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PubMed2001

Time trends in autism and in MMR immunization coverage in California.

CONTEXT: Considerable concern has been generated in the lay and medical communities by a theory that increased measles-mumps-rubella (MMR) immunization among young children may be the cause of an apparent marked increase in autism occurrence. OBJECTIVE: To determine if a correlation exists in secular trends of MMR immunization coverage among young children and autism occurrence. DESIGN, SETTING, AND PARTICIPANTS: Retrospective analyses of MMR immunization coverage rates among children born in 1980-1994 who were enrolled in California kindergartens (survey samples of 600-1900 children each year) and whose school immunization records were reviewed to retrospectively determine the age at which they first received MMR immunization; and of autism caseloads among children born in these years who were diagnosed with autism and were enrolled in the California Department of Developmental Services regional service center system. MAIN OUTCOME MEASURES: Measles-mumps-rubella immunization coverage rates as of ages 17 months and 24 months and numbers of Department of Developmental Services system enrollees diagnosed with autism, grouped by year of birth. RESULTS: Essentially no correlation was observed between the secular trend of early childhood MMR immunization rates in California and the secular trend in numbers of children with autism enrolled in California's regional service center system. For the 1980-1994 birth cohorts, a marked, sustained increase in autism case numbers was noted, from 44 cases per 100 000 live births in the 1980 cohort to 208 cases per 100 000 live births in the 1994 cohort (a 373% relative increase), but changes in early childhood MMR immunization coverage over the same time period were much smaller and of shorter duration. Immunization coverage by the age of 24 months increased from 72% to 82%, a relative increase of only 14%, over the same time period. CONCLUSIONS: These data do not suggest an association between MMR immunization among young children and an increase in autism occurrence.

Autistic Disorder↗
PubMed2004

Cost-lowering strategies used by medicare beneficiaries who exceed drug benefit caps and have a gap in drug coverage.

CONTEXT: The majority of Medicare drug benefits in managed care (Medicare + Choice) have annual dollar limits or caps and many beneficiaries face temporary but potentially significant gaps in coverage after exceeding caps before the end of the year. In the new national Medicare drug benefit, beneficiaries with high medication expenditures will also face a period without drug coverage when their total drug costs exceed annual caps but are not high enough to qualify for catastrophic coverage. OBJECTIVE: To describe strategies adopted by beneficiaries exceeding annual drug benefit caps to lower prescription costs, the type of medications involved, and their financial burden. DESIGN, SETTING, AND PARTICIPANTS: A survey (completed in 2002) of Medicare + Choice beneficiaries aged 65 years and older with high medication costs and benefits capped on the plan's share of drug costs (65% response rate). The different caps offered in different counties were used as a natural experiment. Study participants (n = 665) exceeded a 750 dollars or 1200 dollars yearly cap in 2001 and had coverage gaps of 75 to 180 days. Control participants (n = 643) had 2000 dollars caps, which they did not exceed. Study and control participants were matched by average total drug expenditures per month. MAIN OUTCOME MEASURES: Proportion of beneficiaries reporting specific strategies to decrease medication costs, medications affected, and difficulty paying for prescriptions. RESULTS: In multivariate analyses adjusting for demographic and health characteristics, a higher proportion of patients exceeding caps reported using less prescribed medication than controls (18% vs 10%, respectively; P<.001), but similar proportions reported stopping medications completely (8% for both, P =.86) and of not starting prescribed medications (6% vs 5%, P =.39). Patients exceeding caps more often called pharmacies to find the best price (46% vs 29%, P<.001), switched medications (15% vs 9%, P =.002), used samples (34% vs 27%, P =.006), and had difficulty paying for prescriptions (62% vs 37%, P<.001). Twelve of the 20 therapeutic classes most often affected by decreases in use of medication were for chronic health problems such as hypertension, hyperlipidemia, and emphysema or asthma. CONCLUSIONS: Medicare beneficiaries often decreased use of essential medications and experienced difficulty paying for prescriptions during gaps in coverage. Health professionals need to explore how they can lessen the impact of caps on patients' health and financial burden.

Aged↗
PubMed2005

Improved proteome coverage by using high efficiency cysteinyl peptide enrichment: the human mammary epithelial cell proteome.

