analyzed. Weighted categorical data analysis and multivariable regression in the context of complex sample survey were applied to assess the prevalence and to determine the independent risk factors.

RESULTS

Overall, 14.7% of children missed the fourth dose of DTaP. Children who were late in receiving the third dose of DTaP had significantly higher risk of missing the fourth dose of DTaP than children who were on-time in receiving the third dose of DTaP (adjusted risk ratio (RR) 2.48; 95%CI (1.92, 3.20)). The risk of missing the fourth dose of DTaP was 62% higher among children whose parents reported they didn't have a good relationship with their child's health-care providers than children whose parents reported having good relationship. Compared with the risk of missing the fourth dose of DTaP among children whose parents were confident in the value of vaccines, the risk was significantly higher for the children whose parents lacked confidence (adjusted RR 1.41; 95%CI (1.05, 1.89)).

CONCLUSIONS

Timeliness in receiving the first through the third dose of DTaP, influences from providers, and parents' confidence in the value of vaccines are the five significant risk factors for missing the fourth dose of DTaP vaccination. They are all modifiable. Future interventions to improve parental relationships with providers and attitudes toward vaccines could help improve pertussis vaccination coverage.

Epidemiology and Control: Principles, Practice and Programs

Infectious disease epidemiology is concerned with the occurrence of both infection and disease in populations and the factors that determine their frequency, spread, expression and distribution. Viruses show characteristic infectivity, virulence and pathogenicity. The most well established host factors are age, sex and race, but other host biological and behavioral factors affect acquisition of viral infection and/or its course and manifestations. The physical, chemical and biological environment operates on the virus itself and may also alter the host biological or behavioral response. Viral infections have incubation periods lasting days or weeks, while their pathologic sequelae may not manifest for years or decades. Likewise the degree or intensity of host response and clinical expression may range from largely inapparent to highly lethal. The degree of cell, tissue and organ specificity is high. Common syndromes involve the respiratory, gastrointestinal, and central nervous systems, the liver, and mucocutaneous surfaces. Vertical transmission may produce a variety of congenital and perinatal conditions. Viruses spread by multiple modes, using nearly every bodily surface or fluid as a route of exit or entry, either by direct contact or indirectly through an animal vector or other inanimate vehicle. Different viral Infections occur nearly ubiquitously or sporadically; they may be present continuously throughout a population (endemic) or occur in seasonal rhythm or in unexpectedly explosive form (epidemic). Many viruses are refractory to all known therapeutic agents, while for a few, the increasing number of highly effective agents holds great promise. Vaccines have produced many historical successes including the ultimate goal of eradication, but many viral infections continue to elude effective vaccine development. Major government and private sector programs for treatment and prevention have raised expectations of successful control for certain widespread and serious viral diseases; however, in every case a unique set of scientific, socioeconomic, political and behavioral barriers remains to be overcome.

A longitudinal analysis of the effect of nonmedical exemption law and vaccine uptake on vaccine-targeted disease rates

OBJECTIVES

We assessed how nonmedical exemption (NME) laws and annual uptake of vaccines required for school or daycare entry affect annual incidence rates for 5 vaccine-targeted diseases: pertussis, measles, mumps, Haemophilus influenzae type B, and hepatitis B.

METHODS

We employed longitudinal mixed-effects models to examine 2001-2008 vaccine-targeted disease data obtained from the National Notifiable Disease Surveillance System. Key explanatory variables were state-level vaccine-specific uptake rates from the National Immunization Survey and a state NME law restrictiveness level.

RESULTS

NME law restrictiveness and vaccine uptake were not associated with disease incidence rate for hepatitis B, Haemophilus influenzae type B, measles, or mumps. Pertussis incidence rate, however, was negatively associated with NME law restrictiveness (b = -0.20; P = .03) and diphtheria-pertussis-tetanus vaccine uptake (b = -0.01; P = .05).

