Incidence of Bordetella pertussis infection in adolescents and adults.
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Adolescent↗
Biomedical subjects
Andrew L Baughman
Publications and source records attributed to Andrew L Baughman.
Mixture model analysis for establishing a diagnostic cut-off point for pertussis antibody levels.
Previous studies of pertussis (whooping cough) that have derived diagnostic cut-off points for pertussis antibody levels have assumed a single distribution for antibody levels and have used small sample sizes. In a recent study of 5409 serum samples from the Third National Health and Nutrition Examination Survey (NHANES III), a finite mixture model was developed to examine the distribution of immunoglobulin G (IgG) antibody levels against pertussis toxin (PT), an antigen specific to the Bordetella pertussis bacterium. The mixture model identified three component populations with antibody levels greater than the quantitative assay's lower limit of quantitation (LLQ) and included a point distribution located at or below the LLQ to account for the excess number of antibody values that fell below the LLQ. The mixture model analysis accounted for the NHANES III design. A cut-off point for anti-PT IgG levels was chosen to have a 99 per cent model specificity based on the two overlapping normal distributions assumed for the two component populations with the highest antibody levels. This cut-off point may have a higher diagnostic sensitivity for acute B. pertussis infection than other cut-off points derived by assuming a single distribution for antibody levels.
Adolescent↗
Assessment of delay in age-appropriate vaccination using survival analysis.
Assessment of delay in age-appropriate vaccination provides more information about timeliness of vaccination than up-to-date vaccination coverage. The authors applied survival analysis methods to data from a vaccination coverage survey among children aged 13-59 months conducted in Argentina in 2002. By age 19 months, 43% of children (95% confidence interval (CI): 40, 46) were vaccinated with the fourth dose of diphtheria, tetanus, and pertussis (DTP4). By age 13 months, 55% of children (95% CI: 52, 57) were vaccinated with measles-containing vaccine. By age 7 months, 33% of children (95% CI: 27, 40) were vaccinated with the third dose of hepatitis B. Compared with firstborn children, third children were more likely to be delayed for DTP4 (relative risk (RR) = 1.41, 95% CI: 1.22, 1.62), measles-containing vaccine (RR = 1.54, 95% CI: 1.32, 1.78), and the third dose of hepatitis B (RR = 1.31, 95% CI: 1.03, 1.67). Children whose caregivers had completed secondary school were less likely to be delayed for DTP4 (RR = 0.68, 95% CI: 0.52, 0.90) compared with those whose caregivers had not completed primary school. Survival analysis methods were helpful in measuring vaccine uptake and should be considered in future surveys when assessing delay in age-appropriate vaccination.
Age Factors↗
Methods for capture-recapture analysis when cases lack personal identifiers.
Methods for estimating the size of a closed population from a capture-recapture study require the availability of unique identifiers on each of two lists. These identifiers are used to identify the number of individuals appearing on both lists. When the number of individuals appearing on both lists cannot be determined with certainty from the data, matching between the lists is problematic. In this paper, we develop a weighted estimator to account for all possible matches between two lists. A bootstrap procedure is proposed for estimation. To illustrate the methods, we used two lists that recorded New York State (NYS) hospitalizations due to pertussis in 1996 to estimate the number of persons hospitalized for pertussis in NYS that year.
Algorithms↗
Who's calling the shots? Pediatricians' adherence to the 2001-2003 pneumococcal conjugate vaccine-shortage recommendations.
