Effects of traditional classroom and distance continuing education: a theory-driven evaluation of a vaccine-preventable diseases course.

OBJECTIVES: This study evaluated the effects of a major federal immunization continuing education course, delivered in both traditional classroom and satellite broadcast versions, on public health professionals' knowledge, agreement, self-efficacy, and adherence in practice to recommendations. METHODS: The study used a comparative time series design to determine whether the course influenced participants' knowledge, agreement, self-efficacy, and adherence in practice to general and polio-specific recommendations as measured immediately and 3 months after the course. It also compared the effects of the classroom and satellite broadcast versions and used path analysis to show how the outcomes were related to one another. RESULTS: Both versions significantly improved knowledge, agreement, self-efficacy, and adherence. Knowledge and agreement were significant predictors of self-efficacy, which directly predicted adherence. Vaccine availability and supportive clinic policies were also important adherence predictors. CONCLUSIONS: A well-designed training update can change provider knowledge, agreement, self-efficacy, and adherence. Traditional classroom and distance training can have comparable effects. The findings support incorporation of distance learning in national public health training, if the distance learning is used wisely in relation to training needs, goals, and practice contexts.

Decline of measles-specific immunoglobulin M antibodies after primary measles, mumps, and rubella vaccination.

Detection of measles-specific immunoglobulin M (IgM) has become the standard diagnostic method for laboratory confirmation of measles. In outbreaks, the interpretation of an IgM-positive result can be complicated when persons with suspected measles receive a dose of measles vaccine as part of outbreak control measures. This investigation evaluated the decay of measles-specific IgM antibodies 1 to 4 months after primary vaccination with measles, mumps, and rubella vaccine (MMRII). Serum samples were obtained from 536 infants vaccinated when they were 15 months old as part of a study to assess primary and secondary measles vaccine failure. Sixty serum specimens per week were selected from specimens collected between 4 and 9 weeks after MMRII vaccination; all 176 available serum specimens collected between 10 and > or = 16 weeks were included. Specimens were tested for the presence of measles-specific IgM by an antibody-capture enzyme immunoassay. The proportion of IgM-positive specimens dropped from 73% at 4 weeks after vaccination to 52% at 5 weeks after vaccination and then declined to 7% by 8 weeks after vaccination. Less than 10% of children remained IgM positive between 9 and 11 weeks. An IgM-negative result helps rule out the diagnosis of measles in a person with suspected infection and a history of recent vaccination. The interpretation of a positive IgM result from a person with a clinically suspected case of measles and a recent history of measles vaccination (especially within 8 weeks) is problematic, and the diagnosis of measles should be based on epidemiologic linkage to a confirmed case or on detection of wild-type measles virus.

Association of livebirths and the resurgence of measles.

BACKGROUND: The basis for the resurgence of measles in the US in 1989 and 1990 is not understood. This analysis was undertaken to test the hypothesis that an increase in the number of livebirths was associated with the resurgence of measles in the US. METHODS: We undertook an ecologic analysis of 20 cities/countries in the US with documented rates of immunization among 2-year-old children. RESULTS: Over the 6-year period 1985-1990, the numbers of livebirths and of susceptible preschool aged children increased by 18.5% and 17.7%, respectively. Livebirths, and the number and density of susceptible preschool-age children were significantly associated with the number and incidence of measles among preschool children (r = 0.83, P = 0.04). In a comparison between counties, numbers of livebirths were also significantly correlated with the mean number (r = 0.73, P = 0.0003) and incidence of measles cases (r = 0.51, P = 0.02). Mean immunization rates of 2-year-old children were also associated with the mean incidence of measles (r = -0.66, P = 0.0015, and r = -0.57, P = 0.009, respectively). In a logistic regression model, levels of immunization and susceptible density were independent predictors of measles epidemics among preschool children. CONCLUSIONS: These data suggest that the increase in livebirths, leading to an increase in the number and density of susceptible hosts, was associated with the resurgence of measles among preschool-age children.

Measles vaccine effectiveness and duration of vaccine-induced immunity in the absence of boosting from exposure to measles virus.

