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Biomedical subjects

Susan Y Chu

Publications and source records attributed to Susan Y Chu.

At least 19 recordsLinked to original sources

The United States pediatric vaccine stockpile program.

The initial goal of the national vaccine stockpile program was to establish a 6-month supply of all recommended childhood vaccines, to meet national demands if a manufacturing process was interrupted. When the first vaccine stockpiles were created in 1983, the childhood immunization schedule was much less complicated than it is today, and the first stockpiles included only measles-mumps-rubella, poliovirus, and pertussis vaccines, as well as diphtheria and tetanus toxoids. However, today's vaccine needs are much greater, and current stockpiles do not include all recommended childhood vaccines, partially because inclusion of vaccines that are universally recommended, fully implemented, and produced by a single manufacturer has been made a priority. Future planning must also consider substantially higher vaccine costs, the development of new combination vaccines, a wide range of production times, and changes in immunization recommendations. Expansion and strengthening of the national vaccine stockpile program are critical to protect against future disruptions in vaccine supply.

Centers for Disease Control and Prevention, U.S.↗

Racial and ethnic disparities in influenza vaccination coverage among adults during the 2004-2005 season.

During the 2004-2005 influenza season, the supply of vaccine to the United States was significantly reduced. In response, the Centers for Disease Control and Prevention and the Advisory Committee on Immunization Practices issued interim recommendations for prioritizing vaccination. Given trends in racial/ethnic disparities in vaccination for influenza, the authors assessed the impact of the shortage on those historically less likely to be vaccinated. Using data from the Behavioral Risk Factor Surveillance System, they considered vaccination coverage among those non-Hispanic Whites, non-Hispanic Blacks, and Hispanics who had priority for being vaccinated during the 2004-2005 influenza season. The vaccine shortage had a significant negative effect on coverage among adults aged 65 years or older across the three racial/ethnic groups. Yet, the magnitude of the disparities in coverage did not change significantly from previous seasons. This finding may imply similar patterns of vaccine-seeking behavior during shortage and nonshortage years. No racial/ethnic differences were seen among adults aged 18-64 years, which likely reflects the higher percentage of health-care workers in this age group. Yearly monitoring of influenza vaccine coverage is important to assess the long-term impact of shortages on overall coverage and gaps in coverage between racial/ethnic groups.

Adult↗

Associations between childhood vaccination coverage, insurance type, and breaks in health insurance coverage.

OBJECTIVES: This study explored how vaccination coverage is associated with not being insured and with insurance type among children who are insured and to show how these associations are modified by race/ethnicity. METHODS: We determined whether 8324 children sampled in the National Immunization Survey in 2001 and 2002 were covered by private insurance only, Medicaid/State Children's Health Insurance Program, or another insurance type or were uninsured at the time of the National Immunization Survey interview or were uninsured at some time before the interview. Children were up to date if, by the date of the interview, their vaccination providers had administered > or =4 doses of diphtheria-tetanus toxoids-acellular pertussis vaccine, > or =3 doses of polio vaccine, > or =1 dose of measles-mumps-rubella vaccine, > or =3 doses of Haemophilus influenzae type b vaccine, and > or =3 doses of hepatitis B vaccine. To evaluate the association between insurance type and breaks in insurance with timely completion of the recommended vaccination schedule soon after 19 months of age, we restricted our analyses to children 19 to 24 months of age. RESULTS: Nationally, 12.6 +/- 1.6% of all children 19 to 24 months of age were uninsured at some time. Children who were uninsured at the time of the National Immunization Survey interview had significantly lower vaccination coverage than did children with Medicaid/State Children's Health Insurance Program coverage or children with private insurance only (52.6% vs 70.0% and 75.6%). Children who had never been insured and children who were insured but had a break in insurance coverage in the 12 months immediately preceding the National Immunization Survey interview had significantly lower vaccination coverage than did children who had been insured continuously (47.4% and 64.8% vs 73.5%). CONCLUSIONS: Approximately 1 of 8 children were uninsured at some time, and those children were at greater risk of not being vaccinated on time as recommended.

