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A field trial of combined use of the basal body-temperature and the secretion of cervical mucus as a means of regulating births is reported. 84 women followed the method through 1195 cycles between October 1, 1973 and May 31, 1976. There were 22 unplanned pregnancies.
Field trials were conducted using an experimental, modified live virus, oral vaccine for prevention of reo- and coronavirus calf diarrhea. Prior to the trials, one or both of the specific causative agents were identified from affected calves in each participating herd. In 21 herds, sequential trials were conducted in which results of uninterrupted vaccination were compared with disease rates during a preceding or subsequent control period. In these herds there was a statistically significant reduction in the morbidity and mortality from disease in 1,598 vaccinates compared with the rates in 829 prevaccination control calves. Morbidity and mortality in 206 post-vaccination control calves rose marginally above the rates in the same vaccinates. In 26 other herds, where double blind trials were conducted, rates of morbidity and mortality from disease were virtually the same for 1,080 vaccinated calves and 355 placebo calves. Vaccinates in the sequential trials had the lowest morbidity and mortality rates of any test group in either field trial format. In a selected dairy herd, both field trial formats were implemented and the results compared. In the double blind trial, vaccinates and placebo calves had comparable rates of morbidity and mortality from disease. When a sequential trial was later implemented, a statistically significant reduction in morbidity and mortality occurred in vaccinates compared with rates in control calves.
The encouraging results of an earlier controlled field trial of the serogroup A meningococcal polysaccharide vaccine in the prevention of clinical disease prompted this study, the aim of which was to evaluate further the effectiveness of another lot of this type of vaccine, the duration of immunity, and the effectiveness against meningococcal carriage. A controlled field trial was carried out in early 1973 on 176 646 schoolchildren 6-15 years of age, of whom half received the serogroup A polysaccharide vaccine and the other half tetanus toxoid as a control. The incidence of cerebrospinal meningitis caused by serogroup A meningococci was 89% lower in the immunized group than in the controls for one year only. With regard to its effect on carriage, the vaccine was found to reduce to less than half the rate of new acquisition of serogroup A meningococci during the period immediately following immunization. The duration of the carrier state was also shortened in the immunized group.
Even though a preventive agent has been shown to be powerful in reducing the incidence of, for example, dental caries when tested in a longitudinal clinical trial, it might not be as powerful when tested under more realistic environmental conditions. Field trials or field demonstration programs will provide the final evidence for determining if the agent or procedure is of such practical importance as to be included as a component in a dental care delivery system. The methodology developed for health services research provides the possibility of testing the effectiveness of a single or combined components in a dental care delivery system seen in relation to the environment and conditions under which it operates. The World Health Organization is at present involved in the implementation of a long range of field demonstration programs in various parts of the world especially in developing countries in order to establish the potential of known preventive procedures in population groups with different levels and different progression patterns of oral diseases.
A field trial was carried out in the eastern part of the State of Minas Gerais (Brazil) of a vaccine containing killed promastigotes of five stocks of Leishmania. Tests with Montenegro antigen showed that a high proportion of the vaccinated persons became positive within three months, but circulating antibodies were not detected. A proportion of those vaccinated continued to give positive Montenegro reactions for up to three years. Lymphocyte sensitivity tests carried out, on a small sample, three years after vaccination were positive and gave no evidence of immunological depression. No cases of cutaneous or mucocutaneous leishmaniasis occurred in the trial area during the three years of observations.
