Influenza vaccination: policy versus evidence: no gap between policy and evidence.
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Evidence-Based Medicine↗
Biomedical subjects
Kristin L Nichol
Publications and source records attributed to Kristin L Nichol.
Vaccines for seasonal and pandemic influenza.
Seasonal influenza continues to have a huge annual impact in the United States, accounting for tens of millions of illnesses, hundreds of thousands of excess hospitalizations, and tens of thousands of excess deaths. Vaccination remains the mainstay for the prevention of influenza. In the United States, 2 types of influenza vaccine are currently licensed: trivalent inactivated influenza vaccine and live attenuated influenza vaccine. Both are safe and effective in the populations for which they are approved for use. Children, adults <65 years of age, and the elderly all receive substantial health benefits from vaccination. In addition, vaccination appears to be cost-effective, if not cost saving, across the age spectrum. Despite long-standing recommendations for the routine vaccination of persons in high-priority groups, US vaccination rates remain too low across all age groups. Important issues to be addressed include improving vaccine delivery to current and expanded target groups, ensuring timely availability of adequate vaccine supply, and development of even more effective vaccines. Development of a vaccine against potentially pandemic strains is an essential part of the strategy to control and prevent a pandemic outbreak. The use of existing technologies for influenza vaccine production would be the most straightforward approach, because these technologies are commercially available and licensing would be relatively simple. Approaches currently being tested include subvirion inactivated vaccines and cold-adapted, live attenuated vaccines. Preliminary results have suggested that, for some pandemic antigens, particularly H5, subvirion inactivated vaccines are poorly immunogenic, for reasons that are not clear. Data from evaluation of live pandemic vaccines are pending. Second-generation approaches designed to provide improved immune responses at lower doses have focused on adjuvants such as alum and MF59, which are currently licensed for influenza or other vaccines. Additional experimental approaches are required to achieve the ultimate goal for seasonal and pandemic influenza prevention--namely, the ability to generate broadly cross-reactive and durable protection in humans.
Adjuvants, Immunologic↗
Heterogeneity of influenza case definitions and implications for interpreting and comparing study results.
There is substantial heterogeneity with regard to influenza case definitions used in the medical literature. These different case definitions can vary substantially with regard to their sensitivity, specificity and positive and negative predictive values for confirmed influenza. Because of this heterogeneity, it is important that the appropriate case definitions be used to answer the specific questions of the study, with more specific definitions likely being used to answer questions of vaccine efficacy and more sensitive definitions being used to assess overall disease burden. When interpreting the results of studies and comparing results across studies it is essential that the issue of heterogeneity of case definitions be addressed, and that absolute risk reduction be used as the main outcome measure of interest rather than just the relative risk reduction.
Humans↗
Benefits of influenza vaccine in US elderly--appreciating issues of confounding bias and precision.
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Aged↗
Safety of influenza vaccinations administered in nontraditional settings.
Nontraditional settings (NTS) are increasingly utilized for adult vaccination but concerns exist about their safety. We conducted this analysis of 542,445 persons vaccinated at an NTS in Minnesota to assess the safety of influenza vaccination in NTS. A total of 112 adverse events (AEs) were reported, 95 immediate and 17 late. Most AEs were mild and resolved within several minutes. 63 persons (.01%) had a vasovagal reaction to vaccination and 22 (.004%) reported an injection site problem. Immediate hypersensitivity reactions were very rare with only 10 (.002%) vaccine recipients having an immediate reaction for which epinephrine was required. Fifteen (.003%) individuals required evaluation in an emergency room or physician's office because of an AE. No deaths were reported. We conclude that influenza vaccine administration in mass vaccination clinics is safe and adverse events after influenza vaccination in NTS are extremely low.
Drug-Related Side Effects and Adverse Reactions↗
Impact of a winter respiratory virus season on patients with COPD and association with influenza vaccination.