Automated multidimensional capillary liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been increasingly applied in various large scale proteome profiling efforts. However, comprehensive global proteome analysis remains technically challenging due to issues associated with sample complexity and dynamic range of protein abundances, which is particularly apparent in mammalian biological systems. We report here the application of a high efficiency cysteinyl peptide enrichment (CPE) approach to the global proteome analysis of human mammary epithelial cells (HMECs) which significantly improved both sequence coverage of protein identifications and the overall proteome coverage. The cysteinyl peptides were specifically enriched by using a thiol-specific covalent resin, fractionated by strong cation exchange chromatography, and subsequently analyzed by reversed-phase capillary LC-MS/MS. An HMEC tryptic digest without CPE was also fractionated and analyzed under the same conditions for comparison. The combined analyses of HMEC tryptic digests with and without CPE resulted in a total of 14 416 confidently identified peptides covering 4294 different proteins with an estimated 10% gene coverage of the human genome. By using the high efficiency CPE, an additional 1096 relatively low abundance proteins were identified, resulting in 34.3% increase in proteome coverage; 1390 proteins were observed with increased sequence coverage. Comparative protein distribution analyses revealed that the CPE method is not biased with regard to protein M(r) , pI, cellular location, or biological functions. These results demonstrate that the use of the CPE approach provides improved efficiency in comprehensive proteome-wide analyses of highly complex mammalian biological systems.

Amino Acid Sequence↗
PubMed2006

Pneumococcal serogroups and serotypes in severe pneumococcal pneumonia in Belgian children: theoretical coverage of the 7-valent and 9-valent pneumococcal conjugate vaccines.

BACKGROUND: Although the causative pneumococcal serotypes of invasive diseases are already extensively studied, few data are available about the pneumococcal serotypes additionally isolated from broncho-alveolar lavage samples in childhood pneumonia. STUDY AIM: To identify the causative pneumococcal serotypes in culture proven childhood community acquired pneumonia (CAP) and to calculate the effectiveness of the heptavalent and nonavalent pneumococcal vaccine (7- and 9-valent PnV) in severe pneumococcal pneumonia. METHODS: All pneumococcal isolates stored from broncho-alveolar lavage, blood culture and pleural fluid in healthy children with CAP were characterized. RESULTS: Seventy children (median age 2 years 3.5 months) could be included. The most prevalent serotypes were: SGT1 (21.4%), SGT6 (20.0%), SGT19 (12.8%), SGT23 (10.0%), and SGT14 (7.1%). SGT1 was especially prevalent in complicated cases and children >5 years. This first ranking of SGT1 is not reported in invasive pneumococcal disease studies. The overall theoretical coverage of the 7-valent PnV and the 9-valent PnV for pneumococcal pneumonia was 45.7% and 72.8%. The theoretical coverage of both vaccines was equal for non-invasive pneumonia (64%) but the theoretical coverage of the 9-valent PnV for invasive pneumonia was much higher (79% vs. 37.2%). Antibiotic susceptibility to penicillin was 84%, 70% to tetracycline and 61% to erythromycin; however only one strain (MIC = 4 mg/L) was highly resistant to penicillin. CONCLUSIONS: Based on this serotyping, the theoretical coverage of the 7-valent PnV for proven pneumococcal pneumonia is good but decreases with age. A 9-valent PnV containing SGT1 could significantly increase the coverage, especially for invasive pneumonia. According to these data, penicillin remains the first choice antibiotic treatment for childhood CAP in Belgium.

Adolescent↗
PubMed2005

Influenza vaccination of hospital staff in Germany: a five-year survey on vaccination coverage and policies: identified deficits in influenza immunisation campaigns for hospital employees.

OBJECTIVES: Influenza vaccination of hospital staff is recommended by STIKO, the German committee for vaccination. A survey was conducted to assess compliance with this recommendation. The occupational health services of 25 hospitals participated in a survey and provided data by questionnaire on influenza vaccination and on hospital policies to promote coverage of employees. METHODS: Vaccination activities were monitored by occupational health services (OHS) for five consecutive years from 1997 to 2002. The hospital sample covered a total of 17,089 beds (3.23% of the hospital capacity in Germany) and a total number of 41,969 employees (4.39% of hospital staff). RESULTS: The proportion of hospitals actively offering influenza vaccination increased from 48 % in 1997/98 to 92% in 2001/02. Vaccination coverage of all staff in 1997 was only 3.3% and reached 8.4% in 2001/02. Coverage of vaccinating hospitals increased from 5.0% to 10.4%. Poster campaigns and managing board commitment had significant impact. CONCLUSIONS: Considerable progress has been made to involve more hospitals and to increase coverage for vaccination of hospital employees. Nevertheless, coverage levels remain unacceptably low. Recommendations are ignored extensively.