BACKGROUND: A national shortage of heptavalent pneumococcal conjugate vaccine (PCV7) occurred from September 2001 through May 2003. In December 2001 and January 2002, the Advisory Committee on Immunization Practices and the American Academy of Pediatrics (AAP) issued PCV7-shortage recommendations, emphasizing that all health care providers decrease the number of doses for healthy children so that more children could receive some PCV7. OBJECTIVES: We assessed (1) how the PCV7 shortage affected pediatricians, (2) whether children in the public and private sectors were vaccinated differently during the shortage, (3) pediatricians' knowledge of and adherence to the Advisory Committee on Immunization Practices/AAP recommendations, (4) and what factors were associated with nonadherence to the recommendations. METHODS: We conducted a cross-sectional mail survey of 2500 US physician-members of the AAP from November 2002 through March 2003; physicians providing childhood immunizations were eligible. We asked about PCV7-shortage experience, assessed recommendation adherence through clinical scenarios, and modeled potential factors associated with reported nonadherence to the recommendation to defer the fourth PCV7 dose. RESULTS: Of 2478 surveys sent to valid addresses, 1412 (57%) completed surveys were received; 946 (67%) of these were from eligible pediatricians. Overall, 79% experienced a PCV7 shortage, 94% reported being aware of the recommendations, and 42% reported barriers to recommendation adherence. Ninety-four percent reported vaccinating 6-month-old infants with private or public insurance in the same manner. As recommended, 91% reported fully vaccinating high-risk patients. Contrary to recommendations, 49% reported sometimes or always administering the fourth PCV7 dose to healthy children 12 to 15 months old; their reasons included recurrent otitis media, childcare attendance, and parental desire. Controlling for other characteristics, pediatricians who had no PCV7 shortage in their practices were significantly more likely to report administering the fourth dose than pediatricians who had a shortage (odds ratio [OR]: 3.67; 95% confidence interval [CI]: 2.40-5.63). Other factors associated with nonadherence were being in solo private practice (OR: 2.18; 95% CI: 1.26-3.77) or being male (OR: 1.51; 95% CI: 1.08-2.12). Among pediatricians deferring PCV7, 36% reported having no system to track children for whom PCV7 was deferred. CONCLUSIONS: Many pediatricians, both with and without a PCV7 shortage, administered more PCV7 doses than recommended. Pediatricians without a shortage were less likely to limit use, which suggests that they might have focused on the perceived value of administering the full schedule to their patients in preference to broader public health goals. Providing more information to physicians on the effectiveness of a fewer-dose schedule and the risk of disease when vaccine is deferred and educating parents might increase adherence to recommendations and achieve more equitable coverage during vaccine shortages.
Cross-Sectional Studies↗
Vaccination levels associated with lack of measles transmission among preschool-aged populations in the United States, 1989-1991.
Knowledge of the minimum level of vaccination capable of preventing measles transmission in an age group is helpful for establishing program targets for measles elimination. In 1990, during the measles resurgence in the United States, one-half of cases occurred in children aged <5 years. Although estimated population immunity among persons >or=6 years of age was 93%, immunity was lower and varied widely among preschool-aged children. To examine the association of vaccine coverage at 2 years of age and measles incidence among preschool-aged children, we analyzed ecological studies of measles incidence in Milwaukee (Wisconsin) census tracts, Dallas (Texas) ZIP code areas, and selected cities during the 1989-1991 measles resurgence. In each study area, measles incidence decreased rapidly with increasing measles vaccine coverage and became low or negligible when coverage was >or=80%. Regression analysis also suggested that measles would not be transmitted when vaccine coverage was at least 79%. A minimum vaccine coverage of approximately 80% at the second birthday in census tracts, ZIP code areas, and cities in the United States may be sufficient to prevent measles transmission among preschool-aged children if population immunity is >or=93% among persons >or=6 years of age.
Adolescent↗
Establishment of diagnostic cutoff points for levels of serum antibodies to pertussis toxin, filamentous hemagglutinin, and fimbriae in adolescents and adults in the United States.