BACKGROUND: We assessed the effects of an influenza season on patients with COPD. Data from 2,215 veterans in a multicenter, randomized, double-blind influenza vaccine efficacy study were analyzed for changes in spirometric and functional status, comparing patients with laboratory-documented influenza (LDI)-caused illness, non-LDI-caused respiratory illness, or no illness, and for association with influenza vaccination. METHODS: Patients received either IM trivalent inactivated influenza virus vaccine (TIV) plus intranasal trivalent, live attenuated, cold-adapted influenza virus vaccine (TC) or TIV plus intranasal placebo (TP). We performed spirometry, measured the chronic lung disease severity index (CLDSI) score to assess functional status and well-being, and tested for influenza virus infection. RESULTS: Worsening in FEV(1), percentage of predicted FEV(1), and CLDSI score (p < 0.001) was associated with acute respiratory illness in 585 illnesses including 94 LDI-caused illnesses. LDI-caused illness was more likely to be associated with worsening in FEV(1) and CLDSI score acutely than non-LDI-caused illness (p < 0.01). Logistic regression showed acute respiratory illness (odds ratio [OR], 1.78; 95% confidence limit [CL], 1.40 to 2.26) to be associated with worsening in CLDSI score, and receipt of TC (OR, 1.39; 95% CL, 1.10 to 1.74) and no illness (OR, 0.70; 95% CL, 0.53 to 0.91 for acute respiratory illness) to be associated with better CLDSI score at the end of the study. Hospitalization was more frequent in patients with acute respiratory illness (p < 0.0001). CONCLUSIONS: Acute respiratory illness was associated with increased health-care utilization and obstruction to airflow, and worse functional status and well-being. At the end of the study, receipt of TC was associated with improvement and acute respiratory illness was associated with worsening in functional status and well-being.
Aged↗
Clinical effectiveness of first and repeat influenza vaccination in adult and elderly diabetic patients.
OBJECTIVE: Influenza vaccine uptake remains low among the high-risk group of patients with diabetes, partly because of conflicting evidence regarding its potential benefits. We assessed the clinical effectiveness of influenza vaccination in adults with diabetes and specifically examined potential modification of effect by age and prior influenza vaccine uptake. RESEARCH DESIGN AND METHODS: The study was part of the Prevention of Influenza, Surveillance and Management (PRISMA) study, a nested case-control study conducted during the 1999-2000 influenza A epidemic, among 75,235 patients from primary care of any age recommended for vaccination. Among 9,238 adult patients with diabetes, 131 cases arose who were either hospitalized for diabetes dysregulation, acute respiratory disease, or cardiovascular disease and 61 cases who died, and we compared them with 1,561 control subjects. We evaluated the effect of (prior) influenza vaccination by means of logistic regression analysis controlling for age, sex, health insurance coverage, prior health care use, medication use, and comorbid conditions. RESULTS: Vaccination was associated with a 56% reduction in any complication (95% CI 36-70%), a 54% reduction in hospitalizations (26-71%), and 58% reduction in deaths (13-80%). Among study subjects aged 18-64 years, we observed somewhat higher reductions in the occurrence of any complication than among those aged >65 years (72 vs. 39%). In first-time vaccinated subjects, the primary end point was reduced by 47% (0.2-72%), and in those who received vaccination in the year before, the reduction was 58% (4-81%). CONCLUSIONS: Adults with type 2 diabetes, like other individuals from recognized risk groups, benefit considerably from influenza vaccination, and no difference in vaccine effectiveness was observed between first-time and repeat vaccination.
Adolescent↗
Improving influenza vaccination rates among adults.
Influenza remains an important cause of illness and death in this country. Even though we have safe and effective vaccines, vaccination rates among the elderly and other high-risk groups remain static and well below national goals. Health care providers can boost these vaccination rates by educating themselves, by recommending that their patients be vaccinated, and by implementing evidence-based strategies such as programs to remind themselves and patients to be vaccinated, to utilize standing orders for nurses or other qualified professionals to offer and administer vaccines, and to provide feedback on performance. We should also consider alternative paradigms for vaccine delivery, and be sure to be vaccinated ourselves.
Adolescent↗
Colds and influenza-like illnesses in university students: impact on health, academic and work performance, and health care use.