CONCLUSIONS

State NME laws and vaccine uptake rates did not appear to influence lower-incidence diseases but may influence reported disease rates for higher-incidence diseases. If all states increased their NME law restrictiveness by 1 level and diphtheria-pertussis-tetanus uptake by 1%, national annual pertussis cases could decrease by 1.14% (171 cases) and 0.04% (5 cases), respectively.

Patterns of rotavirus vaccine uptake and use in privately-insured US infants, 2006-2010

Rotavirus vaccines are highly effective at preventing gastroenteritis in young children and are now universally recommended for infants in the US. We studied patterns of use of rotavirus vaccines among US infants with commercial insurance. We identified a large cohort of infants in the MarketScan Research Databases, 2006-2010. The analysis was restricted to infants residing in states without state-funded rotavirus vaccination programs. We computed summary statistics and used multivariable regression to assess the association between patient-, provider-, and ecologic-level variables of rotavirus vaccine receipt and series completion. Approximately 69% of 594,117 eligible infants received at least one dose of rotavirus vaccine from 2006-2010. Most infants received the rotavirus vaccines at the recommended ages, but more infants completed the series for monovalent rotavirus vaccine than pentavalent rotavirus vaccine or a mix of the vaccines (87% versus 79% versus 73%, P<0.001). In multivariable analyses, the strongest predictors of rotavirus vaccine series initiation and completion were receipt of the diphtheria, tetanus and acellular pertussis vaccine (Initiation: RR = 7.91, 95% CI = 7.69-8.13; Completion: RR = 1.26, 95% CI = 1.23-1.29), visiting a pediatrician versus family physician (Initiation: RR = 1.51, 95% CI = 1.49-1.52; Completion: RR = 1.13, 95% CI = 1.11-1.14), and living in a large metropolitan versus smaller metropolitan, urban, or rural area. We observed rapid diffusion of the rotavirus vaccine in routine practice; however, approximately one-fifth of infants did not receive at least one dose of vaccine as recently as 2010. Interventions to increase rotavirus vaccine coverage should consider targeting family physicians and encouraging completion of the vaccine series.

Incomplete Early Childhood Immunization Series and Missing Fourth DTaP Immunizations; Missed Opportunities or Missed Visits?

The successful completion of early childhood immunizations is a proxy for overall quality of early care. Immunization statuses are usually assessed by up-to-date (UTD) rates covering combined series of different immunizations. However, series UTD rates often only bear on which single immunization is missing, rather than the success of all immunizations. In the US, most series UTD rates are limited by missing fourth DTaP-containing immunizations (diphtheria/tetanus/pertussis) due at 15 to 18 months of age. Missing 4th DTaP immunizations are associated either with a lack of visits at 15 to 18 months of age, or to visits without immunizations. Typical immunization data however cannot distinguish between these two reasons. This study compared immunization records from the Oregon ALERT IIS with medical encounter records for two-year olds in the Oregon Health Plan. Among those with 3 valid DTaPs by 9 months of age, 31.6% failed to receive a timely 4th DTaP; of those without a 4th DTaP, 42.1% did not have any provider visits from 15 through 18 months of age, while 57.9% had at least one provider visit. Those with a 4th DTaP averaged 2.45 encounters, while those with encounters but without 4th DTaPs averaged 2.23 encounters.

Financial impact to providers using pediatric combination vaccines

OBJECTIVE

To understand the financial impact to providers for using a combination vaccine (Pediarix [GlaxoSmithKline Biologicals, King of Prussia, PA]) versus its equivalent component vaccines for children aged 1 year or younger.

METHODS

Using a subscription remittance billing service offered to private-practice office-based physicians, we analyzed charge and payment information submitted by providers to insurance payers from June 2007 through July 2009. We analyzed provider and payer characteristics, payer comments, and the ratio of vaccine product to immunization administration (IA) codes and computed total charges and payments to providers for both arms of the study.