Black or African American↗

Disparities between white and African-American children in immunization coverage.

INTRODUCTION: A recent study has shown that the national-scale difference in immunization coverage between non-Hispanic white (abbreviated "white") and non-Hispanic African-American (abbreviated "African-American") children aged 19-35 months in the United States has increased by about 1 percentage point annually. We examined how this widening gap differs with geography and income. METHODS: We used data from the National Immunization Survey, 1998-2003, a national telephone survey. We examined differences between white and African-American children in immunization coverage within income groups (at or above versus below the federal poverty level) for each census region (northeast, south, midwest and west). We tested the hypothesis of constant disparity over time. RESULTS: Among households at or above the federal poverty level in the northeast census region, disparity is widening (white coverage minus African-American coverage was -0.5 in 1998 but 15.5 in 2003). Among household at or above the federal poverty level in the midwest census region, disparity is narrowing (white coverage minus African-American coverage was 13.9 in 1998 but 2.5 in 2003). We found no significant evidence of a trend in other groups. CONCLUSIONS: Widening national-level disparity in immunization coverage is primarily attributable to trends in the northeast census region. Addressing the widening disparity in coverage requires new strategies that consider current social and economic contexts.

Black or African American↗

Economic evaluation of the 7-vaccine routine childhood immunization schedule in the United States, 2001.

OBJECTIVE: To evaluate the economic impact of the routine US childhood immunization schedule: diphtheria and tetanus toxoids and acellular pertussis; tetanus and diphtheria toxoids; Haemophilus influenzae type b conjugate; inactivated poliovirus; measles, mumps, and rubella; hepatitis B; and varicella vaccines. DESIGN: Decision tree-based analysis was conducted using population-based vaccination coverage, published vaccine efficacies, historical data on disease incidence before vaccination, and disease incidence reported for 1995-2001. Costs were estimated using the direct cost and societal (direct and indirect costs) perspectives. Program costs included vaccine, administration, vaccine-associated adverse events, and parent travel and time lost. All costs were inflated to 2001 US dollars, and all costs and benefits in the future were discounted at a 3% annual rate. PARTICIPANTS: A hypothetical 2001 US birth cohort of 3,803,295 infants was followed up from birth through death. MAIN OUTCOME MEASURES: Net present value (net savings) and benefit-cost ratios of routine immunization. RESULTS: Routine childhood immunization with the 7 vaccines was cost saving from the direct cost and societal perspectives, with net savings of 9.9 billion dollars and 43.3 billion dollars, respectively. Without routine vaccination, direct and societal costs of diphtheria, tetanus, pertussis, H influenzae type b, poliomyelitis, measles, mumps, rubella, congenital rubella syndrome, hepatitis B, and varicella would be 12.3 billion dollars and 46.6 billion dollars, respectively. Direct and societal costs for the vaccination program were an estimated 2.3 billion dollars and 2.8 billion dollars, respectively. Direct and societal benefit-cost ratios for routine childhood vaccination were 5.3 and 16.5, respectively. CONCLUSION: Regardless of the perspective, the current routine childhood immunization schedule results in substantial cost savings.

Chickenpox↗

Immunization coverage among Hispanic ancestry, 2003 National Immunization Survey.

