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S E Robertson

Publications and source records attributed to S E Robertson.

At least 37 records · Page 2Linked to original sources
PubMed1997

The WHO Global Programme for Vaccines and Immunization Vaccine Trial Registry.

In 1995, the WHO Global Programme for Vaccines and Immunization established a Vaccine Trial Registry. As of September 1996, this registry included 50 WHO-supported vaccine trials, of which 25 (50%) were completed studies. The vaccines most frequently tested have been against measles (9 trials), poliovirus (8 trials), cholera (8 trials), enterotoxigenic Escherichia coli (4 trials), and pneumococcus (4 trials). Nearly 80% of these trials have been conducted in developing countries, with the largest number being in Africa. Among the 25 completed trials, outcomes measured were immune response (24 trials), adverse reactions (13 trials), morbidity (4 trials), and mortality (1 trial). WHO's contributions to these studies include direct funding, assistance with study design, site visits, data analysis, vaccine procurement, and vaccine potency testing.

Adolescent↗
PubMed1997

The lot quality technique: a global review of applications in the assessment of health services and disease surveillance.

Since the mid-1980s, there has been growing interest in adapting the lot quality (LQ) technique to monitor the quality of health care services, especially in developing countries. This global review has identified a total of 34 LQ surveys conducted from 1984 to 1996 in Africa, the Americas, Europe, South-East Asia, and the Western Pacific. Health care parameters assessed in the surveys varied and some surveys assessed more than 1 health parameter: 24 surveys assessed immunization coverage, 9 examined women's health issues such as family planning and antenatal care, 5 assessed use of oral rehydration therapy, 5 estimated disease incidence, and 3 others evaluated health worker performance. These studies indicate that LQ is a practical, relatively low-cost field method which is increasingly being applied in health programmes.

Developing Countries↗
PubMed1996

Yellow fever: a decade of reemergence.

Since the 1980s, yellow fever has reemerged across Africa and in South America. The total of 18 735 yellow fever cases and 4522 deaths reported from 1987 to 1991 represents the greatest amount of yellow fever activity reported to the World Health Organization (WHO) for any 5-year period since 1948. There is an excellent vaccine against yellow fever. At present, a high proportion of travelers to at-risk areas are reported to be immunized, reflecting widespread knowledge about the International Health Regulations. In South America, yellow fever remains an occupational hazard for forest workers, who should be immunized. However, Aedes aegypti mosquitoes are now present in urban areas in the Americas (including southern parts of the United States), and there is concern that yellow fever could erupt in explosive outbreaks. In Africa, a large proportion of cases have occurred in children. The WHO, the United Nations Children's Fund (UNICEF), and the World Bank have recommended that 33 African countries at risk for yellow fever add the vaccine to the routine Expanded Programme on Immunization; studies show that this would be highly cost-effective. To date, financing yellow fever vaccine has been a major problem for these countries, which are among the poorest in the world. For this reason, WHO has launched an appeal to raise $70 million for yellow fever control in Africa.

Africa↗
PubMed1996

Immunization against diphtheria with special emphasis on immunization of adults.

A massive diphtheria epidemic in Eastern Europe has resulted in increased anxiety that this disease could spread to other countries. This fear is realistic because there is a gap in the diphtheria immunity in large segments of the adult population in many industrialized countries. Experience to date suggests that an immunity gap in adults coupled with the presence of large numbers of susceptible children and adolescents creates the potential for an extensive epidemic. To prevent epidemics, countries should consider the immunogenicity and duration of protection provided by diphtheria toxoid given to children in the primary series and as booster doses. This paper reviews general issues related to the formulation of diphtheria immunization strategies, especially the need for booster doses in adults and the rationale for use of lower-strength diphtheria toxoid for persons older than 6 years of age.

Adult↗
PubMed1995

Resurgence of diphtheria.

