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S C Hadler

Publications and source records attributed to S C Hadler.

At least 37 records · Page 2Linked to original sources
PubMed1995

Defining surrogate serologic tests with respect to predicting protective vaccine efficacy: poliovirus vaccination.

Inactivated and trivalent oral poliovirus vaccines contain either formalin-inactivated or live, attenuated poliovirus, respectively, of the three serotypes. Interference among the three attenuated poliovirus serotypes was minimized with a "balanced-formulation" vaccine, and serologic responses after IPV were optimized by adjusting the antigenic content of each inactivated poliovirus serotype. Seroconversion is dependent on both the relative content as well as the absolute quantity of virus in the vaccine. The "gold standard" method to assess humoral antibody responses following vaccination is the neutralization assay. Any detectable titer of neutralizing antibody against poliovirus is considered protective against clinical paralytic diseases. Recently, standard procedures were adopted for conducting neutralization assays. Efforts are being undertaken now to develop a combined diphtheria and tetanus toxoids and pertussis vaccine and IPV vaccine in the United States using a dual-chambered syringe that mixes the content of both vaccines at the time of injection; this approach is necessary to overcome the potential detrimental effect of thimerosal on IPV (the preservative in DTP). Other vaccines that combine DTP and/or Haemophilus influenzae type b and/or hepatitis B with IPV appear feasible but require further investigation. New combination vaccines should induce similar or superior levels of neutralizing antibody in serum for individual protection against paralytic disease and mucosal immunity that effectively decreases viral replication in the intestine and pharynx for population protection against transmission of poliovirus.

Antibodies, Viral↗
PubMed1993

Delta hepatitis: molecular biology and clinical and epidemiological features.

Hepatitis delta virus, discovered in 1977, requires the help of hepatitis B virus to replicate in hepatocytes and is an important cause of acute, fulminant, and chronic liver disease in many regions of the world. Because of the helper function of hepatitis delta virus, infection with it occurs either as a coinfection with hepatitis B or as a superinfection of a carrier of hepatitis B surface antigen. Although the mechanisms of transmission are similar to those of hepatitis B virus, the patterns of transmission of delta virus vary widely around the world. In regions of the world in which hepatitis delta virus infection is not endemic, the disease is confined to groups at high risk of acquiring hepatitis B infection and high-risk hepatitis B carriers. Because of the propensity of this viral infection to cause fulminant as well as chronic liver disease, continued incursion of hepatitis delta virus into areas of the world where persistent hepatitis B infection is endemic will have serious implications. Prevention depends on the widespread use of hepatitis B vaccine. This review focuses on the molecular biology and the clinical and epidemiologic features of this important viral infection.

Animals↗
PubMed1993

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.

Child Health Services↗
PubMed1993

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.

Adolescent↗
PubMed1993

Successes and failures in vaccine delivery: evaluation of the immunization delivery system in Puerto Rico.

The objective of this study was to evaluate immunization delivery and determine reasons for low coverage among preschool-age public clinic attendees in Puerto Rico. In 25 randomly selected clinics, coverage and missed immunization opportunities were assessed in 273 children aged 2 to 59 months, exist interviews were conducted with parents, and providers were interviewed. Two neighborhoods close to the clinics were surveyed to determine parental knowledge about immunizations, and the vaccination status of children in these neighborhoods was assessed. Two hundred seventy-three clinic attendees were interviewed. Among 229 (84%) with vaccination cards, only 126 (55%) had received all indicated vaccines by completion of the clinic visit. Forty-five percent of children with cards in the household survey were not up-to-date. Of 171 (75%) clinic attendees eligible for vaccination at the visit, 118 (69%) missed one or more immunizations at the visit. In addition, half of all children had previously missed one or more immunizations when they had received another vaccine. Missed opportunities occurred because of nonavailability of vaccines, lack of integration of services, provider misconceptions about contraindications, and failure to administer vaccines simultaneously. Other problems included barriers to immunization services and lack of information and education activities. It is concluded that deficiencies in immunization delivery substantially delay immunization and reduce coverage.