BACKGROUND: Upper respiratory tract illnesses (URIs) are a major cause of morbidity among adults, with substantial direct and indirect costs to society, but their impact among university students has not been well described. We sought to assess the impact of URIs (colds and influenza-like illnesses [ILIs]) on the health, academic and work performance, and health care use of university students. METHODS: This was a cohort study of college students at the University of Minnesota, Twin Cities campus (Minneapolis-St. Paul), who were recruited during October 2002 and followed up from November 2002 through April 2003. All 42,000 registered students were invited via e-mail to participate. Baseline information was obtained in October 2002. Monthly follow-up information about colds or ILIs was obtained for the period of November 2002 through April 2003. Data were collected by use of Internet-based questionnaires. RESULTS: Of 4919 volunteers, 3249 completed all follow-up surveys. The mean age was 22.7 years; 68% of the volunteers were female. Ninety-one percent had > or = 1 URI (83% had > or = 1 cold, and 36.7% had > or = 1 ILI). These URIs caused 6023 bed-days, 4263 missed school days, 3175 missed work days, and 45,219 days of illness. Of the cohort, 22.2% had > or = 1 health care visit, and 15.8% used antibiotics to treat a URI; 27.8% did poorly on a test and 46.3% did poorly on a class assignment. ILIs versus colds had a much greater impact on all parameters (e.g., general health level was 55%-60% lower with ILI vs. no URI and 33%-39% lower for colds vs. no URI; P < .001 for each). CONCLUSION: Colds and ILIs were common and associated with substantial morbidity in university students. Enhanced efforts to prevent and control URIs, especially influenza vaccination, could improve the health and well-being of the 17 million college and university students in this country.
Adult↗
Where adults reported receiving influenza vaccination in the United States.
BACKGROUND: Influenza vaccination coverage remains unacceptably low among persons aged > or =65 years and younger high-risk adults. This study assessed locations at which US adults receive influenza (flu) vaccinations and the relative roles that traditional and nontraditional vaccination settings play in influenza vaccine delivery. METHODS: We analyzed data on types of settings at which last flu shot was received, reported by adult respondents to the 1999 Behavioral Risk Factor Surveillance System, stratified by age group and medical condition. We used multivariable logistic regression to identify factors associated with nontraditional vaccination settings. RESULTS: In 1998-1999, reported influenza vaccination coverage was 19% for persons aged 18-49 years, 36% for persons aged 50-64 years, and 67% for persons aged > or =65 years. Seventy percent of flu shots received by persons aged > or =18 years were reportedly administered in doctors' offices and other traditional settings. Vaccination in nontraditional settings (eg, workplace, stores, community centers) was more likely for young, healthy, employed, white, college-educated adults who had not had a recent routine checkup. CONCLUSION: Physicians should offer vaccination services at every opportunity. Increasing access to vaccination services in nontraditional settings should be considered as another strategy in pursuit of national vaccination coverage objectives.
Adolescent↗
Health-related quality of life predicts future health care utilization and mortality in veterans with self-reported physician-diagnosed arthritis: the veterans arthritis quality of life study.
OBJECTIVE: To investigate whether health-related quality of life (HRQOL) measures predict health care utilization and mortality in a cohort of veterans with self-reported physician-diagnosed arthritis. METHODS: A cohort of veterans from the Upper Midwest Veterans Integrated Service Network (VISN) was mailed a self-administered questionnaire that was composed of the SF-36V (modified from SF-36 for use in veterans) and questions regarding demographics, current smoking status, limitation of activities of daily living (ADLs), and preexisting physician-diagnosed medical conditions, including arthritis. Within subjects reporting physician-diagnosed arthritis, we analyzed the associations between the SF-36V component summary scales (physical and mental component summary, PCS and MCS, respectively) and the occurrence of any hospitalization, number of hospitalizations, number of outpatient visits, and mortality, for the year after survey administration, using multivariable regression analyses. RESULTS: Of 34,440 survey responders who answered a question regarding arthritis, 18,464 (58%) subjects reported physician-diagnosed arthritis. Arthritic patients in the lowest tertile of PCS scores had significantly higher odds of any hospitalization (Odds ratio (OR) 1.49, 95% confidence interval (CI) [1.25-1.76]) and mortality (OR 1.69, 95% CI [1.18-2.42]), and a significantly higher number of hospitalizations/year (Rate ratio (RR) 1.09, 95% CI [1.05-1.13]) and outpatient visits/year (RR 1.07, 95% CI [1.03-1.11]). Arthritic patients in the lowest tertile of MCS scores had significantly higher odds of any hospitalization (OR 1.20, 95% CI [1.02-1.41]), mortality (OR 2.14, 95% CI [1.56-2.94]), and a significantly higher number of hospitalizations/year (RR 1.05, 95% CI [1.02-1.09]) and outpatient visits/year (RR 1.07, 95% CI [1.03-1.11]). CONCLUSIONS: HRQOL, as assessed by the SF-36V, predicts future inpatient and outpatient health care utilization and mortality in veterans with self-report of physician-diagnosed arthritis.