BACKGROUND: The Hispanic population is increasing and heterogeneous (Hispanic refers to persons of Spanish, Hispanic, or Latino descent). The objective was to examine immunization rates among Hispanic ancestry for the 4:3:1:3:3 series (> or = 4 doses diphtheria, tetanus toxoids, and pertussis vaccine; > or = 3 doses poliovirus vaccine; > or = 1 doses measles-containing vaccine; > or = 3 doses Haemophilus influenzae type b vaccine; and > or = 3 doses hepatitis B vaccine). METHODS: The National Immunization Survey measures immunization coverage among 19- to 35-month-old U.S. children. Coverage was compared from combined 2001-2003 data among Hispanics and non-Hispanic whites using t-tests, and among Hispanic ancestry using a chi-square test. Hispanics were categorized as Mexican, Mexican American, Central American, South American, Puerto Rican, Cuban, Spanish Caribbean (primarily Dominican Republic), other, and multiple ancestry. RESULTS: Children of Hispanic ancestry increased from 21% in 1999 to 25% in 2003. These Hispanic children were less well immunized than non-Hispanic whites (77.0%, +/-2.1% [95% confidence interval] compared to 82.5%, +/-1.1% (95% CI) > in 2003). Immunization coverage did not vary significantly among Hispanics of varying ancestries (p=0.26); however, there was substantial geographic variability. In some areas, immunization coverage among Hispanics was significantly higher than non-Hispanic whites. CONCLUSIONS: Hispanic children were less well immunized than non-Hispanic whites; however, coverage varied notably by geographic area. Although a chi-square test found no significant differences in coverage among Hispanic ancestries, the range of coverage, 79.2%, +/-5.1% for Cuban Americans to 72.1%, +/-2.4% for Mexican descent, may suggest a need for improved and more localized monitoring among Hispanic communities.

Child, Preschool↗

The association between having a medical home and vaccination coverage among children eligible for the vaccines for children program.

BACKGROUND: The Vaccines for Children (VFC) program is designed to reduce the cost of vaccines for vulnerable children, including Medicaid-eligible children, American Indian/Alaska Native children, uninsured children, and underinsured children whose health insurance does not cover the cost of vaccinations. A desired consequence of the program is to promote comprehensive continuous medical care within a medical home for these children. OBJECTIVES: To explore how having a medical home is associated with vaccination coverage among children eligible for the program. PARTICIPANTS: A total of 24514 children 19 to 35 months of age sampled by the National Immunization Survey. DESIGN: VFC eligibility was evaluated for 24514 children 19 to 35 months of age who were sampled by the National Immunization Survey. Children were considered to have a medical home if they had a doctor, nurse, or physician's assistant who provided them with ongoing routine care, including well-child care, preventive care, and sick care, according to their parents. Sampled children were determined to be 4:3:1:3:3 up-to-date (UTD) if their vaccination providers reported administering >or=4 doses of diphtheria-tetanus toxoids-acellular pertussis vaccine, >or=3 doses of polio vaccine, >or=1 dose of measles-mumps-rubella vaccine, >or=3 doses of Haemophilus influenzae type b vaccine, and >or=3 doses of hepatitis B vaccine. RESULTS: Nationally, 44.9% of all children were VFC eligible and 93.0% of the VFC-eligible children received all vaccine doses at a provider enrolled in the VFC program. Compared with children who were not VFC eligible, VFC-eligible children were less likely to be UTD (70.8% vs 77.7%) and less likely to have a medical home (82.1% vs 95.0%). However, among VFC-eligible children, children who had a medical home were significantly more likely to be UTD, compared with children who did not have a medical home (72.3% vs 63.5%). Also, among VFC-eligible children who had a medical home, children who used their medical home consistently to receive all of their vaccination doses were significantly more likely to be UTD, compared with children who did not receive all of their doses from their medical home (75.3% vs 65.7%). Finally, the 4:3:1:3:3 vaccination coverage rate among VFC-eligible children who received all of their vaccination doses from their medical home was not significantly different from that among non-VFC-eligible children, after controlling for significant differences in sociodemographic factors between these groups (adjusted difference: 2.8%; 95% confidence interval: -0.1% to 5.7%). CONCLUSIONS: Although the vaccination coverage rate among VFC-eligible children who had a medical home and received all vaccine doses from their medical home was essentially equivalent to that of non-VFC-eligible children, substantial percentages of VFC-eligible children either did not have a medical home or did not use their medical home to receive all of their recommended vaccinations. The vaccination coverage rate among these children was significantly lower. This suggests that there may be opportunities to increase vaccination coverage by removing barriers that prevent the adoption and consistent use of a medical home among these children.