Child↗
PubMed1992

Epidemiology and long-term consequences of hepatitis delta virus infection in the Yucpa Indians of Venezuela.

To define better the epidemiology and clinical impact of hepatitis delta virus (HDV) infection among hepatitis B virus (HBV) carriers in less developed countries, the authors prospectively studied a cohort of 216 Yucpa Indian HBV carriers in Venezuela. HBV carriers were followed regularly between 1983 and 1988 by physical examination, laboratory testing for liver enzymes and HBV and HDV markers, and epidemiologic history. Among the cohort, 74 (34%) were initially positive for HDV infection, and 35 additional persons became infected during the study. Risk factors for new HDV infection included living in southern Yucpa villages; being young adults (15-19 years) or young children (1-9 years), and living in a household with a person with acute HDV infection. Persons with HDV infection were at high risk of developing chronic liver disease; 56% of HDV-infected persons had moderate-to-severe chronic liver disease at the end of the study compared with none of the HBV carriers without HDV infection. Mortality rates were 6.9% and 8.8% per year, respectively, among initially HDV-positive HBV carriers and those with new HDV infection, because of rapidly progressive chronic liver disease and fulminant hepatitis; mortality was significantly lower in HBV carriers without HDV infection and in non-HBV carriers. HDV superinfection is a devastating disease in HBV carriers in tropical South America. Prevention of HBV infection with hepatitis B vaccine is the best available tool to reduce the impact of this problem.

Acute Disease↗
PubMed1992

Pertussis surveillance--United States, 1989-1991.

The licensure of whole-cell pertussis vaccine combined with diphtheria and tetanus toxoids as DTP in the 1940s--and its widespread use in infants and children--led to a dramatic decline in the incidence of reported pertussis. In the prevaccine era, the average annual incidence and mortality for reported pertussis were 150 cases and six deaths per 100,000 population, respectively. From 1989 to 1991, pertussis cases were reported by state and local health departments to CDC through two distinct national surveillance systems: the National Notifiable Diseases Surveillance System (NNDSS) and the Supplementary Pertussis Surveillance System (SPSS). During the period 1989-1991, 11,446 pertussis cases were reported to the NNDSS (4,157 in 1989; 4,570 in 1990; and 2,719 in 1991), for an unadjusted annual incidence of 1.7, 1.8, and 1.1 cases per 100,000 population in 1989, 1990, and 1991, respectively. For the period 1989-1991, case reports were received through the SPSS on 9,480 (83%) of the 11,446 patients reported to the NNDSS. Age-specific incidence and hospitalization rates were highest among children < 1 year of age and declined with increasing age. Long-term trends suggest an increase in the reported incidence of pertussis in the United States since 1976. The peak in reported pertussis cases in 1990 represents the highest annual incidence of pertussis since 1970. However, the incidence of pertussis declined 41% from 1990 through 1991. Whether the long-term increase in reported pertussis is a true increase in incidence is unclear; the observed increase may be a function of improved surveillance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

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.

Adolescent↗
PubMed1992

Hepatitis B vaccination in children: five year booster study.

AIM: to demonstrate that appropriate doses of hepatitis B vaccines would be protective for at least five years in children. This would be shown by administering booster doses and measuring the response. METHODS: 2 micrograms intramuscular (IM) doses of Merck Sharp and Dohme (MSD) recombinant DNA vaccine (rDNAV) were given to 318 children who had received age appropriate doses of MSD plasma derived vaccine (PDV) five years earlier. Sera were tested for hepatitis B virus (HBV) seromarkers pre- and postbooster. RESULTS: all children who had responsed to primary immunisation demonstrated an anamnestic response. The geometric mean titre (GMT) of antibody to hepatitis B surface antigen (antiHBs) rose from 89 to 4777 IU/L. AntiHBs was detected in 94% of vaccinees just prior to the five year booster, and 96.5% a mean of 10 days later. CONCLUSION: when initial vaccine seroconversion is satisfactory, protection of responders persists for at least five years, assuming that the response to vaccine boosters mimics the response to wild virus. Therefore, for population control of hepatitis B in children in endemic areas, booster doses are not required for at least five years.

Antibodies, Viral↗