RESULTS

Most providers in our data set were pediatricians (74%), and most payers were commercial (75%), primarily managed care. The ratio of the number of vaccine products to the number of IAs was 1:1 in the majority of the claims. Twenty percent of claims were paid with no adjustment by the payer, whereas 76% of the claims were adjusted for charges that exceeded the contract arrangement or the fee schedule. Providers received $23 less from commercial payers and $13 less from Medicaid for the use of Pediarix compared with the equivalent component vaccines. The mean commercial payment was greater for age-specific Current Procedural Terminology IA codes 90465 and 90466 than for non-age-specific codes 90471 and 90472, whereas the reverse was true for Medicaid.

CONCLUSIONS

Providers who administer vaccines to children face a reduction in payment when choosing to provide combination vaccines. The new IA codes should be monitored for correction of financial barriers to the use of combination vaccines.

Improving immunization rates at 18 months of age: implications for individual practices

OBJECTIVE

We sought to model the effect that a targeted immunization visit at 18 months of age could have on immunization rates of preschool-aged children in a sample of pediatric practices.

METHODS

We conducted retrospective chart reviews in six practices of all active patients aged 18-30 months. Up-to-date (UTD) status was defined as receipt of four diphtheria-tetanus-acellular pertussis, three polio, one measles-mumps-rubella, three hepatitis B, and one varicella vaccines. Haemophilus influenza tybe b vaccine was not included due to a shortage in vaccine supply during the time of the study. Practice vaccination rates were determined at 17 months, 18 months, and the age at assessment. Of those not UTD at 17 months, the percentage of children who could be brought UTD with one visit was calculated for each practice. This calculated rate was compared with the measured rate at 18 months of age and at the age of assessment.

RESULTS

At each practice, we reviewed 183-616 charts (median = 382). Observed UTD immunization rates at 17 months ranged from 26% to 64% (median = 38%) and increased 3 to 27 percentage points (median = 6) from age 17 months to 18 months and 9 to 39 percentage points (median = 17) from age 17 months to the age at assessment. A simulated vaccination visit at 18 months of age could improve the UTD rates from 27 to 61 percentage points (median = 44).

CONCLUSION

Practice-based interventions aimed at encouraging an 18-month well-child visit that emphasizes delivery of vaccines have the potential to substantially increase timely vaccination rates among individual practices.

Immunization milestones: a more comprehensive picture of age-appropriate vaccination

A challenge facing immunization registries is developing measures of childhood immunization coverage that contain more information for setting policy than present vaccine series up-to-date (UTD) rates. This study combined milestone analysis with provider encounter data to determine when children either do not receive indicated immunizations during medical encounters or fail to visit providers. Milestone analysis measures immunization status at key times between birth and age 2, when recommended immunizations first become late. The immunization status of a large population of children in the Oregon ALERT immunization registry and in the Oregon Health Plan was tracked across milestone ages. Findings indicate that the majority of children went back and forth with regard to having complete age-appropriate immunizations over time. We also found that immunization UTD rates when used alone are biased towards relating non-UTD status to a lack of visits to providers, instead of to provider visits on which recommended immunizations are not given.

When and why children fall behind with vaccinations: missed visits and missed opportunities at milestone ages

OBJECTIVE

Little is known about when-and why-children fall behind in their recommended vaccinations. Vaccination status throughout the first 2 years of life was examined to identify vulnerable transition periods that account for attrition and to determine whether children fell behind because they missed vaccination visits or because of missed opportunities for simultaneous vaccination.

METHODS

Vaccination histories for 27,083 children aged 24-35 months in the 2006-2007 National Immunization Survey were analyzed to determine the vaccination status at each age in days, focusing on the milestone ages of 3, 5, 7, 16, 19, and 24 months. Also assessed were the percentage of children who fell behind between milestones and the percentage who did so due to the lack of a vaccination visit compared to a missed opportunity for simultaneous vaccination.