Child Health Services↗

Tetanus and diphtheria immunity among females in the United States: are recommendations being followed?

OBJECTIVE: The purpose of this study was to examine prevalence and factors associated with tetanus and diphtheria immunity among women in the United States. STUDY DESIGN: Sera from 9411 female participants from the third National Health and Nutrition Examination Survey were tested for diphtheria and tetanus antitoxin. Interview information for adult women was analyzed to examine associations with immunity. RESULTS: Fifty-seven percent of the female subjects who were > or =6 years old were positive for diphtheria, and 64% of the female subjects for tetanus anti-toxin. Among women > or =20 years old, only 41% of the women were protected against both antigens. Older age, birth outside the United States, and less education was associated with lower immunity. Markers for contact with the health care system were not related to higher immunity. CONCLUSION: More than one half of US women > or =20 years old who were tested were not protected fully against diphtheria and tetanus. All physicians, including obstetricians and gynecologists who may be the sole medical providers for women, should be familiar with the current Advisory Committee on Immunization Practices recommendations regarding tetanus and diphtheria toxoid booster vaccines.

Adolescent↗

Children who have received no vaccines: who are they and where do they live?

CONTEXT: Each year 2.1 million children 19 to 35 months of age are undervaccinated. Among these are children who have received no vaccinations. Unvaccinated children are at increased risk of acquiring and transmitting vaccine-preventable diseases. OBJECTIVES: To assess whether the characteristics of children with no vaccinations differ from those of undervaccinated children, to monitor trends in the numbers of unvaccinated children, and to identify states with high rates and counties with large numbers of unvaccinated children. DESIGN: A nationally representative probability sample of children 19 to 35 months of age was collected annually between 1995 and 2001. Vaccination histories were ascertained from children's medical providers. Undervaccinated children had received > or =1 dose of diphtheria-tetanus-pertussis, polio, measles, Haemophilus influenzae type b, hepatitis B, or varicella vaccine but were not fully vaccinated. Unvaccinated children were children who were reported as having no medical providers and having received no vaccinations or children whose medical providers reported administering no vaccinations. PARTICIPANTS: A total of 151,720 children sampled between 1995 and 2001, 795 of whom were unvaccinated. RESULTS: Undervaccinated children tended to be black, to have a younger mother who was not married and did not have a college degree, to live in a household near the poverty level, and to live in a central city. Unvaccinated children tended to be white, to have a mother who was married and had a college degree, to live in a household with an annual income exceeding 75,000 dollars, and to have parents who expressed concerns regarding the safety of vaccines and indicated that medical doctors have little influence over vaccination decisions for their children. Unvaccinated children were more likely to be male than female. Annually, approximately 17,000 children were unvaccinated. The largest numbers of unvaccinated children lived in counties in California, Illinois, New York, Washington, Pennsylvania, Texas, Oklahoma, Colorado, Utah, and Michigan. States that allowed philosophical exemptions to laws mandating vaccinations for children as they entered school had significantly higher estimated rates of unvaccinated children. CONCLUSIONS: Unvaccinated children have characteristics that are distinctly different from those of undervaccinated children. Unvaccinated children are clustered geographically, increasing the risk of transmitting vaccine-preventable diseases to both unvaccinated and undervaccinated children.

Attitude to Health↗

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.

Child, Preschool↗

Comparison of e-mail, fax, and postal surveys of pediatricians.