The results of three serologically controlled double blind field trials in army units are presented. The evaluation of results according to morbidity, regardless of aetiology, showed a significant reduction in acute respiratory diseases (ARD) after administration of Impulsin. In the 1973 trial (901 volunteers), 22.7% of ARD cases were found in the Impulsin group contrary to 34.4% in the placebo group (P less than 0.0002). The relevant values in the 1974 trial (610 volunteers) were 19.7% and 40.7% (P less than 0.002) and in the 1975 trial (353 volunteers) 10.6% and 28.8% (P less than 0.004). The study of the immunological background in representative sets of volunteers allowed determination of the aetiology, the proportion of asymptomatic infections and possible deformation of results due to preexisting protective antibodies. Manifestation rate (MR) expressing the proportion of sick persons out of all sensitive subjects with serologically proved infection was found useful. This indicator is relatively independent of randomization and is more sensitive as compared to the incidence rate. In the 1973 trial, influenza A 2 England was prevalent, the MR of infection being 15.4% in the Impulsin group and 44.9% in the placebo group (P less than 0.0002). After elimination of persons with preinfection antibodies greater than or equal to 1:256 the corresponding values of MR were 17.6% and 46.6% (P less than 0.005), reflecting the "relatively clean effect" of Impulsin. In the 1974 trial, where influenza B Hong-Kong was prevalent, MR was 14.3% and 57.1%, respectively (P less than 0.001). Preinfection antibodies were negligible. The preliminary prophylactic index of the drug seemed to be 4.3 for combined adenoviral infections (trials 1973 and 1974 taken together). In the 1975 trial, the results of serological examination were unsatisfactory. Antibodies vs. influenza A Port Chalmers were found in 24.5% of ARD only. The differnce is aetiologically unclarified ARD was statistically significant. Although displaying a significant limitation of clinical infections, the administration of Impulsin did not seem to have any influence on the formation of antibodies.
Field trials were conducted on attenuated live virus vaccine of transmissible gastroenteritis to confer active immunity to newborn piglets. To examine innocuity and efficacy of the vaccine, a total of 714 newborn piglets were subjected to these trials. Of them, 357 piglets were administered orally with 10(7.0) TCID50 within 3 days after birth, and the other 357 piglets served as nonvaccinated controls. No undesirable postvaccinal reaction was observed in any vaccinated piglet. Suckling piglets born from nonimmune sows showed a good antibody response after vaccination. They were different, however, in antibody titer from one experimental place to another. Antibody levels were high in piglets raised in the northern experimental places. On the contrary, the antibody response of suckling piglets born from immune sows was influenced by vaccination. In most of these piglets, antibody titers declined markedly and disappeared finally 3 months after vaccination. About 25% of the non-vaccinated piglets showed an antibody response by pen contact with vaccinated ones.
A controlled field trial of a modified vaccine containing Salmonella typhi, TY 2 strain, in a dose of 400 x 10(9) killed organisms per capsule, was carried out in schoolchildren aged 6-17 years. The children were followed up for 6-8 months. There were 66 cases of typhoid fever in the vaccine group (7312 children) and 54 in the control group (7292 children who had received a placebo). This difference is not statistically significant. The results confirm that, as found in earlier trials, oral typhoid vaccine, in the dosages used so far, gives no protection.
A controlled field trial comparing the effectiveness of a plain cholera vaccine with that of a vaccine adsorbed to aluminium hydroxide was carried out in a cholera-endemic area of Indonesia during 1973-75. Tetanus toxoid adsorbed to aluminium phosphate was used as the control. In vaccinees aged 1-4 years, the adsorbed cholera vaccine provided about 88% protection for 6 months following vaccination and still provided about 50% protection between 11 and 14 months after vaccination. In the same age group, the plain vaccine provided only 53% protection during the first 6 months and no appreciable protection beyond that period. In those aged 5 years and over, both vaccines provided 50-60% protection throughout the period of observation (14 months). Neither vaccine caused any serious side effects.
The protective effect of a lyophilized vaccine against Marek's disease ("Keramvac"--Pfizer), prepared from a cell-free turkey's herpesvirus (strain FC 126), was compared in field trials with losses in the group of non-vaccinated chickens. Under the indicated conditions, the vaccine had only a 50.86% effectiveness. The possible causes of the reduced vaccination effect are discussed with regard to the pathomorphological and virological findings suggesting, among others, an increased incidence of the symptoms of the classical form of Marek's disease in the population investigated.
The interrater agreement for major diagnostic categories in studies using DSM-I and DSM-II was usually only fair or poor. In phase one of the DSM-III field trials the overall kappa coefficient of agreement for axis I diagnoses of 281 adult patients was .78 for joint interviews and .66 for diagnoses made after separate interviews; for axis II--personality disorders and specific developmental disorders--the coefficients of agreement were .61 and .54. The interrater reliability of DSM--III is, in general, higher than that previously achieved and may be due to changes in the classification itself, the separation of axis I from axis II conditions, the systematic description of the various disorders, and the inclusion of diagnostic criteria.