Germany↗
PubMed2001

Population coverage by HLA class-I restricted cytotoxic T-lymphocyte epitopes.

Vaccination using cytotoxic T-lymphocyte (CTL) epitopes has become a widely used immunization strategy, especially because their structure makes them an attractive alternative to the delivery of whole proteins as immunogens. Nonetheless, their use is limited, in particular because of their specificity, being recognized only by cognate HLA alleles. The potential for immunizing a substantial portion of an ethnically diverse population using a modest number of peptides has been aided by the identification of HLA supertypes. However, the derivation of epitopes is often guided by methods that do not guarantee cross-reactivity, so we consider the feasibility of providing vaccine coverage to a multi-ethnic population under different assumptions. In particular, two large datasets are used to estimate the number of peptides needed to provide > or =90% group-specific coverage of a multiethnic population, when specificity is assumed to be either to a single serologic or molecular type. These assumptions are evaluated utilizing a clinically important epitope repertoire derived from two human cytomegalovirus proteins, and data on the in vitro memory response elicited by these peptides is presented. In summary, our combined theoretical and empiric studies suggest that 90% coverage of some ethnic groups is attainable with 11 uniquely defined HLA-restricted CTL epitopes. The derivation of four or more additional CTL epitopes is needed to attain 90% coverage of Blacks or Asians, the minimally covered groups. Ninety percent coverage of all major ethnic groups in a multi-ethnic population appears feasible without relying on cross-reactivity, but may require two to three times more CTL epitopes than estimated for serologic data, homogenous populations, or HLA alleles grouped as supertypes.

Alleles↗
PubMed1998

Simulation of acetabular coverage of femoral head using anteroposterior pelvic radiographs.

We developed a computer program to perform three-dimensional analysis of the acetabular coverage of the femoral head using two anteroposterior (supine and erect) radiographs of the hip. The center of radiation was marked, and an additional vertical line was placed on radiographs in the neutral standing position, permitting estimation of change in pelvic tilt and its effect on acetabular coverage. We studied 64 normal hip joints, 82 acetabular dysplastic hip joints, and 15 hip joints that had undergone rotational acetabular osteotomy (RAO). In normal hips, the pelvis tilted posteriorly on standing, and the anterior acetabular coverage decreased, but the extent of reduction was not significant. However, in dysplastic hip joints, the pelvic tilt changed from the posterior to anterior direction and from the painful side to the nonpainful side with progression of osteoarthritis. While RAO provided sufficient correction of anterior coverage for acetabular dysplasia, lack of posterior coverage was sometimes observed.

Acetabulum↗
PubMed2004

Staple line coverage with absorbable mesh after thoracoscopic bullectomy for spontaneous pneumothorax.

BACKGROUND: Thoracoscopic simple bullectomy for primary spontaneous pneumothorax (PSP) has a relatively high postoperative recurrence rate and sometimes results in postoperative air leakage. One of the reasons for postoperative recurrence is the regrowth of bullae around the staple line. Therefore, reinforcement of the visceral pleura around the staple line is a reasonable way to prevent postoperative air leaks and recurrence. This study was done to determine the efficacy in preventing postoperative air leak and recurrent pneumothorax of widely covering the staple line with absorbable mesh after thoracoscopic bullectomy. METHODS: Wide coverage of the staple line with absorbable mesh was performed on 114 patients with PSP. These patients were retrospectively compared with 126 patients who underwent thoracoscopic simple bullectomy alone. RESULTS: The postoperative duration of chest drainage in the coverage group (mean, 1 day; range, 0-5) was significantly shorter than that in the simple bullectomy group (mean, 3 days; range 0-20). A prolonged air leak (>7 days) occurred in six patients in the simple bullectomy group, but there were no such leaks in the coverage group. Recurrent pneumothorax occurred in three patients (2.6%) in the coverage group and 12 patients (9.5%) in the simple bullectomy group. CONCLUSION: Wide coverage of the staple line with absorbable mesh is effective in preventing postoperative air leak and in decreasing the recurrence rates of PSP.