RESULTS

The percentage of children who fell behind from one milestone age to the next ranged from 9% during the interval from age 16 months to 19 months to 20% during the interval from age 7 months to age 16 months. Missed vaccination visits accounted for most attrition during the intervals from age 3 months to age 5 months, age 5 months to age 7 months, and age 16 months to age 19 months, while missed opportunities for simultaneous vaccination accounted for >90% of the children who fell behind during the interval from age 7 months to age 16 months.

CONCLUSIONS

Missed vaccination visits and missed opportunities for simultaneous vaccinations both must be addressed to reduce the number of children falling behind in their vaccinations. With one in five children falling behind during the interval from age 7 months to age 16 months--mostly as a result of missed opportunities for simultaneous vaccination--providers should focus on this time interval to deliver all of the recommended vaccinations that are due.

Vaccination coverage estimates for selected counties: achievement of Healthy People 2010 goals and association with indices of access to care, economic conditions, and demographic composition

OBJECTIVES

We provided vaccination coverage estimates for 181 counties; evaluated the extent to which Healthy People 2010 (HP 2010) vaccination coverage objectives were achieved; and examined how variations in those estimates depend on access to care and economic conditions.

METHODS

We analyzed data for 24,031 children aged 19 to 35 months sampled from the 2004 and 2005 National Immunization Survey.

RESULTS

Children living in the 181 counties represented 49% of all the 19- to 35-month-old children living in the U.S. None of the 181 counties had coverage for the polio, measles-mumps-rubella, Haemophilus influenzae type B, and hepatitis B vaccines that was significantly lower than the HP 2010 objective of 90% coverage. However, as many as 30.4% of the counties did not achieve the HP 2010 objective for diphtheria, tetanus toxoids, and acellular pertussis or diphtheria and tetanus toxoids and pertussis (DtaP/DTP), and as many as 6.6% did not achieve the goal for varicella (VAR). If children who received three doses of DTaP/DTP had received a final fourth dose, and if all children had received one dose of VAR, all of the 181 counties would have achieved the HP 2010 vaccination coverage target of 80% for the entire 4:3:1:3:3:1 vaccination series. Factors found to be associated with low county-level vaccination coverage rates were correlates of poverty, and factors found to be associated with high county-level vaccination coverage rates were correlates of access to pediatric services.

CONCLUSIONS

HP 2010 vaccination coverage goals for all 181 counties can be achieved by improving vaccination coverage for only two vaccines. Those goals may be achieved most efficiently by targeting interventions in counties where indices of poverty are high or where access to pediatric services is low.

Identifying risk factors for underimmunization by using geocoding matched to census tracts: a statewide assessment of children in Hawaii

OBJECTIVE

Obtaining childhood immunization coverage data for small geographic areas is difficult and resource-intensive, especially in the absence of comprehensive immunization registries. To identify factors that are associated with delayed immunization, we collected school-entry immunization records statewide and used geocoding to link to publicly available census tract sociodemographic data.

METHODS

Immunization records were reviewed for children who were enrolled in all public and private school kindergarten programs in Hawaii in the 2002-2003 school year; immunization status at the time of the second birthday was determined. The main outcome variable was up-to-date status for the 4:3:1:3:3 vaccination series (4 doses of diphtheria-tetanus-pertussis, 3 doses of polio, 1 dose of measles-mumps-rubella, 3 doses of Haemophilus influenzae type b, and 3 doses of hepatitis B vaccines). Children's home addresses were geocoded to census tracts; coverage rates by tract were mapped, and sociodemographic data from Census 2000 files were used to identify factors that were associated with delays in immunization.

RESULTS

Records were obtained for 15,275 of 15,594 children registered in Hawaii kindergartens. Overall, 78% had completed their 4:3:1:3:3 series by their second birthday. Risk factors for delayed immunization included delayed immunization at 3 months of age, living in Maui County, living in a neighborhood where a low proportion of adults had postsecondary education, and living in a neighborhood where a high proportion of households spoke a language other than English at home. The majority (80%) of underimmunized children would have required only 1 additional visit to bring them up-to-date.