Following the introduction of routine immunization with diphtheria toxoid in the 1940s and 1950s, diphtheria incidence declined dramatically in countries of the industrialized world. At the beginning of the 1980s many of these countries were progressing toward elimination of the disease. However, since the mid-1980s there has been a striking resurgence of diphtheria in several countries of Eastern Europe. For 1993, WHO received reports of 15,211 diphtheria cases in Russia and 2,987 cases in Ukraine. The main reasons for the return of diphtheria in these countries were: decreasing immunization coverage among infants and children waning immunity to diphtheria in adults, movements of the population during the last few years, and an irregular supply of vaccines. The outbreak spread to neighboring countries and in 1993 cases were reported in Azerbaijan, Belarus, Estonia, Finland, Kazakhstan, Latvia, Lithuania, Poland, Tajikistan, Turkey, and Uzbekistan. Epidemiological patterns of diphtheria are changing in developing countries, and the disease seems to be following patterns seen in industrialized countries 30 to 40 years ago. In developing countries, routine immunization against diphtheria was introduced in the late 1970s with the Expanded Programme on Immunization. In these countries, coverage of infants with 3 doses of diphtheria toxoid reached 46% in 1985, and 79% in 1992. Recent diphtheria outbreaks in Algeria, China, Ecuator, Jordan, Lesotho and Sudan demonstrate a shift in the age distribution of cases to older children and adults. Rapid clinical and public health responses are required to control diphtheria outbreaks. Three major measures are indicated: high immunization coverage of target groups, prompt diagnosis and management of diphtheria cases, and rapid identification of close contacts with their effective management to prevent secondary cases.

Adolescent↗
PubMed1995

Diphtheria: changing patterns in the developing world and the industrialized world.

In the past, diphtheria was considered one of the most serious childhood diseases because it took a heavy toll in health and life among preschool-aged children. Prior to the widespread availability of diphtheria toxoid, nearly 70% of cases were in children younger than 15 years of age. In the industrialized countries, immunization against diphtheria became widespread in the 1940s and 1950s. This led to a marked decrease in the incidence of diphtheria. There was also a decrease in circulating toxigenic Corynebacterium diphtheriae organisms, resulting in less natural boosting of antibody levels. This had led to gaps in the immunity of the adult population. Since 1990, diphtheria has made a spectacular comeback in several European countries, with a high proportion of cases in adults. In developing countries, immunization of infants with diphtheria toxoid was introduced with the Expanded Programme on Immunization in the late 1970s. Coverage rose slowly to 46% in 1985 and 79% in 1992. Because the pool of immunized persons is not yet large, the process of maintaining immunity still operates through natural mechanisms, including frequent skin infections caused by C. diphtheriae. But recently, several developing countries where coverage has been high for 5-10 years have reported diphtheria outbreaks. These outbreaks have been characterized by high case fatality rates, a large proportion of patients with complications, and their occurrence in both young and older age groups. In all countries, priority should be given to efforts to reach at least 90% coverage with three doses of diphtheria toxoid in children below one year of age. In countries where diphtheria has been successfully controlled, immunity levels should be maintained by booster doses.

Adolescent↗
PubMed1995

Seroresponse to trivalent oral poliovirus vaccine as a function of dosage interval.

Seroresponses to trivalent oral poliovirus vaccine are not uniform throughout the world. Definition of the variables that determine successful immunization is vital to ensure global polio eradication. One such variable may be dosage interval. To investigate this effect 108 infants were enrolled in a clinical trial and randomly assigned to receive three doses of trivalent oral poliovirus vaccine (standard United States formulation) at 2, 3 and 4 or 2, 4 and 6 months of age. After three doses of vaccine given before 6 months of age, immunity was virtually complete for each of the three poliovirus types in both groups. After two doses the seroresponse rate to each type was less with the shorter dose interval. However the difference was not significant (P = 0.15) in the sample size studied. Such responses differ markedly from those seen in developing countries, where four or more doses of vaccine may fail to provide complete protection. Differences other than dosage interval must contribute to those failures.

Antibodies, Viral↗
PubMed1994

Poliomyelitis in Oman: acute flaccid paralysis surveillance leading to early detection and rapid response to a type 3 outbreak.

Countries are increasingly requesting guidance on carrying out acute flaccid paralysis (AFP) surveillance, aimed at detecting and confirming all cases of acute paralytic poliomyelitis. The experience of Oman provides many lessons in this respect. AFP surveillance in Oman was established systematically. First, an epidemiologist was assigned to coordinate surveillance, and a laboratory for performing polio-virus isolation was identified. Next, operational guidelines for AFP surveillance were developed and widely promoted among health staff. The quality of the system has been monitored for more than 3 years with selected performance indicators. From January 1990 to April 1993, 49 AFP cases were reported, corresponding to an average annual rate of 2.1 AFP cases per 100,000 children aged less than 15 years. A total of 98% of the AFP cases were investigated within 48 hours of being reported; two stool samples were obtained from 94% of the cases. Following complete investigation, nearly a third of the reported AFP cases were classified as being clinically compatible with Guillain-Barré syndrome. Four AFP cases, all reported in 1991, were confirmed to be due to wild type 3 poliovirus. Because AFP surveillance detected these cases rapidly, Oman was able to carry out outbreak control measures promptly and more than 350,000 extra doses of oral poliovirus vaccine were delivered to children under 6 years of age.