Numerous reports have documented that serologic methods are much more sensitive than culture for the diagnosis of pertussis in adolescents and adults. However, a standardized serologic test for pertussis is not routinely available to most clinicians, and the serologic test levels or cutoff points correlated with diseases have not been determined. The goal of the present study was to examine the distribution of immunoglobulin G (IgG) levels against three Bordetella pertussis antigens (pertussis toxin [PT], filamentous hemagglutinin [FHA], and fimbria types 2 and 3 [FIM]) and to determine population-based antibody levels for the purpose of establishing such diagnostic cutoff points. Enzyme-linked immunosorbent assays (ELISAs) were performed with sera from >6,000 U.S. residents aged 6 to 49 years who participated in the Third National Health and Nutrition Examination Survey. Mixture models were developed to identify hypothesized exposure groups and establish diagnostic cutoffs. Quantifiable (>20 ELISA units/ml [EU]) anti-FHA and anti-FIM IgG antibodies were common (65 and 62% of individuals, respectively), but quantifiable anti-PT IgG antibodies were less frequent (16%). Given the distributions of antibody levels, an anti-PT IgG level of > or =94 EU was proposed as the diagnostic cutoff point. Application of this cutoff point to culture-confirmed illness in a prior study investigating cough illness yielded a high diagnostic sensitivity (80%) and specificity (93%). A standardized ELISA for anti-PT IgG with a single serum sample appears to be useful for the identification of recent B. pertussis infection in adolescents and adults with cough illness. The PT cutoff point will be further evaluated in prospective studies of confirmed B. pertussis infection.
Adolescent↗
Population immunity to polioviruses among preschool children from four urban underserved low income communities, United States, 1997-2001.
BACKGROUND: In 1997, the Advisory Committee for Immunization Practices (ACIP) recommended a change in polio vaccination policy, the first in 30 years, from the oral poliovirus vaccine (OPV) to a combined OPV/inactivated poliovirus vaccine (IPV) sequential schedule for routine childhood vaccination. To evaluate the impact of the change in polio vaccination schedule on population immunity, we conducted a seroprevalence survey among low income preschool children from selected urban areas. METHODS: A repeat cross-sectional serosurvey was conducted during 1997-2001. Children 19-35 months of age receiving well-child care were recruited from outpatient clinics of academic medical centers. Serum samples were obtained and tested for neutralizing antibodies to polioviruses types 1, 2 and 3. A standardized questionnaire was administered to the parents or guardians of enrolled children. RESULTS: Seroprevalence remained high and stable during the study period. Among children sampled in the last study year (initiating their vaccinations from August 1997 through September 2000), seroprevalence was >/=95% to poliovirus serotypes 1 and 2 and >/=94% to serotype 3. Overall coverage with >/=3 doses of polio vaccine was 82-95% across sites during this period. The proportion initiating their vaccination schedule with IPV increased from 2.6% in study year 1 (children born October 1994-January 1997) to 80% in study year 4 (children born October 1997-January 2000). CONCLUSIONS: Children in these underserved low income communities are well-protected against the spread of polioviruses; the introduction of IPV did not adversely impact coverage or seroprevalence. Continued monitoring is needed to evaluate population immunity in the absence of OPV circulation.
Antibodies, Viral↗
Need for equivalence testing of efficacy of alternative antibiotics for treatment of pertussis.
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Bordetella pertussis↗
Increase in deaths from pertussis among young infants in the United States in the 1990s.
BACKGROUND: Severe pertussis primarily occurs among infants (<12 months of age). Despite high levels of immunization, reported pertussis cases increased in the United States in the 1990s among all age groups, including infants. METHODS: To characterize fatal pertussis cases, we analyzed pertussis deaths reported to CDC in the 1990s and compared these with data on pertussis deaths reported in the 1980s. Data from national surveillance systems and from available medical records were used, including data from analyses of deaths reported in 1992 through 1995. RESULTS: In 1980 through 1989, 77 pertussis deaths were reported; 61 deaths were among infants (1.67 deaths per million), including 49 among infants <4 months of age. In the 1990s 103 pertussis deaths were reported; 93 deaths were among infants (2.40 deaths per million), including 84 among infants <4 months of age. Of 89 infants with ethnicity data, 31 (36%) were Hispanic; the mortality rate among Hispanic infants (4.77 per million) was higher than among non-Hispanic infants (1.80 per million). Of 76 infants with reported gestational age, 40 (53%) were born at <37 weeks, including 22 (29%) who were born at <35 weeks. Severe pulmonary hypertension was a common lethal complication among infants. CONCLUSIONS: Pertussis deaths increased among infants too young to be protected by immunization. A disproportionate share of deaths were complicated by pulmonary hypertension and occurred among Hispanic infants and infants born at <37 weeks gestation. New approaches to prevent infection among infants <4 months of age and improved therapies for pertussis complications are needed.