BACKGROUND: It is unknown whether vaccine-induced immunity is lifelong in the absence of periodic exposure to measles virus. After 27 years of no known exposure to measles, an outbreak in Palau in 1993 offered the opportunity to study this issue and the measles vaccine effectiveness. METHODS: Household contacts of a sample of confirmed cases were interviewed for exposure, symptoms and vaccination status verified by records. Serum from symptomatic contacts was tested for measles antibodies. RESULTS: Among 78 contacts 4 of 5 (80%) unvaccinated, 4 of 35 (11%) 1-dose vaccine recipients and none of 38 (0%) > 1-dose recipients developed measles. Effectiveness of 1-dose vaccine was 86% (95% confidence interval, 60 to 95%). An additional dose significantly reduced the risk of measles (P = 0.048). Time since vaccination was not a significant risk factor for developing measles (relative risk, 1.6; 95% confidence interval, 0.3 to 9.4; persons vaccinated > 15 years ago vs. < 5 years ago). CONCLUSIONS: Similar to the estimates previously obtained in the area, measles vaccine effectiveness in Palau was lower than the estimates obtained in the US. A second dose of vaccine further reduced the risk for developing measles. We found no evidence that waning immunity was an important problem in this limited population with no known previous exposure to measles virus. The small number of vaccinated contacts precludes a definitive assessment.

Use of Texas birth certificate data to predict measles immunization status.

Inadequate immunization has been a major cause of epidemic measles, but risk factors for inadequate immunization are poorly characterized. By using measles data bases and computerized birth certificate files, we identified a retrospective cohort of 1,070 Texas-born children who were aged 15 months to 10 years when they had measles during the 1988 to 1991 epidemics. We used measles and birth certificate data, including prenatal care and demographic information, to determine immunization status and risk factors for inadequate measles immunization. Risk factors predicting lack of immunization in children with measles in stepwise logistic regression were black ethnicity, urban residence, poor prenatal care, preschool age, and an unknown father. Birth certificates contain information that can predict inadequate measles vaccination and should be evaluated prospectively.

Epidemiology and prevention of measles.

Measles is a highly contagious viral illness which once affected more than 95% of persons in the United States. Since licensure of a safe and highly effective vaccine, measles incidence has fallen to less than 1% of prevaccination levels. A relative resurgence of measles during 1989-1991, however, focused attention on the need to maintain high immunization levels, particularly among preschool-aged children in urban areas. Improved vaccine coverage levels and a second-dose strategy to eliminate susceptibilities resulting from vaccine failure can help achieve the goal of elimination of indigenous measles from the United States by 1996.

High incidence of congenital rubella syndrome after a rubella outbreak.

Previous studies of the incidence of congenital rubella syndrome (CRS) after rubella outbreaks have been limited because most women with infection during the first trimester elected to have their pregnancies terminated. After a rubella outbreak in 1991 we measured prospectively the impact of maternal infection on CRS among the Amish in one county in Pennsylvania. We compared rubella serology of Amish women delivering before and after the outbreak and cord blood rubella IgM from Amish and non-Amish infants. Before the outbreak 20% of Amish women were susceptible to rubella; after the outbreak 4% were (P = 0.001). Of Amish infants 15% tested positive for rubella IgM; no non-Amish infants did (P < 0.001). This rubella outbreak in a largely unimmunized community led to a high rate of CRS. The annual CRS rate among the Amish was 2130/100,000 live births. Health care providers should promote immunization in all clients and intensify efforts among the Amish.

The impact of college prematriculation immunization requirements on risk for measles outbreaks.

OBJECTIVE: To assess whether prematriculation immunization requirements (PIRs) affect the number of measles cases on college campuses. DESIGN: We surveyed a stratified random sample of 880 colleges and universities to determine their immunization policies and practices and occurrence of measles outbreaks from 1988 through 1991. We merged national measles surveillance data with survey data by county to determine the risk for measles introduction on college campuses. We used logistic regression methods to estimate the effect of PIRs and assess risk factors for college measles outbreaks. SETTING: A total of 3205 US colleges and universities listed in standard guides. RESULTS: Of selected schools, 91 (11%) of the 796 responding schools reported one or more measles cases occurring from 1988 through 1991. Schools with a state-mandated PIR were significantly less likely to report measles outbreaks of two or more cases than other institutions (adjusted relative risk [RR] = 0.30; 95% confidence interval [Cl], 0.11 to 0.84). None of the 14 schools that reported outbreaks of 10 or more cases was subject to state regulation or had a PIR specifying two doses of measles vaccine in place. Of schools with introduction of measles, residential colleges were more likely to report extensive spread of measles (five or more cases) than nonresidential colleges (RR = 35.8; 95% Cl, 2.08 to 617.0). Of public schools, 4-year programs had a higher risk of a large outbreak (five or more cases) than 2-year programs. CONCLUSIONS: These results strongly support current recommendations for requiring proof of vaccination of college students to decrease the risk for measles outbreaks on college campuses. State regulations mandating PIRs ensure the best protection against widespread measles transmission.

