The occurrence of pulmonary lesions in BCG-vaccinated and unvaccinated persons.
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BCG Vaccine↗
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Results for “Unvaccinated Persons”
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The comparison of some tuberculins in BCG-vaccinated and unvaccinated persons.
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Humans↗
[The different clinico-biological behavior of S.D.V.-vaccinated and unvaccinated persons in presence of highly infectious tubercular contagion].
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Child↗
[Study of the incidence of antipoliomyelitis antibodies of types I, II and III in unvaccinated persons in the rural areas of the R.P.R].
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Antibodies↗
Comparison of a whole-blood interferon gamma assay with tuberculin skin testing for detecting latent Mycobacterium tuberculosis infection.
CONTEXT: Identifying persons with latent tuberculosis infection (LTBI) is crucial to the goal of TB elimination. A whole-blood interferon gamma (IFN-gamma) assay, the QuantiFERON-TB test, is a promising in vitro diagnostic test for LTBI that has potential advantages over the tuberculin skin test (TST). OBJECTIVES: To compare the IFN-gamma assay with the TST and to identify factors associated with discordance between the tests. DESIGN AND SETTING: Prospective comparison study conducted at 5 university-affiliated sites in the United States between March 1, 1998 and June 30, 1999. PARTICIPANTS: A total of 1226 adults (mean age, 39 years) with varying risks of Mycobacterium tuberculosis infection or documented or suspected active TB, all of whom underwent both the IFN-gamma assay and the TST. MAIN OUTCOME MEASURE: Level of agreement between the IFN-gamma assay and the TST. RESULTS: Three hundred ninety participants (31.8%) had a positive TST result and 349 (28.5%) had a positive IFN-gamma assay result. Overall agreement between the IFN-gamma assay and the TST was 83.1% (kappa = 0.60). Multivariate analysis revealed that the odds of having a positive TST result but negative IFN-gamma assay result were 7 times higher for BCG-vaccinated persons compared with unvaccinated persons. The IFN-gamma assay provided evidence that among unvaccinated persons with a positive TST result but negative IFN-gamma assay result, 21.2% were responding to mycobacteria other than M tuberculosis. CONCLUSIONS: For all study participants, as well as for those being screened for LTBI, the IFN-gamma assay was comparable with the TST in its ability to detect LTBI, was less affected by BCG vaccination, discriminated responses due to nontuberculous mycobacteria, and avoided variability and subjectivity associated with placing and reading the TST.
Adult↗
Epidemiology of variola minor in Brazil based on a study of 33 outbreaks.
Surveillance-containment units were established in 1969 in four States of Brazil as part of the national smallpox eradication programme. Their responsibilities included both the investigation of reported cases and the control of outbreaks, and the further extension and development of the reporting network. Altogether, 33 outbreaks of smallpox were investigated in detail, all in endemic areas not yet reached by the attack phase of the eradication programme. Official reports of 27 cases led to the discovery of an additional 1 465 cases, suggesting that reporting was not more than 2% complete in endemic areas. The total of 1 492 cases in 33 outbreaks occurred in 493 households comprising a study population of 3 088 persons: three-quarters of the cases were in children under 15 years of age. Only 5% were in individuals aged 30 years or more. The case-fatality ratio was 0.8%. The overall attack rate among unvaccinated persons (76.2%) was 23 times that among vaccinated persons (3.3%). Age-specific vaccine effectiveness ratios ranged from 94% to 100% with an overall reduction in expected cases among the vaccinated of 95%. There was no evidence to suggest waning of immunity among persons who had been successfully vaccinated. There was an inverse relationship between susceptibility and age since a greater proportion of adults had already had smallpox or a successful vaccination; 97% of pre-school-age children and 82% of school-age children had no history of smallpox and no vaccination scar. In all 33 outbreaks, more than 60% of unvaccinated persons became ill; in 5 outbreaks the attack rate for unvaccinated persons was greater than 90%.