Adolescent↗
PubMed2005

Intraabdominal adhesion formation of polypropylene mesh. Influence of coverage of omentum and polyglactin.

BACKGROUND: Adhesions after intraabdominal surgical procedures are related to high morbidity and mortality. Biomaterials, particularly those made of polypropylene, in the intraabdominal position have to be considered as pathophysiological cofactor in a multifactorial process of adhesion formation. To investigate the adhesive potential induced by the biomaterial, an animal model was performed. In addition, the influence of coverage by omentum or a polyglactin barrier was investigated. METHODS: In, 18 Chinchilla rabbits the biomaterial was placed laparoscopically using the intraperitoneal onlay mesh technique. Using this model, a polypropylene-polyglactin mesh compound (PPMC) was used with three different implantation techniques: group 1, PPMC implantation without coverage (PPMC): group 2, PPMC implantation with additional omentum coverage (PPMC-O): and group 3, PPMC implantation with coverage of an absorbable polyglactin mesh (PPMC-V). The degree of adhesion formation was measured 90 days after implantation by computer-assisted planimetry. Morphometric examination followed the explantation analyzing the amount of foreign body response. RESULTS: We found a significant reduction of adhesion formation for the PPMC and PPMC-O groups compared to the PPMC-V group, in which dense adhesions were found. Morphometric investigations of the perifilamental granulomas of the pure (PPMC) group revealed a typical foreign body reaction with a mild to moderate fibrosis around all mesh fibers. However, tissue specimens of the PPMC-O and PPMC-V groups indicated a similar inflammatory reaction but significantly increased connective tissue formation around the polymer fibers compared to the pure PPMC group. CONCLUSION: The intraabdominal placement of a pure PPMC shows a neoperitonealization and perifilamental collagenous ingrowth with almost no adhesions. Coverage with omentum (PPMC-O) or polyglactin mesh (PPMC-V) resulted in a significant increase in inflammation and perifilamentary connective tissue formation.

Animals↗
PubMed2006

Influenza vaccination coverages among Spanish children, adults and health care workers.

BACKGROUND: This study aimed at describing influenza vaccination coverage among Spanish children, adults and health care workers (HCWs). PATIENTS AND METHODS: We analyzed 27,791 questionnaires on subjects aged 6 months or over, drawn from the 2003 Spanish National Health Survey. As the dependent variable, we took the answer to the question, "Did you (or your child) have a flu shot in the last campaign?". Independent variables were age group, gender, nationality, occupation (HCWs) and coexistence of chronic conditions. RESULTS: Overall influenza vaccination coverage for the total sample was 19.58%. Coverage for the pediatric population was 5.55%, with 20.74% of those with and 4.67% of those without chronic condition being vaccinated. Vaccination coverages were: 63.7% among subjects aged > or = 65 years; 30.5% among high-risk subjects aged < 65 years; and 19.65% among HCWs. CONCLUSIONS: We conclude that the available results show low levels of influenza vaccination coverage among high-risk subjects aged under 65 years, children in particular, and HCWs.

Adolescent↗
PubMed1994

Health cards, maternal reports and the measurement of immunization coverage: the example of Guatemala.

Immunization against major childhood diseases has been an essential component of health policies in developing countries. However, despite its importance and the efforts invested by many organizations in promoting immunization programs, consistent and accurate measurement of immunization coverage has not yet been achieved. In this paper, we explore the implications of alternative methods of measuring immunization coverage rates in Guatemala, using data from the 1987 Encuesta Nacional de Salud Materno Infantil, and we consider the dangers of making inferences about levels and trends in coverage from cross-sectional data. The results indicate that (1) service statistics may well lead to overestimates of coverage; (2) survey estimates derived from health cards can also produce severely biased estimates; and (3) in spite of problems associated with maternal recall, mothers' reports of their children's vaccination status probably result in substantially improved estimates of immunization coverage.

Bias↗
PubMed1994

Neointimal coverage of stents in human coronary arteries observed by angioscopy.