OBJECTIVES: To compare 3 communication modes (postal, fax, and e-mail) in a rotavirus vaccine physician survey. METHODS: We used 3 communication modes to distribute a survey to physicians listed in the membership directory of the Georgia Chapter of the American Academy of Pediatrics. The directory listed 1391 members; however, 404 were deemed ineligible on the basis of their listing as a specialist, retiree, resident in training, or government public health employee. Of the 987 members expected to administer vaccines, 150 were selected randomly to receive the postal survey (postal group). Of the remaining listings, 488 (58%) of 837 listed a fax number; 150 members were selected randomly and faxed a survey (fax group). Of the remaining members, 266 (39%) of 687 had e-mail addresses listed; 150 members were selected randomly for the e-mail survey (e-mail group). A follow-up survey was sent by the same mode at 2 weeks. A final survey was sent via another mode (mixed mode) at 1 month: by fax to e-mail and postal nonresponders and by post to fax nonresponders and those without fax. RESULTS: Eligible respondents in the 3 survey groups were similar in their practice setting and location. Although the e-mail group had fewer median years (8 years) since medical school graduation than the fax group (19 years) and postal group (17 years), a similar percentage of responders in all groups had computers (>85%) and Internet access (> or =70%) at work. However, only 39% of members listed an e-mail address in the directory. In the 2 weeks after the first mailing, 39 surveys were completed via postal mail, 50 via fax, and 16 via e-mail. In the 2 weeks after the second contact (sent at 2 weeks), 20 surveys were completed via postal mail, 15 via fax, and 17 via e-mail. The response rate after the first 2 mailings was 41% (59 of 143) for postal, 47% (65 of 137) for fax, and 26% (33 of 125) for e-mail surveys. The third and final survey (sent 1 month after the first mailing) was sent by a different (ie, mixed) mode and elicited an additional 73 responses: 19 responses (15 postal, 4 fax) from the postal group, 19 responses (18 postal, 1 fax) from the fax group, and 35 responses (15 postal, 13 fax, 7 e-mail) from the e-mail group. Twenty-three percent (9 of 40) of the e-mail and 18% (15 of 83) of the fax surveys completed were returned on the same or subsequent day they were sent, compared with none of the postal surveys. There were significant differences among the 3 groups for invalid addresses/numbers (4% postal, 8% fax, and 16% e-mail) listed in the directory. Using mixed modes as the third contact, the overall response rate increased from 39% before mixed mode to a final of 53%. On the basis of the 3 initial groups, responses to 1 of 12 rotavirus questions differed significantly. CONCLUSIONS: Future use of e-mail surveys in selected circumstances is promising, because the majority of providers have Internet access and acknowledged interest in participating in e-mail surveys. E-mail surveys could be especially useful if rapid response time is necessary. There were fewer incomplete questions by participants who completed the e-mail survey compared with postal or fax participants. Updating membership e-mail addresses and routinely using e-mail as a communication tool should improve the ability to use e-mail surveys. There may need to be ongoing evaluations that critically evaluate providers' responses to e-mail surveys compared with other survey modes before e-mail surveys can become a standard survey tool. In the meantime, mixed-mode surveys may be an option.

Cross-Sectional Studies↗

A survey of pediatricians on the reintroduction of a rotavirus vaccine.

OBJECTIVE: Rhesus-based rotavirus tetravalent vaccine (RRV-TV; RotaShield) was withdrawn voluntarily from the market in October 1999, and recommendations for use were suspended. Rotavirus infection continues to be a significant health problem affecting children worldwide. The objective of this study was to investigate whether pediatricians would either reconsider using RRV-TV or consider other, newer, and presumably safer rotavirus vaccines if they were recommended routinely and to determine factors that influence their opinion. METHODS: A questionnaire was sent to a random sample of 250 members of the Wisconsin Chapter of the American Academy of Pediatrics (AAP) and to 437 randomly selected members of the Georgia Chapter of the AAP. Nonresponders received reminder questionnaires. RESULTS: Of the 687 pediatricians surveyed, 384 (56%) responded. Responses from 319 eligible immunization providers were included in the final analysis. Although only 15% of respondents reported that they would give RRV-TV if it were available today, 94% reported that they would use a new rotavirus vaccine if proved to be safer than RRV-TV and if recommended by the AAP and Advisory Committee on Immunization Practices for routine use among infants. Barriers to reintroducing a rotavirus vaccine were fear of adverse reactions among 95% of pediatricians, followed by potential high vaccine cost (63%) and amount of time required to educate parents (57%). CONCLUSIONS: Pediatricians reported that they would use a rotavirus vaccine if it was safer than RRV-TV and routinely recommended by the AAP and the Advisory Committee on Immunization Practices.