Adolescent↗
Hepatitis B surface antigen prevalence among pregnant women in urban areas: implications for testing, reporting, and preventing perinatal transmission.
OBJECTIVES: To estimate race/ethnicity-specific prevalence of hepatitis B surface antigen (HBsAg) in pregnant urban women and to evaluate factors associated with maternal HBsAg testing. METHODS: A multicenter, retrospective chart review was conducted of a racially/ethnically stratified random sample of maternal/infant charts of 10 523 women who gave birth to live infants during 1990-1993 in 4 urban areas in the United States. Data were collected on multiple variables, including demographic variables, HBsAg test dates and results, prenatal care type, and amount and source of payment. RESULTS: HBsAg prevalence among white non-Hispanics was 0.60% (95% confidence interval [CI]: 0.22-0.98), black non-Hispanics 0.97% (95% CI: 0.48-1.47), Hispanics 0.14% (95% CI: 0.01-0.26), and Asians 5.79% (95% CI: 4.42-7.16). HBsAg testing rates increased from 56.6% in 1990 to 78.2% in 1993. Factors associated with not being tested varied by urban area, but in the combined area model, they were having no or private prenatal care (odds ratios: 18.75 and 5.07, respectively) and being black (odds ratios: 2.08). Only 20.9% (95% CI: 19.1%-22.8%) of those not tested prenatally were tested at delivery. The expected number of infants born to HBsAg-positive study-area women was 3327 using study prevalence rates, compared with 1761 using national rates. CONCLUSIONS: To help ensure that all urban infants who are born to HBsAg-positive women receive appropriate prophylaxis, health officials in urban areas should use urban-area prevalence rates to ascertain completeness of reporting maternal HBsAg positivity. Needed steps to increase maternal HBsAg testing rates include ensuring that more pregnant women receive prenatal care, promoting testing by private providers, educating providers about testing in all racial and ethnic groups, and reminding providers to test at delivery those women not tested prenatally.
Birth Certificates↗
Outbreak of varicella at a day-care center despite vaccination.
BACKGROUND: In seven studies of the effectiveness of the varicella vaccine conducted since it was licensed, the effectiveness was 71 to 100 percent against disease of any severity and 95 to 100 percent against moderate and severe disease. We investigated an outbreak of varicella in a population of children with a high proportion of vaccinees who were attending a day-care center in a small community in New Hampshire. METHODS: Using standardized questionnaires, we collected information about the children's medical and vaccination history from parents and health care providers. The analysis of the effectiveness of the vaccine and of risk factors for vaccine failure was restricted to children who were enrolled in the day-care center continuously during the outbreak and attended for one week or more and who were cared for in the building that represented the epicenter of the outbreak, since transmission was not documented in a second building. RESULTS: Varicella developed in 25 of 88 children (28.4 percent) between December 1, 2000, and January 11, 2001. The index case occurred in a healthy child who had been vaccinated three years previously and who infected more than 50 percent of his classmates who had no history of varicella. The effectiveness of the vaccine was 44.0 percent (95 percent confidence interval, 6.9 to 66.3 percent) against disease of any severity and 86.0 percent (95 percent confidence interval, 38.7 to 96.8 percent) against moderate or severe disease. Children who had been vaccinated three years or more before the outbreak were at greater risk for vaccine failure than those who had been vaccinated more recently (relative risk, 2.6 [95 percent confidence interval, 1.3 to 5.3]). CONCLUSIONS: In this outbreak, vaccination provided poor protection against varicella, although there was good protection against moderate or severe disease. A longer interval since vaccination was associated with an increased risk of vaccine failure. Breakthrough infections in vaccinated, healthy persons can be as infectious as varicella in unvaccinated persons.
Antibodies, Viral↗
Tracking varicella deaths: accuracy and completeness of death certificates and hospital discharge records, New York State, 1989-1995.
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Adolescent↗