CONCLUSIONS

Retrospective review of kindergarten-entry immunization data revealed geographic areas with lower immunization coverage, and geocoding to census tracts identified associated sociodemographic risk factors. This is a practical method for state or city health departments to identify pockets of need and to direct resources appropriately.

Preventive care for children in the United States: quality and barriers

Our objective was to examine the academic literature covering quality of childhood preventive care in the United States and to identify barriers that contribute to poor or disparate quality. We systematically reviewed articles related to childhood preventive care published from 1994 through 2003, focusing on 58 large observational studies and interventions addressing well-child visit frequency, developmental and psychosocial surveillance, disease screening, and anticipatory guidance. Although many children attend recommended well-child visits and receive comprehensive preventive care at those visits, many do not attend such visits. Estimates of children who attend all recommended visits range widely (from 37%-81%). In most studies, less than half is the proportion of children who receive developmental or psychosocial surveillance, adolescents who are asked about various health risks, children at risk for lead exposure who are screened, adolescents at risk for Chlamydia who are tested, or children and adolescents who receive anticipatory guidance on various topics. Major barriers include lack of insurance, lack of continuity with a clinician or place of care, lack of privacy for adolescents, lack of clinician awareness or skill, racial/ethnic barriers, language-related barriers, clinician and patient gender-related barriers, and lack of time. In summary, childhood preventive care quality is mixed, with large disparities among populations. Recent research has identified barriers that might be overcome through practice and policy interventions.

Vaccination coverage in the South-East Anatolian Project (SEAP) region and factors influencing low coverage

OBJECTIVES

To determine the vaccination coverage of children living in the South-east Anatolian Project (SEAP) region; whether the vaccination coverage was similar to formal reports, other studies and other countries; and which factors influence vaccination, in order to indicate how vaccination coverage can be improved.

STUDY DESIGN

A descriptive cross-sectional study conducted in nine provinces of the SEAP region in order to determine public health problems and their causes.

METHODS

A population-based sample of 1150 houses was selected from rural and urban areas of the SEAP region and visited by the researchers. Questionnaires were applied in 2001 and 2002.

RESULTS

In the SEAP region, only 30% of children had received a complete set of vaccines. The vaccination coverage was 76.7% for Bacille Calmette-Guérin; 62.0% for the third doses of diphtheria, tetanus toxoid, pertussis and polio vaccine; 62.7% for measles; 44% for the third dose of hepatitis B vaccine in children aged 12-23 months; and 13.3% for the second dose of tetanus toxoid in women who gave birth in the last 5 years. In logistic regression analysis, residence type, number of siblings, birth interval, follow-up visits of midwives, and maternal level of education were found to influence whether children were completely vaccinated.

CONCLUSIONS

The findings of this study indicate that vaccination coverage is not acceptable in the SEAP region. Efforts must focus on family planning services, education of women, follow-up visits and strengthening health facilities, especially in rural regions, to improve vaccination.

The Taiwan National Health Insurance program and full infant immunization coverage

OBJECTIVES

We compared hospital-born infants and well-baby care use associated with complete immunizations in Taiwan before and after institution of National Health Insurance (NHI).

METHODS

We used logistic regression to analyze data from 1989 and 1996 National Maternal and Infant Health Surveys of 1398 and 3185 1-year-old infants, respectively.

RESULTS

Infants born in hospitals were found to receive fewer immunizations than those born elsewhere before NHI but significantly more after NHI. Use of well-baby care correlates strongly and positively with the probability that a child will receive a full course of immunization after NHI.

CONCLUSIONS

The NHI policy of including hospitals as immunization providers facilitates access to immunization services for children born in those facilities. Through NHI provision of free well-baby care, health planners have stimulated the demand for immunization.