Adult↗

Maternal characteristics associated with vaccination of young children.

OBJECTIVE: Mothers can be instrumental in gaining access to vaccination services for their children. This study examines maternal characteristics associated with vaccination in US preschool children. METHODS: We analyzed data from 21 212 children aged 19 to 35 months in the National Immunization Survey. Bivariate and multivariate analyses were used to identify maternal characteristics associated with completion of all recommended vaccinations in these children. RESULTS: Factors most strongly associated with undervaccination included having mothers who were black; had less than a high school education; were divorced, separated, or widowed; had multiple children; were eligible for the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) but not participating; or had incomes below 50% of the federal poverty level. CONCLUSION: Because most mothers play an important role in their children's vaccination, it is important to address maternal concerns and barriers when developing public health interventions for promoting childhood vaccinations. Encouraging eligible women and their children to participate in the WIC program and providing support and encouragement for immunization to mothers with multiple children may improve early childhood vaccination coverage.

Adolescent↗

Assessing equivalence: an alternative to the use of difference tests for measuring disparities in vaccination coverage.

Eliminating health disparities in vaccination coverage among various groups is a cornerstone of public health policy. However, the statistical tests traditionally used cannot prove that a state of no difference between groups exists. Instead of asking, "Has a disparity--or difference--in immunization coverage among population groups been eliminated ?," one can ask, "Has practical equivalence been achieved?" A method called equivalence testing can show that the difference between groups is smaller than a tolerably small amount. This paper demonstrates the method and introduces public health considerations that have an impact on defining tolerable levels of difference. Using data from the 2000 National Immunization Survey, the authors tested for statistically significant differences in rates of vaccination coverage between Whites and members of other racial/ethnic groups and for equivalencies among Whites and these same groups. For some minority groups and some vaccines, coverage was statistically significantly lower than was seen among Whites; however, for some of these groups and vaccines, equivalence testing revealed practical equivalence. To use equivalence testing to assess whether a disparity remains a threat to public health, researchers must understand when to use the method, how to establish assumptions about tolerably small differences, and how to interpret the test results.

Child, Preschool↗

Serologic immunity to diphtheria and tetanus in the United States.

BACKGROUND: Serologic data on diseases that are preventable by vaccine are useful to evaluate the success of immunization programs and to identify susceptible subgroups. OBJECTIVE: To provide national estimates of immunity to diphtheria and tetanus by measurement of serum antibody levels. DESIGN: Examination of data from the Third National Health and Nutrition Examination Survey, a representative cross-sectional sample of the U.S. population. SETTING: 89 randomly selected locations throughout the United States. PARTICIPANTS: 18 045 persons 6 years of age or older who were examined from 1988 to 1994. MEASUREMENTS: Serum samples obtained at a single time point were tested for diphtheria and tetanus antitoxin. RESULTS: Overall, 60.5% of Americans 6 years of age or older had fully protective levels of diphtheria antibody (> or =0.10 IU/mL) and 72.3% had protective levels of tetanus antibody (> 0.15 IU/mL). Ninety-one percent of Americans 6 to 11 years of age had protective levels of both diphtheria and tetanus antibody; this proportion decreased to approximately 30% among persons 70 years of age (29.5% for diphtheria and 31.0% for tetanus). Adult Mexican-Americans were slightly less likely to have protective levels of antibody to both toxins. Only 47% of persons 20 years of age or older had levels that were protective against both diseases, and only 63% of adults who were protected against tetanus were also protected against diphtheria. CONCLUSIONS: A substantial proportion of adults in the United States do not have antibody levels that are protective against diphtheria and tetanus. In addition, although the recommended vaccine is a combination of tetanus and diphtheria, only 63% of adults with protective antibody to tetanus also had protective antibody to diphtheria.

Adolescent↗