More recent investigations on the duration of effect and plasma half-life of propranolol suggest a simplification of dosage for the beta-blocker in the treatment of hypertension. A field trial with Dociton 80 twice daily as initial therapy was carried out in over 2000 patients with essential hypertension with relatively few side effects and confirmed the distinctly longer-persisting effect of the beta-blocker on longterm application. Including the marginal values, the response rate in this collective was relatively high at 73%.
The multiaxial system of DSM-III includes nondiagnostic data that are valuable in understanding possible etiological factors and in treatment planning and prognosis. The authors describe the reliability of axis IV--severity of psychosocial stressors--and axis V--highest level of adaptive functioning in the past year--for 281 adult patients interviewed in phase one of the DSM-III field trials. The kappa coefficient of agreement for axis IV was .62 for joint interviews and .58 for separate interviews, which the authors consider at least fair. Reliability for axis V was quite good, .80 for joint interviews and .69 for separate interviews. Eighty-one percent of the participating clinicians judged the multiaxial system to be a useful addition to traditional diagnostic evaluation, although many indicated that they had difficulty quantifying severity of psychosocial stressors.
Studies in animals have shown that effective immunity can be induced by vaccines employing plasmodial sporozoites, asexual blood forms (e.g., merozoites), and sexual blood forms (gametocytes/gametes). In the future, but only when extensive safety testing has shown them suitable for administration to human subjects, the efficacy of such vaccines in the control of malaria in human populations will need to be assessed. Field trials will pose many complex problems and assessment of the results they yield will demand precise and detailed information first on the frequency, density of parasitaemia, and clinical severity of malarial episodes in vaccinated and control subjects and second, on the changes that occur in the gametocyte reservoir and entomological indices of transmission within the trial area. They will require to be sited in areas where the prevalence, importance and epidemiology of malaria is known with precision and where much additional information on the endemicity of non-malarial illnesses is available. Trials will entail close collaboration with experienced statisticians and meticulous planning, with special emphasis on the design of an efficient records system. The services of experienced clinicians skilled in the diagnosis and treatment of malarial and non-malarial illnesses will also be essential. Surveillance of the indices of malaria transmission will require competent entomological expertise.
A series of laboratory trials on a number of different types of inactivated Pasteurella anatipestifer vaccines suggested that a formolised vaccine would be the most suitable for protection. A satisfactory dose of vaccine was found to be approximately 3 x 109 cells administered intramuscularly. The efficacy of this vaccine was confirmed by a field trial on a farm where anatipestifer septicaemia was endemic, ducks being vaccinated at three weeks of age before their transfer to pasture from indoor rearing units.
An inactivated whole-virus vaccine was prepared from the influenza virus recombinant H0N2 and administered to two groups of subjects. A total of 1,200 subjects were vaccinated; comparable groups of subjects served as controls. From a portion of the vaccinees sera were obtained prior to vaccination and three to four weeks afterwards. Serological tests revealed development of or increase in the antibody against H0 in a great majority of the vaccinated subjects and against N2 in slightly more than half of them. Antibody response to H3 antigen was only rarely encountered. Approximately three months after vaccination an influenza epidemic caused by Victoria-like (H3N2) viruses broke out in Czechoslovakia. Numerous influenza cases occurred in the two populations followed. Morbidity was significantly lower among the vaccinated than among the control subjects, indicating a protective effect of the neuraminidase vaccine under field conditions.
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A national study of the new specific assays for prostatic acid phosphatase was conducted by the National Prostatic Cancer Project. The results of the study have confirmed that the counterimmunoelectrophoretic method is easily reproducible, highly specific, and sufficiently sensitive. Based on tests as performed by different institutions, the counterimmunoelectrophoretic (CIEP) method was also shown to have high reproducibility and was found to be of much greater sensitivity than the conventional biochemical methods for the detection of earlier stages of prostatic cancer. The national study of the radioimmunoassay (RIA) has shown that although being a highly sensitive method, it could not be readily distributed at this time from one specialized center. It requires highly specific, expensive technical assistance and is not yet available nationwide. CIEP is recommended at this time to be used as the preferred method in the evaluation and diagnosis of prostatic cancer. The value of counterimmunoelectrophoresis in detecting early prostatic cancer as a screening method is promising, but still under study.