Missed opportunities for adult immunization in diverse primary care office settings

Adult vaccination rates are well below national goals of 90%. We examined medical records of 810 adults > or =65 years to determine number and type of visits, discussion and patient refusals of vaccines, influenza vaccinations over three seasons, and pneumococcal and tetanus vaccinations over 5 years. From the medical record, immunization rates were 24.1% for annual influenza, 49.1% for pneumococcal polysaccharide and 28.6% for tetanus vaccine. During the 27 month study period, patients averaged 1.3 +/- 1.9 acute visits, 6.9 +/- 5.1 chronic visits and 0.48 +/- 0.91 preventive visits (mean +/- S.D.). Missed opportunities to vaccinate ranged from 38.4 to 94.5% of visits. Vaccination rates were higher if medical records included health maintenance flow sheets. Failure to discuss vaccination, to vaccinate at acute care visits, and low frequency of preventive visits resulted in missed opportunities to vaccinate. A health maintenance flow sheet can prompt providers to discuss vaccination and record vaccines as they are administered.

Racial/ethnic disparities in preschool immunizations: United States, 1996-2001

OBJECTIVES

We examined current racial/ethnic differences in immunization coverage rates among US preschool children.

METHODS

Using National Immunization Survey data from 1996 through 2001, we compared vaccination coverage rates between non-Hispanic White, non-Hispanic Black, Hispanic, and Asian preschool children.

RESULTS

During the 6-year study period, the immunization coverage gap between White and Black children widened by an average of 1.1% each year, and the gap between White and Hispanic children widened by an average of 0.5% each year. The gap between White and Asian children narrowed by an average of 0.8% each year.

CONCLUSIONS

Racial/ethnic disparities in preschool immunization coverage rates have increased significantly among some groups; critical improvements in identifying, understanding, and addressing race/ethnicity-specific health care differences are needed to achieve the Healthy People 2010 goal of eliminating disparities.

Remove vaccination barriers for children 12 to 24 months

Vaccinations were one of the top ten public health achievements of the 20th century, yet currently more than 900,000 U.S. children aren't properly immunized. The purpose of this study was to increase compliance rates in children 12 to 24 months from 38% to 80%. This was done by determining what factors impacted compliance and by instituting an immunization surveillance program.

Predictors of age-appropriate receipt of DTaP dose 4

BACKGROUND

In the United States, the national childhood immunization schedule calls for children to receive four doses of DTaP (diphtheria and tetanus toxoids and acellular pertussis) vaccine administered at 2, 4, 6, and 15 to 18 months. Dose 4 of DTaP is among the most frequently missed vaccines for children who are not adequately immunized.

METHODS

Using the 2001 National Immunization Survey, the effect of the timeliness of the first three DTaP doses was assessed on completion of the four-dose series by age 24 months and on time by age 12 to 18 months.

RESULTS

Missing Dose 4 was more prevalent among children who received Dose 3 late (but <16 months) than among children who received Dose 3 on time (24% vs 10%). Similarly, receiving Dose 4 late (or not at all) was more prevalent among children who received Dose 3 late (but <9 months) (39% vs 22%). An invalid Dose 4 was administered to 4.6% of those with Dose 3 late but before 9 months and to 10.6% of those with no Dose 3 before 9 months, compared to 1.2% of those with Dose 3 on time.

CONCLUSIONS

Physicians and staff can identify children at risk for missing the fourth DTaP dose or receiving it late by assessing timeliness of receipt of DTaP Dose 3 and implementing steps to ensure that at-risk children receive Dose 4 as recommended.

Timeliness of childhood immunizations

OBJECTIVE

To examine the timeliness of vaccine administration among infants and young children in the United States.

METHODS

We analyzed age at receipt of vaccines among 16 211 children aged 24 to 35 months in the 2000 National Immunization Survey and examined receipt at the recommended time of each dose and selected vaccination series, as well as receipt at 4 additional time frames: acceptably early, late, never by 24 months, and too early to be considered valid. We also examined the relationship between timeliness of vaccinations and characteristics of the child, mother, and immunization provider, using multivariate logistic regression.