OBJECTIVES: The aim of this study was to reveal the time course of the neointimal coverage of stents placed in the human coronary arteries. BACKGROUND: In deciding the protocol of anticoagulant and antiplatelet therapy for patients who undergo stent implantation, the condition of the neointimal coverage of stents should be taken into consideration. However, the time course of the neointimal coverage of stents has not been elucidated in human coronary arteries. METHODS: Serial angioscopic observations were performed immediately after stenting, at 8 to 45 days (short-term follow-up) and at 65 to 142 days (long-term follow-up) in patients who underwent implantation of the Wiktor coronary stent in the restenotic lesion or in the lesion of acute or threatened closure after balloon angioplasty. RESULTS: Angioscopic observations were successfully performed in 14 cases immediately after stenting, in 11 cases at short-term follow-up and in 13 cases at long-term follow-up. Immediately after stenting and even at 8 to 18 days after stenting, the stent was not covered by the neointimal layer in any case. However, at 65 to 142 days after stenting, the stent was covered by the neointimal layer in all cases. Angioscopically, three types of neointimal layer were recognized: a white layer with a cottonlike surface in three cases, a white layer with a smooth surface in eight cases and a transparent layer with a smooth surface in two cases. CONCLUSIONS: Although some experimental results in animals have shown completion of neointimal coverage of stents in a few weeks, in this serial angioscopic follow-up study, the completion of neointimal coverage of stents in human coronary arteries required approximately 3 months.

Angioscopy↗
PubMed1985

Incidence of 24-hour faculty coverage in teaching EDs.

There is growing concern in academic emergency medicine as to the appropriateness of 24-hour faculty coverage in the teaching emergency department. We surveyed 170 teaching emergency departments, 49 of which had approved emergency medicine residencies, asking for information regarding 24-hour faculty coverage. We were able to separate each department into one of 15 profiles based on the two variables of average ED yearly census and hospital type. Seventy-three percent of university teaching hospital EDs and 65% of those with emergency medicine residencies have 24-hour faculty coverage; 83% of private teaching hospital EDs and 100% of those with emergency medicine residencies have 24-hour faculty coverage; and 79% of city/county teaching hospital EDs and 80% of those with emergency medicine residencies have 24-hour faculty coverage.

Emergency Medicine↗
PubMed2005

Examining the coverage of influenza vaccination among people with cardiovascular disease in the United States.

BACKGROUND: People with chronic cardiovascular conditions are at increased risk of developing complications from relative common influenza infection. METHODS: We examined the coverage of influenza vaccination during the past 12 months among people with cardiovascular disease (CVD) using data from the National Health Interview Survey 2002. RESULTS: The coverage of influenza vaccination among people with CVD was observed to be less than optimum (32.7%) after adjusting for age. Among separate components studied, the coverage of influenza vaccination was highest among people with congestive heart failure (37.1%) and lowest among people with stroke (31.4%). Hypertension was the most commonly reported condition with influenza vaccination coverage of 32.6%. Only 22% of people with CVD aged <50 years reported receiving influenza vaccine in the past 12 months. For people in higher age groups with CVD, the coverage was 40.5% and 69.9% among people aged 50 to 64 years and > or =65 years, respectively. CONCLUSIONS: People with CVD, especially those <50 years of age, should be encouraged to receive influenza vaccination to prevent influenza-related cardiovascular complications.

Adolescent↗
PubMed2004

Physician and enrollee knowledge of Medicaid coverage for tobacco dependence treatments.

BACKGROUND: The 2000 Public Health Service Clinical Practice Guideline, Treating Tobacco Use and Dependence, recommends health insurance coverage for tobacco-dependence treatments proven effective in helping smokers to quit. Two states with comprehensive coverage for tobacco-dependence treatments in their Medicaid programs were selected to document awareness of coverage for tobacco-dependence treatments among primary care physicians who treat Medicaid enrollees and Medicaid-enrolled smokers. METHODS: In 2000, surveys were conducted among Medicaid smokers (n =400) and physicians (n =160) to document knowledge of covered tobacco-dependence treatments under state Medicaid programs in two states with comprehensive coverage. RESULTS: Only 36% of Medicaid-enrolled smokers and 60% of Medicaid physicians knew that their state Medicaid program offered any coverage for tobacco-dependence treatments. Physicians were more than twice as likely to know that pharmacotherapies were covered compared to counseling. CONCLUSIONS: Greater effort is needed to make Medicaid smokers and physicians aware that effective pharmacotherapies and counseling services are available to assist in treating tobacco dependence. Additionally, future research should explore the methods that are most effective in informing patients and providers regarding covered benefits.