Activities of Daily Living↗
Health-related quality of life, functional impairment, and healthcare utilization by veterans: veterans' quality of life study.
OBJECTIVES: To describe the health status of veterans receiving care in a veterans integrated service network (VISN). DESIGN: Cross-sectional survey with prospective follow-up. SETTING: Former Upper Midwest VISN 13 (now a part of VISN 23), a regional Veterans Affairs (VA) network comprising five inpatient facilities and associated outpatient clinics. PARTICIPANTS: All veterans in VISN 13 who had at least one inpatient or outpatient encounter between October 1, 1997, and March 31, 1998. MEASUREMENTS: Health-related quality of life (HRQOL) assessed using subscales and component summaries from the 36-item short form for veterans (SF36-V), functional status assessed according to limitations in activities of daily living (ADLs), healthcare utilization assessed according to outpatient visits and hospitalizations, and death. RESULTS: Of 70,334 eligible veterans, 40,508 responded and reported baseline HRQOL significantly lower than that of the general U.S. population for the physical (35.6, P<.001) and mental (46.4, P<.001) component summary scores (PCS and MCS, respectively) of the SF36-V. Many reported complete inability or some difficulty in completing ADLs such as getting in and out of a chair (35.1%) and walking (45.3%). More than 58% indicated some degree of difficulty with at least one of the ADLs. In multivariate analysis, PCS and MCS were significantly associated with subsequent use of inpatient and outpatient care and with mortality. CONCLUSION: The low quality of life and associated high rates of health services utilization in VA patients imply a need for innovative strategies to improve the HRQOL and functional status of this population.
Aged↗
Influenza vaccination in the elderly: impact on hospitalisation and mortality.
Influenza causes substantial morbidity across the age spectrum. However, the elderly are especially vulnerable to the serious complications of influenza that might result in hospitalisation or death, and high rates of influenza-associated excess hospitalisation or death that exceed by several-fold the rates seen among most other age groups have consistently been observed in many countries and across many seasons. Thus, the elderly are included among the high priority groups for routine influenza vaccination by many national health authorities. Inactivated influenza virus vaccines are widely available across the globe and are safe and effective. Vaccination of elderly persons has been associated with significant reductions in hospitalisations for pneumonia and influenza as well as hospitalisations for other cardiopulmonary disorders and even cerebrovascular disease. Vaccination has also been associated with reductions in influenza-associated and all-cause mortality during influenza seasons. The benefits of vaccination extend not only to community-dwelling elderly but also to elderly who reside in nursing homes. Likewise, vaccination provides benefits to the very old and to elderly persons with underlying co-morbidities as well as to the healthy elderly. Despite the substantially increased risk for serious complications and impressive benefits from vaccination among the elderly, influenza vaccine utilisation remains below target rates for this group in nearly all countries. The need for improved prevention and control of influenza is recognised as a priority for the global community--both to reduce the morbidity and mortality associated with epidemic influenza and to prepare for the next pandemic. Enhancing vaccine delivery to elderly persons would represent important progress toward that goal.
Aged↗
Safety, efficacy, and effectiveness of live, attenuated, cold-adapted influenza vaccine in an indicated population aged 5-49 years.
BACKGROUND: Three important studies have supported licensure of live, attenuated, cold-adapted influenza vaccine (CAIV-T [FluMist; MedImmune Vaccines]): (1) a pediatric efficacy trial involving children 15-71 months of age, (2) a large safety study of medically attended events occurring among children 1-17 years of age, and (3) an effectiveness trial involving healthy working adults 18-64 years of age. METHODS: During the United States Food and Drug Administration (FDA) review for the approval of CAIV-T for use in healthy persons, additional subgroup analyses were conducted to evaluate the safety, efficacy, and effectiveness of the vaccine, by use of various age subsets not prespecified by the original protocols. CAIV-T is currently approved by the FDA for use in healthy persons 5-49 years of age. In this article, we present data from some of the aforementioned subanalyses. RESULTS: The efficacy of CAIV-T in children >or=5 years of age (age range of the children in year 1 of the study, 60-71 months; age range of the children in year 2 of the study, 60-83 months) was similar to that reported for the entire cohort in year 1 (90.6%; 95% confidence interval [CI], 70.3%-97.1%). In year 2 of the study, efficacy was 86.9% (95% CI, 70.8%-94.1%), despite the presence of antigenically drifted influenza type A/Sydney/5/97 (H3N2), which caused most illnesses that occurred in year 2. Safety outcomes for children 5-17 years of age revealed no significant difference between vaccine recipients and placebo recipients, with regard to acute respiratory events, acute gastrointestinal events, systemic bacterial infection, or rare events possibly related to influenza. Effectiveness among adults 18-49 years of age was similar to that reported for the entire cohort--for example, for occurrence of severe febrile illness, there was a 19.5% reduction (P=.02) in adults. CONCLUSIONS: The present reanalysis summarizes data on the indicated uses for CAIV-T in the indicated population aged 5-49 years.