RESULTS

Only 9% of children received all recommended vaccines at the recommended ages. The rates varied significantly by antigen, ranging from 24% for all Haemophilus influenzae type b doses to 75% for all hepatitis B doses as recommended. Overall, 55% of children did not receive all recommended doses by 24 months of age, and 8% of children received at least 1 vaccination dose too early to be considered valid. Factors associated with not receiving all vaccines as recommended were having more children in the household, mothers younger than 30 years, use of public providers, and multiple vaccination providers.

CONCLUSIONS

By 24 months of age, 9 of 10 children received at least 1 vaccine outside the recommended age ranges. High vaccination status of children at 24 months of age does not reflect the reality that many vaccinations are not given at the appropriate ages. Timeliness of vaccination is critical to prevent disease outbreaks, protect children through their first 2 years of life, and minimize the need to repeat doses.

The need for surveillance of delay in age-appropriate immunization

BACKGROUND

Vaccination status is assessed nationally in terms of up-to-date status without regard to the age at which recommended doses were actually received. Our study was conducted in 2000-2001 using the most current National Health Interview Survey (NHIS) public use files available.

METHODS

Retrospective analysis to determine up-to-date and age-appropriate vaccination status for children aged 25 to 72 months. Five years of pooled data (1992-1996) were obtained from the NHIS Immunization Supplement for children aged 25 to 72 months with immunization data based on written records. The outcome measures used were months of vaccination delay relative to age-appropriate vaccination standard as well as up-to-date vaccination status for the fourth diphtheria-tetanus-pertussis (DTP 4), Polio3, the first measles-mumps-rubella (MMR1) doses, and the 4:3:1 series.

RESULTS

Of the 9223 eligible children, 80% were up-to-date for the 4:3:1 vaccination series, but 48% had experienced delays relative to age-appropriate standards. For the DTP4 dose, 85% were up-to-date, although only 46% had received this dose at the appropriate age. Similarly, 90% of children were up-to-date with their Polio3 dose, with 64% receiving this dose at the appropriate age; 96% were up-to-date for the MMR1, and 58% received this dose at the appropriate age. Age-appropriate DTP4 vaccination increased by 17 percentage points from 1992 to 1996, whereas up-to-date DTP4 status increased by only 6% during the same period.

CONCLUSIONS

Children with up-to-date vaccination status often experienced considerable delay relative to age-appropriate vaccination standards. Consequently, vaccination status measures based solely on up-to-date status tend to understate the degree of underimmunization in a population. National surveillance of age-appropriate vaccination is necessary to identify subpopulations with the greatest prevalence of vaccination delay and to reveal underlying trends that may not be evident through assessments of up-to-date status.

Changes in vaccination coverage estimates among children aged 19-35 months in the United States, 1996-1999

BACKGROUND

Childhood vaccinations have a major impact on the reduction and elimination of many causes of morbidity and mortality among children. Monitoring of annual vaccination coverage levels over time is necessary to characterize undervaccination. Here, coverage estimates for 1996 (1997 for varicella) were compared with those of 1999.

METHODS

Immunization coverage among children aged 19 to 35 months in 1996 (1997 for varicella) and 1999 for a variety of vaccines and vaccine series were compared using Wald chi-square tests and data from the National Immunization Survey.

RESULTS

Record high immunization coverage among children aged 19 to 35 months in the United States has increased by a statistically significant amount between 1996 and 1999 for diphtheria, tetanus, and pertussis; measles, mumps, and rubella; Haemophilus influenzae type b; hepatitis B; and standard series made up of these individual vaccines. Coverage with the vaccine for varicella dramatically increased between 1997 and 1999. However, between 1996 and 1999, coverage with three or more doses of polio vaccine decreased by a small but statistically significant amount.

CONCLUSION

Despite the drop for polio vaccine, coverage remains high. Continued monitoring is required to determine if the drop in polio coverage is a cause for concern.