Worldwide measles prevention.

Prior to measles vaccine use, measles accounted for over 2.5 million deaths annually. Measles epidemiology in the developed countries is different from that in less developed countries. Whereas in the developing world, measles is a disease primarily of young children, particularly infants in urban areas, in the developed world, school-age children > 5 years old play a greater role. Prevention of measles in developing countries has relied principally on a single dose of Schwarz strain vaccine at age 9 months (> 85% efficacy); 80% coverage has prevented > 1.6 million deaths. However, problems have been encountered because of the narrow window to deliver vaccines between the time an infant becomes susceptible and exposure to disease. Recent studies suggest that some strains of measles vaccines given at potencies 10-100 times higher than standard vaccines may achieve good efficacy in infants aged 4-6 months, but safety of these vaccines has been questioned. Widespread use of standard vaccines in the West has resulted in dramatic reductions in measles incidence but has not prevented outbreaks among the 2-5% of persons not protected by a single dose. Such outbreaks often appear after extended periods either without measles or with low measles incidence. A single dose appears adequate to control measles well but inadequate to eliminate the disease. Many developed countries have adopted two-dose schedules. Measles immunization has dramatically reduced measles occurrence, but improved control is necessary to prevent the estimated 1 million deaths still occurring each year.

Measles vaccination in pediatric emergency departments during a measles outbreak.

OBJECTIVE: To determine the proportion of preschool-aged patients attending two inner-city hospital pediatric emergency departments (EDs) who were eligible for measles vaccination, to describe their demographic and clinical characteristics, and to assess the performance of the ED immunization programs that were implemented during a measles outbreak in vaccinating eligible children. DESIGN: Cross-sectional study. SETTING: Pediatric EDs of two urban hospitals in Chicago, Ill, in 1989. PARTICIPANTS: Children 6 months to 5 years of age seen in the EDs. INTERVENTION: None. MAIN OUTCOME MEASURES: The proportion of preschool-aged patients attending the two EDs who were eligible for measles vaccination and the proportion of vaccine-eligible children who were given measles vaccine. RESULTS: Of 508 ED patients at hospital A and 255 patients at hospital B, 18% and 29%, respectively, were considered to be vaccine eligible. The most common discharge diagnoses of eligible patients were viral syndrome, otitis media, and minor trauma. Of vaccine-eligible patients, 59% at hospitals A and B were not vaccinated in the ED. At hospital B, patients with an infectious or respiratory disease diagnosis were less likely to be vaccinated than those with other diagnoses (P < .05). CONCLUSIONS: Many children seen in these EDs were eligible for measles vaccination, and many eligible patients were not vaccinated. During community outbreaks of measles, optimal vaccination programs in pediatric EDs could increase vaccination coverage among inner-city preschool-aged children who may have limited access to health care.

Reporting efficiency during a measles outbreak in New York City, 1991.

OBJECTIVES: During an epidemic of measles among preschool children in New York City, an investigation was conducted in 12 city hospitals to estimate reporting efficiency of measles to the New York City Department of Health. METHODS: Measles cases were identified by review of hospital emergency room and infection control logs and health department surveillance records. The Chandra Sekar Deming method was used (1) to estimate the total number of measles cases in persons less than 19 years old who presented to the 12 hospitals from January through March 1991 and (2) to estimate reporting efficiency. Information on mechanisms for reporting measles cases was collected from hospital infection control coordinators. RESULTS: The Chandra Sekar Deming method estimated that 1487 persons with measles presented to the 12 hospitals during the study period. The overall reporting efficiency was 45% (range = 19% to 83%). All 12 hospitals had passive surveillance for measles; 2 also had an active component. These 2 hospitals had the first and third highest measles reporting efficiencies. CONCLUSIONS: The reporting efficiency of measles cases by New York City hospitals to the health department was low, indicating that the magnitude of the outbreak was substantially greater than suggested by the number of reported cases.