Adolescent↗
PubMed1994

Interrupting the transmission of wild polioviruses with vaccines: immunological considerations.

In 1988 the World Health Assembly set the goal of global poliomyelitis eradication by the year 2000. Substantial progress has been made, and 143 countries reported no poliomyelitis cases associated with the wild virus in 1993. This article reviews the immunological considerations relevant to interrupting the transmission of wild polioviruses with vaccines. Although serum immunity prevents poliomyelitis in the individual, it is local immunity that is important in preventing the transmission of polioviruses in the community. Natural infection and vaccination with oral polioviruses vaccine (OPV) produce local immunity in the intestine and the nasopharynx in about 70-80% of individuals. In contrast, inactivated poliovirus vaccine (IPV) produces local intestinal immunity in only 20-30% of the individuals. With either vaccine, however, a substantial proportion of the immunized population can transmit the wild virus. Moreover, although serum immunity is long-lasting, limited data suggest that local immunity may not be as persistent. To interrupt the transmission of wild polioviruses efforts should be made to achieve and sustain high levels of poliovirus vaccine coverage. Recent outbreaks show that wild poliovirus poses a risk for unimmunized individuals, even when overall coverage levels are high. Delivery of poliovirus vaccine to hard-to-reach populations will be of increasing importance as countries progress toward the final stages of poliomyelitis eradication. The immunization status of persons from poliomyelitis-free countries should be updated prior to travel to poliomyelitis-endemic areas.

Antibodies, Viral↗
PubMed1994

Enhanced survival from cecal ligation and puncture with pentoxifylline is associated with altered neutrophil trafficking and reduced interleukin-1 beta expression but not inhibition of tumor necrosis factor synthesis.

BACKGROUND: Our preliminary results showed that pentoxifylline improves survival after cecal ligation and puncture (CLP), even though in this model inhibition of tumor necrosis factor (TNF) activity decreases survival. In this study we tested the hypothesis that pentoxifylline improves survival after CLP, not by inhibiting TNF synthesis but by exerting its effect on leukocyte adhesiveness, neutrophil sequestration, recruitment of cells into the focus of sepsis, and interleukin-1 (IL-1) expression. METHODS: Pentoxifylline, 10 or 100 mg/kg/day, was administered to mice after CLP by infusion for 3 days. The following was measured at 24 hours for the group with improved survival: (1) serum TNF by enzyme-linked immunosorbent assay, (2) TNF and IL-1 beta mRNAs in lung and peritoneal macrophages by the differential polymerase chain reaction, (3) lung myeloperoxidase by a colorimetric assay, (4) leukocyte CD11b/CD18 by flow cytometry, and (5) peritoneal exudate cells by manual counting. RESULTS: Only the low-dose pentoxifylline increased survival. Pentoxifylline reduced IL-1 beta mRNA expression in lung and peritoneal macrophages but not TNF mRNA or immunoreactive TNF in the serum. The myeloperoxidase content of lung was reduced by pentoxifylline, but leukocyte CD11b/CD18 expression did not change. Pentoxifylline increased the number of cells in the peritoneum after CLP. CONCLUSIONS: Pentoxifylline improves survival after CLP without inhibiting TNF synthesis or expression of CD11b/CD18 on leukocytes. Pentoxifylline treatment reduced lung neutrophil sequestration and IL-1 beta mRNA levels and increased cell recruitment in the peritoneum.

Animals↗
PubMed1993

Studies of missed opportunities for immunization in developing and industrialized countries.

Missed opportunities for immunization are an obstacle to raising immunization coverage among children and women of childbearing age. To determine their global magnitude and reasons, studies reported up to July 1991 were reviewed. A standard measure for the prevalence of missed opportunities was calculated for each study. Seventy-nine studies were identified from 45 countries; 18 were population-based, 52 were health-service-based, and 9 were intervention trials. A median of 32% (range, 0-99%) of the children and women of childbearing age who were surveyed had missed opportunities during visits to the health services for immunization or other reasons. Missed opportunities were mainly due to failure to administer simultaneously all vaccines for which a child was eligible; false contraindications; health workers' practices, including not opening a multidose vaccine vial for a small number of persons to avoid vaccine wastage; and logistical problems. To eliminate missed opportunities for immunization, programmes should emphasize routine supervision and periodic in-service training of health workers which would ensure simultaneous immunizations, reinforce information about true contraindications, and improve health workers' practices.

Adult↗
PubMed1992

Serological and virological assessment of oral and inactivated poliovirus vaccines in a rural population in Kenya.