Adolescent↗
PubMed2005

Vaccination coverage survey versus administrative data in the assessment of mass yellow fever immunization in internally displaced persons--Liberia, 2004.

Yellow fever (YF) is a mosquito-borne vaccine-preventable disease with high mortality. In West Africa, low population immunity increases the risk of epidemic transmission. A cluster survey was conducted to determine the effectiveness of a mass immunization campaign using 17D YF vaccine in internally displaced person (IDP) camps following a reported outbreak of YF in Liberia in February 2004. Administrative data of vaccination coverage were reviewed. A cluster sample size was determined among 17,384 shelters using an 80% vaccination coverage threshold. A questionnaire eliciting demographic information, household size, and vaccination status was distributed to randomly selected IDPs. Data were analyzed to compare vaccination coverage rates of administrative versus survey data. Among 87,000 persons estimated living in IDP camps, administrative data recorded 49,395 (57%) YF vaccinated persons. A total of 237 IDPs were surveyed. Of survey respondents, 215 (91.9%, 95% CI 88.4-95.4) reported being vaccinated during the campaign and 196 (83.5%, 95% CI 78.6-88.5) possessed a valid campaign vaccination card. The median number of IDPs living in a shelter was 4 (range, 1-8) and 69,536 persons overall were estimated to be living in IDP camps. Coverage rates from a rapid survey exceeded 90% by self-report and 80% by evidence of a vaccination card, indicating that the YF immunization campaign was effective. Survey results suggested that administrative data overestimated the camp population by at least 20%. An emergency, mop-up vaccination campaign was avoided. Coverage surveys can be vital in the evaluation of emergency vaccination campaigns by influencing both imminent and future immunization strategies.

Adolescent↗
PubMed2004

Cataract surgical coverage and outcome of cataract surgery in a rural district in Malawi.

BACKGROUND: Cataract is the leading cause of blindness in Malawi. We sought to determine the cataract surgical coverage and the outcome of cataract surgery in a rural district in Malawi to assess past performance of cataract surgical services. METHODS: From July to October 1999 we conducted a multistage random cluster survey to include 1630 residents aged 50 years or more in Chikwawa District. Visual acuity, cause of vision loss, history of cataract surgery and cause of poor vision (if less than 6/60) were assessed. Cataract surgical coverage, sight restoration rate and outcome were calculated by person and eye and for men and women separately. RESULTS: We examined 1384 people (84.9% of target). Twenty-one people (12 men and 9 women) (30 eyes) had received cataract surgery. The cataract surgical coverage rate was 35.6% (44.4% for men and 28.1% for women [odds ratio 2.0, 95% confidence interval 0.6-7.0]) at a visual acuity level of 6/60, and 55.3% (60.0% for men and 50.0% for women [odds ratio 1.5, 95% confidence interval 0.3-6.7]) at a level of 3/60. Only one eye of one subject had received an intraocular lens. Presenting visual acuity was 6/18 or better in 7 eyes (23.3%), 6/24 to 6/60 in 7 eyes, and worse than 6/60 in 16 eyes (53.3%). Among the 16 eyes with visual acuity less than 6/60, the vision could be improved in 8 with provision of aphakic spectacles. INTERPRETATION: Cataract surgical coverage in this population is similar to that reported from other countries in Africa. As in other settings, cataract surgical coverage was lower in women than in men. Poor outcomes in this population are partly due to surgical complications and partly due to a lack of aphakic correction. Surgical promotion programs will need to focus on differentiating intraocular lens surgery from (previously practised) intracapsular cataract extraction surgery.

Blindness↗
PubMed1998

The effect of community structure on the immunity coverage required to prevent epidemics.

Estimation of the immunity coverage required to effectively control disease transmission is an important public health problem. Using data on the eventual size of a major epidemic, we compare estimates based on the simplifying assumption that the community consists of uniformly mixing individuals with estimates obtained when the more complex community structure is acknowledged. The alternative community structures considered include households and localities that are quite separate. Several inequalities are established for estimates of the critical immunity coverage. For several settings, the coverage estimated by assuming an oversimplified community structure is found to actually be an underestimate. A serious consequence of this finding is that we may be misled into believing that we have estimated an immunity coverage that can prevent epidemics when it in fact cannot. The conclusion is that the heterogeneity in the community must be taken into account when estimating the critical immunity coverage.

Disease Outbreaks↗