Adolescent↗
Functional status is a confounder of the association of influenza vaccine and risk of all cause mortality in seniors.
BACKGROUND: Functional status limitations may be associated with both an increased risk of death and a decreased likelihood of influenza vaccination, and so may confound the association of influenza vaccination and risk of all cause mortality in seniors. METHODS: We conducted a nested case-control study of persons >or=65 years of age that included 252 cases who died during an influenza season and 576 age-matched controls. We identified functional limitations by medical record review, and compared the effect of adjustment for those factors with that of adjustment for disease covariates defined by diagnosis codes, using methods reported by previous influenza vaccine effectiveness studies, on the association of influenza vaccination and risk of death. RESULTS: Functional limitations, such as requiring assistance for bathing, were highly prevalent in cases, even in the subgroup defined as free of comorbidity by diagnosis code criteria, and were associated with a decreased likelihood of vaccination among controls. Adjustment for functional limitations resulted in an estimate of the relative risk of death in vaccinated persons compared with unvaccinated persons that was closer to the null [odds ratio (OR), 0.71; 95% confidence interval (95% CI), 0.47-1.06] than the unadjusted estimate (OR, 0.59; 95% CI, 0.41-0.83). In contrast, adjustment for diagnosis code covariates moved the estimate further from the null (OR, 0.45; 95% CI, 0.30-0.68). CONCLUSIONS: Functional limitations appear to be important confounders of the association of vaccination and risk of death, while adjustment for diagnosis code covariates did not control for a healthy vaccinee bias. Further research is needed on methods to reduce the influence of bias in observational studies of influenza vaccine effectiveness.
Activities of Daily Living↗
Fatal respiratory diphtheria in a U.S. traveler to Haiti--Pennsylvania, 2003.
Respiratory diphtheria can be severe or fatal in unvaccinated persons; even with appropriate treatment, 5%-10% of patients with diphtheria die. For >50 years, vaccination against diphtheria has been recommended for children and adults in the United States. Persons who are unvaccinated or vaccinated inadequately can contract diphtheria during travel to areas where the disease is endemic, putting them and their close contacts at risk for severe illness. This report describes fatal respiratory diphtheria in an unvaccinated Pennsylvania resident who had visited Haiti, a country where the disease is endemic. The case highlights the need for all international travelers to be up-to-date with all recommended vaccinations, including a primary series of diphtheria toxoid-containing vaccine.
Diphtheria↗
Effect of influenza vaccination on disease progression among HIV-infected persons.
OBJECTIVE: To describe the effect of influenza vaccination on long-term change in CD4 count and HIV RNA level, and on progression to AIDS or death. DESIGN AND SETTING: A longitudinal medical record review set in 113 medical clinics in 10 United States cities. PATIENTS: A total of 36,050 HIV-infected persons aged > or = 13 years in care for HIV infection. MAIN OUTCOME MEASURES: Change in CD4 count and HIV RNA level at follow-up (3-12 months after vaccination); hazard ratios (HR) for association of influenza vaccine with progression from baseline CD4 or HIV RNA level to AIDS and to death. RESULTS: The median CD4 count among all persons decreased 28 cells/year during follow-up, with no difference in change in CD4 count between the 8007 (40%) vaccinated (median = 6 months, vaccine to follow-up CD4 count) and the 11,794 unvaccinated persons. In a viral load subanalysis, median HIV RNA level decreased 90 copies/ml per year among all persons during follow-up; decreases were not different between vaccinated and unvaccinated persons (median = 7 months, vaccine to follow-up HIV RNA level determination). Influenza vaccination was weakly associated with decreased risk of progression to clinical AIDS [HR 0.93; 95% confidence interval (CI), 0.87-0.99], but not associated with time to death (HR, 0.97; CI, 0.93-1.01). CONCLUSIONS: No negative long-term effect of influenza vaccination on CD4 counts, HIV RNA levels, or progression to AIDS or death was found in this HIV-infected population. These data suggest that physicians should not withhold influenza vaccine because of concerns about long-term detrimental effects of increased viral replication.
