Paula L. Sullivan, DHSc, MSN, APRN

Abstract

Since 1981 the Centers for Disease Control and Prevention has recommended that healthcare workers receive vaccination against influenza in an effort to reduce transmission of the virus to their colleagues and to the vulnerable people in their care. To date inadequate progress has been made in terms of increasing yearly healthcare worker influenza vaccination rates. In this article the author reviews influenza epidemiology, prevention, vaccination, and evidence related to vaccination benefits; and discusses the elimination of barriers to vaccination. Voluntary interventions to increase vaccination rates are described. The benefits and challenges of mandatory vaccination, including both mandating of individual vaccination and institutional vaccination programs are reviewed. In the conclusion, the author advocates for rejecting mandatory individual vaccination and supporting institutional mandates that protect the right of the individual to decline vaccination for religious, medical, or philosophical reasons.

Citation: Sullivan, P., (Nov. 2, 2009) "Influenza Vaccination in Healthcare Workers: Should it be Mandatory?" OJIN: The Online Journal of Issues in Nursing Vol. 15 No. 1.

Key words: barriers to vaccination, communicable disease, influenza, influenza vaccine, influenza transmission by healthcare personnel, institutional vaccination programs, patient safety, mandatory vaccination, voluntary vaccination

DOI: 10.3912/OJIN.Vol15No01PPT03

Influenza, an infectious disease that occurs annually in temperate regions around the world, affects an estimated 5-15% of the world’s population and results in 500,000 deaths annually (World Health Organization, [WHO], 2009b). In the United States (US), between 1979 and 2001, an average of 226,000 persons were hospitalized and 36,000 died each year as a result of complications from influenza (Centers for Disease Control and Prevention [CDC], 2007). Cross-transmission of influenza infection from healthcare workers (HCW) to patients has been described in various clinical settings, including long-term-care facilities (LTCF), oncology units, solid transplant units, neonatal intensive care units (NICU), and pediatric units (Malavaud et al., 2001; Munoz et al., 1999; Slinger & Dennis, 2002; Weinstock et al., 2000).

Since 1981, the CDC (2006) has recommended that HCWs receive vaccination against influenza in an effort to reduce transmission of the virus to their colleagues and to the vulnerable people in their care. To date, inadequate progress has been made in terms of increasing HCW influenza vaccination rates among HCWs which remain less than 50% (CDC, 2008). Healthcare workers have identified a number of barriers to vaccination. Although multi-faceted programs that eliminate these barriers and support voluntary vaccination have been effective in increasing vaccination rates, these programs are a recent phenomenon, and have not been widespread. Healthcare agencies are now considering mandatory influenza vaccination for their healthcare providers.

Given the seriousness of the disease, its potential for cross-transmission, and the lack of HCW voluntary compliance with vaccination, Poland, Tosh, and Jacobson (2005) have argued that mandatory vaccination is ethically warranted. Backer (2006) and also Poland and Jacobson (2007) have supported mandatory influenza vaccination, likening mandatory influenza vaccination to laws mandating Hepatitis B programs. It is important to note, however, that Hepatitis B vaccination is not mandated for individual HCWs, but rather institutions are mandated to offer the vaccine to all persons with the potential for blood exposures (Occupational Health and Safety Administration [OSHA], 1991). Currently HCWs maintain the right to decline Hepatitis B vaccination (OSHA, 2009). Others oppose mandating individual vaccination of HCW's, describing it as punitive. They call for implementing barrier-eliminating strategies as a means of improving vaccination rates, while respecting the right of HCWs to decline vaccination (American College of Occupational and Environmental Medicine [ACOEM], 2005; American Nurses Association [ANA], 2006; CDC, 2008; National Foundation of Infectious Diseases, [NFID], 2008).

While it is clear that increasing influenza vaccination in HCWs is important, it is less clear on how best to achieve this goal. This article will address the seasonal prevention of influenza by presenting various viewpoints on this controversial issue. The author will review influenza epidemiology, prevention, vaccination, and evidence related to the benefits of vaccination, and discuss the elimination of barriers to vaccination. Voluntary interventions to increase vaccination rates will be described. Benefits and challenges of mandating both individual vaccination and institutional vaccination programs will be reviewed. The author will conclude by advocating for rejecting the mandating of individual vaccination and supporting the requirement that institutions be mandated to offer programs aimed at eliminating the barriers to voluntary immunization.

The author searched Medline and CINAHL randomized controlled studies (RCT), case studies, case reports, editorials, and expert opinions, using the keywords: influenza vaccine, healthcare personnel, healthcare workers, patient safety, transmission, communicable disease, mandatory vaccination, and barriers to vaccination in preparing this article. Initially the time frame for the search was 2001-2009; but due to the limited number of available studies, the search was expanded back to 1990. Secondary resources included the Cochrane Database and the Trip Database. In addition epidemiological and survey data were retrieved from U.S. regulatory agencies and professional organizations, including the CDC, The Joint Commission (TJC), the U.S. Department of Health and Human Services (USDHHS), NFID, ANA, the Association of Professionals in Infection Control (APIC), and also the international World Health Organization.