Adaptation, Physiological↗
Development and validation of a clinical prediction rule for hospitalization due to pneumonia or influenza or death during influenza epidemics among community-dwelling elderly persons.
BACKGROUND: Uncertainties among health care providers and patients about the risk of serious influenza-associated complications and the potential benefits of vaccination may contribute to unsatisfactorily low influenza vaccination rates. To quantify the risk of serious outcomes (hospitalization due to pneumonia or influenza or death due to any cause) during influenza seasons, we developed a clinical prediction rule for the probability of hospitalization due to pneumonia or influenza or death among elderly persons. METHODS: We developed the clinical prediction rule using data from linked administrative databases in a cohort of 16,280 noninstitutionalized and unvaccinated elderly persons. Validation of the rule was conducted in 5 unvaccinated and 6 vaccinated cohorts, each consisting of >11,000 elderly members of 3 managed care organizations. Logistic regression was used to produce a prognostic score on the basis of the following predictors: age; sex; presence of pulmonary, cardiac, and renal disease; dementia or stroke and cancer; number of outpatient visits; and hospitalization due to pneumonia or influenza during the previous year. RESULTS: Reliability of the regression model was good (P=.65, by goodness-of-fit test), and it discriminated well between those who did and those who did not experience an outcome (area under the receiver-operating curve, 0.83; 95% confidence interval, 0.81-0.85). Validation revealed moderately lower but acceptable discriminating values (0.72-0.81). In the derivation cohort, the prognostic accuracy of the rule was high when a cutoff score for the upper 50th percentile was used: > or =10 of 1000 subjects with a score in the upper 50th percentile were predicted to have an outcome, and 89% of all outcomes were observed in this high-risk group, whereas <10 of 1000 subjects with a score in the lower 50th percentile were predicted to have an outcome, and only 11% of outcomes occurred in this group. Among unvaccinated subjects in the single-derivation cohort and the 11 validation cohorts combined, the outcome event rates were 35 events/1000 subjects in the higher-risk group and 6 events/1000 subjects in the lower-risk group. With vaccination, these event rates dropped by 15 events/1000 subjects and 2 events/1000 subjects, respectively. CONCLUSIONS: This prediction rule may be a useful tool to complement other age-based strategies, to further encourage vaccination, especially among those at the highest risk of serious complications due to influenza.
Aged↗
Adherence of mass vaccinators to timing guidelines for influenza vaccination.
BACKGROUND: With recent delays in influenza vaccine availability, practitioners have been encouraged to time vaccination activities to promote vaccination of high-priority groups first. This cross-sectional survey of persons vaccinated in nontraditional settings (NTS) by mass vaccinators was conducted to assess how effectively the mass vaccinators were able to implement these vaccination-timing guidelines. METHODS: In Minnesota, the Minnesota Visiting Nurse Agency (MVNA) is a major mass vaccinator in NTS. For the 2001-2002 vaccination season, MVNA developed several strategies designed to facilitate adherence to vaccination timing guidelines adopted by the Minnesota Department of Health. All persons vaccinated in the MVNA NTS clinics from October 2001 through December 2001 were surveyed in order to evaluate whether they were in a high-priority group and whether the timing of their vaccinations coincided with the timing promoted in the guidelines. RESULTS: A total of 46,174 of the 145,947 people vaccinated by the MVNA were vaccinated between October 14 and October 28, 2001, the time period designated for vaccination of high-priority groups. Of these, 41,143 (89%) responded to the priority group question and 27,211 (66%) indicated that they were in one of the targeted groups, including more than 19,000 Medicare recipients. At sites targeting senior citizens, more than 92% of initial vaccine recipients were in a targeted group. Overall, 48.4% of persons vaccinated at any time during the vaccination season were in a high-priority group. CONCLUSIONS: Mass vaccinators can successfully implement influenza vaccination timing guidelines in NTS.