Acquired Immunodeficiency Syndrome↗
Relation between influenza vaccination and outpatient visits, hospitalization, and mortality in elderly persons with chronic lung disease.
BACKGROUND: Influenza vaccine is underused in groups targeted for vaccination. OBJECTIVE: To define the effects of influenza and the benefits of influenza vaccination in elderly persons with chronic lung disease. DESIGN: Retrospective, multiseason cohort study. SETTING: Large managed care organization. PATIENTS: All elderly members of a managed care organization who had a previous diagnosis of chronic lung disease. MEASUREMENTS: Outcomes in vaccinated and unvaccinated persons for the 1993-1994, 1994-1995, and 1995-1996 influenza seasons were compared after adjustment for baseline demographic and health characteristics. All data were obtained from administrative databases. RESULTS: Vaccination rates were greater than 70% for each season. Among unvaccinated persons, hospitalization rates for pneumonia and influenza were twice as high in the influenza seasons as they were in the interim (noninfluenza) periods. Influenza vaccination was associated with fewer hospitalizations for pneumonia and influenza (adjusted risk ratio, 0.48 [95% CI, 0.28 to 0.82]) and with lower risk for death (adjusted odds ratio, 0.30 [CI, 0.21 to 0.43]) during the influenza seasons. It was also associated with fewer outpatient visits for pneumonia and influenza and for all respiratory conditions. CONCLUSIONS: For elderly persons with chronic lung disease, influenza is associated with significant adverse health effects and influenza vaccination is associated with substantial health benefits, including fewer outpatient visits, fewer hospitalizations, and fewer deaths. Health care providers should take advantage of all opportunities to immunize these high-risk patients.
Age Factors↗
[Improving tetanus prevention in the Krasnodar area taking the current epidemic situation into account].
An increase of percentage of elderly persons among those who fell ill with tetanus (70%) was noted against a sharp reduction of tetanus incidence under the effect of mass active immunization against this disease. A study of immunity in older and elderly individuals showed the percentage of immune persons among them to be rather low (48.8--55.6%). Due to difficulty of elderly individuals embracement by vaccination the authors suggest a single immunization scheme with a double toxoid dose (20 BU) followed by revaccination with 10 BU in one year. A total of 21 472 persons were placed under observation. The suggested immunization scheme was harmless, promoted stimulation of antitetanus immunity in persons vaccinated earlier; as to unvaccinated persons--it created a favourable immunological preparedness for revaccination, permitting to do without any antitetanus serum in case of trauma.
Adolescent↗
Influence of high-risk medical conditions on the effectiveness of influenza vaccination among elderly members of 3 large managed-care organizations.
This serial cohort study assessed the risk of hospitalization or death associated with influenza and the effectiveness of influenza vaccination among subgroups of elderly members of 3 managed-care organizations in the United States. Data on baseline characteristics and outcomes were obtained from computerized databases. A total of 122,974 (1996-1997 season) and 158,454 (1997-1998 season) persons were included in the cohorts. Among unvaccinated persons, hospitalizations for pneumonia/influenza or death occurred in 8.2 of 1000 healthy and 38.4 of 1000 high-risk persons in year 1, and in 8.2 of 1000 healthy and 29.3 of 1000 high-risk persons in year 2. After adjustments, vaccination was associated with a 48% reduction in the incidence of hospitalization or death (95% confidence interval [CI], 42-52) in year 1 and 31% (95% CI, 26-37) in year 2. Effectiveness estimates were statistically significant and generally consistent across the healthy and high-risk subgroups. The absolute risk reduction, however, was 2.4- to 4.7-fold higher among high-risk than among healthy elderly persons. All elderly individuals may substantially benefit from vaccination. However, the impact of influenza is greater in persons with high-risk medical conditions.