Epidemiology

Contagiousness begins one day prior to the development of symptoms... Influenza is a viral illness easily transmitted from person to person through air droplets passed by sneezing, coughing, and a lack of adherence to appropriate handwashing guidelines. Influenza generally appears during cold-weather seasons. The incubation period ranges from 1-4 days. Contagiousness begins one day prior to the development of symptoms, and can last as long as 5 days in adults and 10 days in children (CDC, 2008). Symptoms include cough, fever, chills, headache, and myalgias. The majority of infected persons will recover in approximately 3-7 days. The less fortunate will develop complications that require hospitalizations, most commonly pneumonia; and some will die of these complications. At greatest risk of developing complications are adults > 65 years of age, children < 2 years, and those with medical conditions that increase the likelihood of complications (CDC). Ninety percent of influenza deaths in the US occur in persons > 65 years old (CDC).

Prevention of Influenza

The primary and most effective method of symptom reduction and prevention of influenza is vaccination. The primary and most effective method of symptom reduction and prevention of influenza is vaccination. Because of a process known as antigenic drift, in which the influenza virus undergoes a mutation that strengthens its resistance to the vaccine, minor changes in the make-up of the vaccine are required annually (CDC, 2008). Even if a drift in the virus occurs, the vaccine continues to provide some protection against influenza. This is not true in the case of antigenic shift, which results in the emergence of new influenza viruses for which there is little protection and no vaccine. Antigenic shift often results in an influenza pandemic (CDC). The current influenza A(nH1N1) pandemic of 2009 is one example of antigenic shift. As of October 30, 2009, the WHO (2009a) reported 440, 000 laboratory-confirmed cases of A(nH1N1) in 60 countries, resulting in 5,712 deaths. How long the pandemic will last is uncertain. Final data on morbidity and mortality will be determined once the pandemic subsides. A second example of a pandemic that had serious global consequences in terms of morbidity and mortality was the great influenza outbreak of 1918-1919, which resulted in the deaths of 30-100 million people worldwide and 675,000 deaths in the US (USDHHS, 2008). Despite the limited vaccine to prevent pandemics, it is believed that education aimed at improving the understanding of influenza, enhanced infection control (IC) practices, and the availability and use of antiviral medications will today result in a decreased likelihood of disease transmission, and prevent the catastrophic results of past pandemics (USDHHS, NFID, 2008).

Influenza Vaccination

This section will describe the 2008-2009 seasonal flu general influenza vaccine, vaccination rates, and the effectiveness of the vaccination. It will also address possible side effects related to influenza vaccination.

Current (2009) Influenza Vaccine

The most common vaccine is the injectable trivalent inactivated vaccine (TIV). Since 2003, a live attenuated vaccine (LAIV) has been approved for intranasal use in healthy, non-pregnant persons who are between 5 and 49 years of age (CDC, 2008). Beginning with the 2008-2009 flu season the CDC approved and recommended either TIV or LAIV for healthy persons 2 to 49 years of age. Some populations that remain specifically targeted for vaccination with TIV are: (a) children < 5 years of age with reactive airway disease, (b) all adults > 50 years, (c) pregnant women, (d) adults of all ages with chronic health problems (e) family members of persons at high-risk for severe complications of influenza, and (f) HCWs.

Because of the theoretical risk that the influenza virus can be transmitted following vaccination with LAIV, TIV is the preferred choice for HCWs (CDC, 2008). HCWs who choose vaccination with LAIV must be restricted from caring for immunocompromised patients for seven days (CDC). Optimal influenza vaccination time is from September through December, but it may be given throughout the entire flu season.

Influenza Vaccination Rates

Efforts to increase rates of influenza vaccination have been successful in some age groups, particularly in the chronically ill and infirm adults ages 65 years or older (CDC, 2007). However, in adults between the ages of 18 and 64 years of age, including those with at least one risk factor for complications, the rates have shown little improvement from a baseline rate in 1998 (32% in 2007 vs. 26% in 1998) as reported by Healthy People 2010; these rates are well below the targeted goal of 90% of the entire population (USDHHS, 2001). Only 42% of HCWs received the vaccine during the 2006-2007 flu season (CDC). This is concerning given one study that identified laboratory-confirmed influenza in 20% of unvaccinated HCWs in a LTCF during one flu season (Carman et al., 2000), and evidence that viral shedding can occur one day before symptoms appear (CDC). Clarifying the implications of low HCW vaccination rates on patient care may help determine the need for, and the type of strategies that may lead to enhanced vaccine acceptance in this population.