Cross-Sectional Studies↗
Influence of clinical case definitions with differing levels of sensitivity and specificity on estimates of the relative and absolute health benefits of influenza vaccination among healthy working adults and implications for economic analyses.
Clinical illness case definitions for influenza and methods used to define influenza seasons can vary substantially from study to study. These differences often result in differing levels of sensitivity, specificity and positive predictive value for the case definitions used. We explored the implications of different case definitions and outcome periods on estimates of influenza vaccine effectiveness and cost benefit by conducting additional analyses of data collected from a randomized, double blind, placebo controlled trial of the trivalent, intranasal, live attenuated influenza virus vaccine in healthy working adults. Febrile upper respiratory tract illnesses occurring during the peak influenza period was identified as the most specific clinical case definition expected to have the highest positive predictive value for true influenza whereas events occurring on a day with any symptom occurring during the entire outcome period was identified as the most sensitive clinical case definition with the lowest positive predictive value for influenza. As expected, the former provided the highest estimates of vaccine effectiveness (28.4% reduction in work loss days, 24.6% reduction in days with impaired productivity and 40.9% reduction in days with health care provider visits) but the lowest estimates of absolute reductions in events (42.4 work loss days prevented per 1000, 79.0 impaired productivity days per 1000, and 16.5 days with health care provider visits per 1000). On the other hand, events on days with any symptom during the entire outcome period provided the lowest estimates of vaccine effectiveness (18% reduction in work loss days, 18% reduction in days with impaired productivity, and 13% reduction in days with health care provider visits) but the highest estimates of absolute reductions in events (186.4 work loss days per 1000, 271.5 impaired productivity days per 1000, and 44.8 days with health care provider visits per 1000). When applied to a cost benefit analysis, the more specific case definition provided a break even cost for vaccination of US$ 6.58 whereas the more sensitive case definition provided a break even cost for vaccination of US$ 43.07. Clearly the latter combination is most appropriate when trying to assess the total population level impact of a vaccine preventable disease and the potential cost effectiveness of vaccination whereas the former may be most appropriate for assessing whether the vaccine actually works. The definitions of clinical influenza illness and outcome periods should be selected to match the study question.
Adult↗
Work-site-based influenza vaccination in healthcare and non-healthcare settings.
OBJECTIVE: To better understand work-site-based programs for influenza vaccination. DESIGN: Self-administered, mailed questionnaire. SETTING: Healthcare and non-healthcare companies. PARTICIPANTS: Random sample of 2000 members of the American Association of Occupational Health Nurses. RESULTS: The response rate was 55%, and 88% of the respondents were employed by companies sponsoring work-site influenza vaccination. Thirty-two percent of respondents worked for healthcare and healthcare-related services companies. Healthcare companies were more likely to sponsor worksite-based vaccination (94% vs 85%; P < .0001) compared with non-healthcare companies. Healthcare companies were also more likely to encourage vaccination of high-risk employees (70% vs 55%; P < .0001) and cover its cost (86% vs 61%; P < .0001). Multivariate logistic regression was used to determine factors associated with highly successful vaccination. Being a healthcare-related company (OR, 2.1; CI95, 1.4-3.2; P < .0001), employers covering the vaccination cost (OR, 3.1; CI95, 1.4-6.6; P = .004), having more experience with work-site vaccination (OR, 1.6; CI95, 1.0-2.4; P = .036), and management encouraging vaccination (OR, 2.6; CI95, 1.4-4.9; P = .002) were associated with highly successful programs. CONCLUSIONS: Most of the occupational health nurses surveyed work for employers sponsoring work-site vaccination, and 32% were employed by healthcare and related services companies. Healthcare companies were more likely to sponsor worksite-based vaccination and to vaccinate most of their employees; however, only 18% had vaccination rates higher than 50%. Strategies need to be developed to increase vaccination rates so that benefits of vaccination can be realized by employers and employees.
Adolescent↗