Aged↗
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↗
Estimation of vaccine efficacy in outbreaks of acute infectious diseases.
In a previous paper we defined the efficacy of a vaccine as 1-beta 1/beta 0, where beta 0 is the instantaneous probability of transmission of infection to an unvaccinated person exposed to a single infectious person, and beta 1 is similarly defined for a vaccinated person. We showed that under the conditions of an outbreak of an acute, directly transmitted infectious disease in a homogeneous and randomly mixing population, an estimate of this measure of vaccine efficacy is 1-[1n(1-A1)/1n(1-A0)], where A0 and A1 are the observed final attack rates among unvaccinated and vaccinated persons, respectively. In the present work we present an approximation for the standard error of this estimator, accounting for both the sampling and process variation. We extend the results of our previous paper to a stratified population, where the strata correspond to different levels of susceptibility and may have different vaccination coverage. We also consider populations that consist of small units (for example, households) where individuals mix primarily in these units. In this case, definition of vaccine efficacy is in terms of the within-unit transmission probabilities and is estimable by using transmission models for infectious diseases. We apply the estimation methods described above to data from influenza and measles outbreaks. We also examine, via a stochastic simulation study, the robustness of the vaccine efficacy estimators under various population structures and mixing patterns.
Adolescent↗
Explosive school-based measles outbreak: intense exposure may have resulted in high risk, even among revaccinees.
Even high levels of measles vaccination coverage have not always prevented outbreaks of measles spread by airborne transmission. It has been suggested that a large inoculum might increase vaccine failure risk. Airbome transmission might occasionally entail a large measles inoculum. The epidemiologic relevance of measles among properly vaccinated persons (i.e., those vaccinated after 15 months of age and with live attenuated virus) is increased when they become contagious. The authors studied inoculum intensities as measured by proxy variables and the contagiousness of properly vaccinated persons who contracted measles among 51 measles patients infected in one school, at home, or elsewhere, utilizing preexisting records of measles cases and 214 healthy controls from an explosive school outbreak that occurred in a rural Finnish municipality in 1989. One "super-spreader" infected 22 others in one day, including eight once-vaccinated students and one twice-vaccinated student, probably during an assembly of 144 students in a poorly ventilated hallway with no sunlight. Those infected later at home had high measles risk, even if they were revaccinees. When siblings shared a bedroom with a measles case, a 78 percent risk (seven out of nine children) was observed among vaccinees. Vaccinees had approximately 2 days' shorter incubation time than unvaccinated persons. Vaccinated and unvaccinated students were equally able to infect their siblings. Total protection against measles might not be achievable, even among revaccinees, when children are confronted with intense exposure to measles virus.
Adolescent↗
[Function of tetanus immunoglobulin in case of injury: administration often unnecessary].
OBJECTIVE: To calculate the number of tetanus immunoglobulin (TIG) injections given in order to prevent one patient developing tetanus (number needed to treat (NNT)) and the accompanying costs. DESIGN: Functional study. METHOD: The risk of developing tetanus was calculated from the results of a national study on tetanus immunity in the general population of the Netherlands (1995-1996; n = 7715) and from official notifications of tetanus in the period 1984-1996 (n = 30 persons born before 1945). According to current vaccination policy TIG is advised for unvaccinated persons and those with an unclear vaccination status as well as those vaccinated more than 15 years ago. RESULTS: The tetanus risk after injury was estimated at 0.5-2 per million for unvaccinated individuals. Immunity was lowest (< 50%) in men born before 1936 and women born before 1950. The NNT for these groups was a minimum of 530.000. With a mortality of 10% and costs of 20 Euro per TIG injection, the cost of each life saved was found to be a minimum of 105 million Euro. The NNT and cost per life saved were astronomical for those persons born after 1955. CONCLUSION: The current TIG policy is inefficient. Thanks to the success of the National Immunisation Programme it is now justified to limit the administration of TIG to those who are at the highest risk i.e. those who are known to be unvaccinated, women born before 1950 and men born before 1936.