A study was carried out in a rural community in Kenya to compare the humoral and intestinal immunity provided by three doses of oral poliovirus vaccine (OPV) and two or three doses of enhanced-potency inactivated poliovirus vaccine (IPV). The immunization series was started at 8-12 weeks of age and the interval between doses was 2 months. In children with low levels of maternal antibodies (i.e., those most at risk), the first dose of either vaccine stimulated antibody response. Children with high levels of maternal antibodies responded to the first dose of OPV, but not to that of IPV. Subsequent doses led to increases in the mean antibody titres with both vaccines. After three doses of OPV, the proportion of children with antibody titres of greater than or equal to 1:8 was 92% for type 1 virus, 98% for type 2, and 90% for type 3. After two doses of IPV the proportion of children with antibody titres of greater than or equal to 1:8 was 94%, 88%, and 97% for type 1, type 2, and type 3, respectively; after three doses of IPV, 100% of children had antibodies greater than or equal to 1:8 for types 1 and 3, and 98% for type 2. Intestinal immunity was tested with a challenge dose of type 1 OPV, but the dose used was too small to detect a significant difference between the vaccines.

Antibodies, Viral↗
PubMed1990

Worldwide status of poliomyelitis in 1986, 1987 and 1988, and plans for its global eradication by the year 2000.

In 1986, a total of 28,951 cases of poliomyelitis were reported to WHO by 175 countries/areas. For 1987, 35,685 cases were reported by 168 countries/areas. Reporting is incomplete for 1988, based on data available as of December 1989. Trends in regional incidence rates for poliomyelitis over a 15-year period from 1974 to 1988 suggest a decline in the incidence of the disease, especially since 1982. However, the reported data underreport actual disease incidence. During 1986, 1987 and 1988, the Expanded Programme on Immunization (EPI) estimates that 200,000-250,000 cases of paralytic poliomyelitis occurred each year. With the current level of polio immunization coverage, it is estimated that 360,000 cases of paralytic poliomyelitis were prevented in 1988. In 1974, when the EPI was started, it was estimated that less than 5% of children in the developing world were adequately immunized against six common childhood diseases, including poliomyelitis. In 1988 (based on data available as of December 1989) 67% of children worldwide received a full course of polio vaccine before 12 months of age. The progress of the EPI has provided optimism that poliomyelitis can be eradicated. In May 1988, the Forty-first World Health Assembly committed WHO to the global eradication of poliomyelitis by the year 2000. The eradication of poliomyelitis will represent, along with the eradication of smallpox, a fitting gift from the XXth to the XXIst century. To reach this goal, action will be required in several main areas. Immunization coverage will need to be raised and sustained in every district. Vaccine quality must be assured by using vaccines which meet WHO requirements and maintaining the cold chain. Surveillance must be strengthened so that prompt, regular reporting of suspected cases leads to disease-containment measures. Additional actions include improving laboratory diagnostic capabilities, developing special training materials, increasing public awareness, supporting rehabilitation services and conducting essential research.

Forecasting↗
PubMed1988

Clinical efficacy of a new, enhanced-potency, inactivated poliovirus vaccine.

The 1986-87 outbreak of paralytic poliomyelitis in Senegal, with 676 reported cases, provided an opportunity to evaluate the efficacy of an enhanced-potency inactivated poliovirus vaccine (N-IPV) in the Kolda region, where this vaccine has been used since 1980. 89 cases, confirmed to have poliomyelitis with residual paralysis, were enrolled in a case-control study, up to 5 matched controls being obtained for each case. The clinical efficacy for one dose of N-IPV was 36% (95% confidence interval 0%, 67%) and for two doses was 89% (95% CI 62%, 97%).

Adolescent↗
PubMed1987

Preventing rubella: assessing missed opportunities for immunization.

Cases of rubella continue to occur among adults in the United States because 10-20 per cent of persons in this age group remain susceptible. To evaluate the potential preventability of these cases, we present a method for assessing missed opportunities for rubella immunization, based on immunization recommendations of the Immunization Practices Advisory Committee (ACIP) of the US Public Health Service (PHS). Immunization programs faced with limited resources can use analysis of missed opportunities to focus on those gaps in implementation contributing most to the remaining rubella cases.

Adolescent↗
PubMed1984

Decreased neutrophil chemotaxis and chronic granulomatous disease.

A case of chronic granulomatous disease associated with decreased neutrophil chemotaxis is described. It is suggested that defective neutrophil motility may be more common than previously recognized in chronic granulomatous disease. However, the presence of a chemotactic defect does not necessarily imply a more severe clinical course.

Cell Migration Inhibition↗