Preschool children at high risk for measles: opportunities to vaccinate.

OBJECTIVES: In 1989 and 1990 the United States experienced a measles epidemic with more than 18,000 and 27,000 reported cases, respectively. Nearly half of all persons with measles were unvaccinated preschool children under 5 years of age. We sought to identify potential sites for vaccine delivery. METHODS: Preschool children with measles were surveyed in five inner cities with measles outbreaks in 1989 to 1990 to assess the children's use of health care services and federal assistance programs before contracting measles. RESULTS: Of 972 case children surveyed, 618 (64%) were eligible for measles vaccination at measles onset. Of those, 93% had previously visited a health care provider (private physician, public clinic, hospital emergency department, or hospital outpatient department) and 65% were enrolled in a federal assistance program (AFDC, WIC, or food stamps). Based on parent-reported reasons for health care visits, in Dallas and New York City, health care providers of 24% of 172 children may have missed at least one opportunity to administer measles vaccine. CONCLUSIONS: Many potential opportunities exist to raise the vaccination coverage of unvaccinated preschool children. These opportunities depend on (1) health care providers taking advantage of all opportunities to vaccinate, and (2) immunization services being linked to federal assistance programs.

High attack rates and case fatality during a measles outbreak in groups with religious exemption to vaccination.

Beginning in October, 1990, a large measles outbreak involving predominantly unvaccinated preschool age children occurred in Philadelphia. By June, 1991, 938 measles cases had been reported to the Philadelphia Health Department. In addition to these cases, 486 cases and 6 measles-associated deaths occurred between November 4, 1990, and March 24, 1991, among members of 2 Philadelphia church groups that do not accept vaccination. We identified measles cases and collected information on symptoms and potential risk factors for complications. Telephone interviews were conducted to collect demographic and clinical information on measles cases in church member households. We identified 486 measles cases among 892 mostly unvaccinated church members. Age-specific attack rates were highest among children 1 to 4 years of age (94%) and 5 to 14 years of age (91%). Five (83%) of the 6 deaths occurred in females, 3 of whom had underlying illnesses. The overall case-fatality rate was 1.2%. The case-fatality rate was 2% for females, 0.4% for males (P = 0.22), 1.7% for primary cases and 0.7% for secondary household cases (P = 0.67). Only one of the children who died had received medical care. Measles spread rapidly in this group, sparing few susceptible individuals. Lack of medical care and underlying disease appear to have contributed to the high case-fatality rate in the church communities.

Measles surveillance--United States, 1991.

A total of 9,643 measles cases was reported from the United States in 1991, a 65.3% decrease from the 27,786 cases reported in 1990. The overall incidence of measles was 3.9 cases per 100,000 population. The highest age-specific incidence was among children < 12 months of age (46.9/100,000) and 1-4 years of age (19.6/100,000). Incidence rates among American Indians, Hispanic, and black children < 5 years of age were 19, 6, and 4 times that for non-Hispanic white children, respectively. More than 61% of all cases were reported from seven large outbreaks, which involved predominantly unvaccinated preschool-age children in large urban areas. Although reported measles cases decreased in 1991 compared with 1989-1990, only a sustained effort to provide age-appropriate vaccination will prevent another resurgence of measles.

Epidemiology of measles in the United States in 1989 and 1990.

During 1989 and 1990 measles incidence increased sharply in the United States. We compared cases reported during these years with those reported between 1981 and 1988. Incidence increased 462% in 1989, and incidence in 1990 (11.2/100,000) was the highest in more than a decade. Although all ages were affected the greatest increases were in children < 5 years and in adults. Incidence was 7- to 10-fold higher among racial/ethnic minority preschoolers than whites, and 80% of vaccine-eligible preschool age cases were unvaccinated. Complications occurred in 9418 (20.5%) cases, most frequently in young children and adults. Large urban outbreaks affecting predominantly unvaccinated preschoolers were common; 47% of all cases reported in 1990 were associated with 5 outbreaks. Reasons for the increased incidence are not clear. Current information suggests no change in vaccination coverage among preschool age children or in vaccine efficacy. Continued surveillance and evaluation of epidemiologic and laboratory data are necessary. The most pressing need is to improve age-appropriate vaccination among preschool age children.