Aged↗
Progress towards eliminating Hib in Australia: an evaluation of Haemophilus influenzae type b prevention in Australia, 1 July 1993 to 30 June 2000.
The status of Haemophilus influenzae (Hib) disease and its prevention by vaccination was reviewed for the period 1997 to 2000. This forms the background to a change in national vaccine policy, from the use of two Hib vaccines to the use of PRP-OMP only throughout Australia from May 2000. Notifications of Hib in the 7-year period between 1993 and 2000 declined by 87 per cent among children 0-4 years of age; adjustment for likely under-reporting increase this to a 95 per cent reduction. Among age groups not included in the immunisation program, there was also a substantial decline in notified cases. Overall, a minimum 430 cases and 13 deaths were prevented by Hib immunisation annually in Australia. Enhanced Hib surveillance recorded 532 cases over seven years, with 353 in unvaccinated persons, 74 fulfilling criteria for true vaccine failure and 75 partially immunised. Of unvaccinated cases, 60 and 182 were eligible for routine and catch-up immunisation respectively. Although the overall incidence for 0-4 years of age declined from 15 to 1.2 cases per 100,000 population, the proportion of cases under six months of age increased from 11 per cent to 23 per cent. Overall vaccine effectiveness, estimated using data from the last five years of the program, was 83 per cent (95% CI 71-91%), increasing to 90 per cent (95% CI 83-94%) when adjusted for under-reporting to the Australian Childhood Immunisation Register. Among Aboriginal and Torres Strait Islander people, the incidence of invasive Hib disease fell from 4.6 cases per 100,000 population to 0.7 cases per 100,000 population but the proportion of cases now occurring among Aboriginal or Torres Strait Islander people increased significantly, from 7 to 15 per cent. The Hib immunisation program in Australia has been highly successful. Nevertheless, experience in Australia and elsewhere indicates that continued careful monitoring of Hib disease, with high quality laboratory surveillance, remains important.
Age Distribution↗
Interpretability and robustness of sieve analysis models for assessing HIV strain variations in vaccine efficacy.
From data on HIV-1 characteristics measured on viruses isolated from vaccinated and unvaccinated persons infected while enrolled in preventive HIV-1 vaccine trials, interpretable inferences into strain variations of vaccine efficacy can be made with recently developed sieve analysis models. Four assumptions are needed for the parameters in these models to have meaningful interpretations in terms of vaccine-induced reductions in strain-specific per-contact transmission probabilities: (A1) vaccination impacts each strain-specific transmission probability homogeneously in vaccinated persons (leaky vaccine effect); (A2) for each strain biological susceptibility to infection given exposure is homogeneous among vaccinated trial participants and among unvaccinated trial participants; (A3) the distribution of exposure is equal in vaccinated and unvaccinated trial participants; (A4) the relative prevalence of circulating HIV-1 strains during the trial follow-up period is constant. Through theoretical considerations and simulations of an ongoing phase III HIV-1 vaccine efficacy trial in Bangkok, we evaluate the importance and necessity of these assumptions. We show that the models still provide estimates of biologically interpretable parameters when A1 is violated, but with bias the extent to which vaccine protection is heterogeneous. We also show that the models are highly robust to departures from A4, with implication that the time-independent models are adequate for applications. In addition, we suggest extensions of the sieve analysis models which incorporate random effects that account for unmeasured heterogeneity in infection risk. With these mixed models, usefully interpretable strain-specific vaccine efficacy parameters can be estimated without requiring A2. The conclusion is that A3, which is justified by randomization and blinding, is the essential assumption for the sieve models to provide reliable interpretable inferences into strain variations in vaccine efficacy.
AIDS Vaccines↗