Vaccine Effectiveness

The WHO, in collaboration with the U.S. Federal Drug Administration, is responsible for determining the strain for upcoming seasons. When matched to the strain of circulating viruses, TIV has demonstrated efficacy in preventing influenza illness in healthy adults < 65 years of age (70%-90%), non-institutionalized adults aged > 60 (58%), and children between the ages of one and fifteen years (77-91%) (CDC, 2007). Although less effective in the institutionalized elderly > 65 years of age (20-40%), it prevents 80% of influenza-related deaths in this age group (CDC). Efficacy rates for LAIV were reported to be 49% in healthy adults ages 18-64, and 94% in children between 15-71 months old (CDC). An interesting example of the benefit of a mismatched vaccination in providing some protection was demonstrated during the 2007-2008 season when the vaccine still had an overall protection rate of 44% (CDC, 2008).

Side Effects of Influenza Vaccine

Vaccination with LAIV may result in mild nasal congestion, sore throat, and headache, but serious SEs are rare. Serious side effects (SEs) of influenza vaccine are uncommon. The CDC (2008) reported the most common SEs of TIV as a mild, local tenderness at the site of injection affecting approximately 10-64% of recipients. Persons receiving their first vaccination may experience mild systemic symptoms including fever, malaise, and myalgia lasting one to two days. One RCT conducted to compare SEs of TIV in 841 healthy working adults, failed to document a difference between the experimental and placebo groups (34.1% vs. 35.2%; p = .78) in terms of developing fever, malaise, fatigue, or headaches (Nichol et al. 1996). However, a localized reaction at the injection site was more likely to occur in the experimental group compared with the placebo group (63.8% vs. 24.1%; p = .001). The authors concluded that TIV was not associated with a higher rate of systemic symptoms when compared to placebo. Vaccination with LAIV may result in mild nasal congestion, sore throat, and headache, but serious SEs are rare (CDC).

The most serious and concerning SE associated with influenza vaccine is Guillain-Barre Syndrome (GBS). GBS is a neurological syndrome that results in peripheral muscle weakness and paralysis. An increase in the incidence of GBS was observed in vaccinated adults following immunization with the swine flu vaccine during the 1976-1977 (CDC, 2007) and with seasonal vaccination during the 1992-1993 and 1993-1994 seasons (Lasky et al. 1998). Although the increase was not statistically significant, researchers could not rule out a causal relationship.

Evidence Related to Vaccination Benefits

Studies document the ease at which the influenza virus is transmitted in healthcare settings. Munoz et al. (1999) identified nurses as the likely source of an outbreak in a NICU that resulted in the death of one neonate. Although influenza infection in the nursing staff was not laboratory confirmed, influenza-like illness (ILI) was diagnosed in four nurses who were absent from work at the onset of the outbreak. The vaccination rate for the nursing staff was 5%. Based only upon the low vaccination rate and work absences of staff nurses, the researchers concluded that nurses were the probable cause of the outbreak.

Studies document the ease at which the influenza virus is transmitted in healthcare settings. Nurses were also found to be the most likely vectors for a nosocomial outbreak of influenza in a 12-bed, solid-transplant unit that resulted in influenza among four patients and three of the 27 nurses assigned to the unit (Malavaud et al., 2001). None of the affected patients or nurses had been vaccinated. Family and friends were eliminated as sources of infection when it was identified that no patients had had visitors. This fact, along with a nurse being identified as the index case, and the definitive incubation period for all cases, led researchers to conclude that all three nurses contributed to the outbreak.

The paragraphs below will summarize various studies documenting the effectiveness of vaccination in preventing influenza. Some of these reports offer suggestive evidence, others offer only indeterminate evidence. Some experts have concluded that this evidence provides an adequate basis for mandating that all HCSs be vaccinated; others have questioned this conclusion.

Suggestive Evidence Related to Vaccination Effectiveness

In a RCT conducted to determine the effect of HCW vaccination rates on mortality in elderly residents of long-term-care facilities, Potter et al. (1997) identified a statistically significant reduction of the mortality rate from 17% to 10% (odds ration [OR], 0.56; 95% confidence interval [CI], 0.40-0.80), indicating a positive association between vaccination and mortality when staff vaccinations were increased. This assumption was further supported by researchers at the University of Virginia Health System who identified a statistically significant decrease in nosocomial transmission of influenza disease with increased HCW vaccination rates (p = .001) (Salgado, Giannetta, Hayden, & Farr, 2004).

Researchers documented a positive correlation between HCW vaccination and morbidity and mortality during the first season, but not the second season, in a RCT to determine the effectiveness of HCW vaccination on the mortality and morbidity of nursing home residents during the flu seasons of  2003-2004 and 2004-2005 (Hayward et al., 2006). A significant difference in mortality between the two groups was also documented (Hayward et al.). Utilization of the vaccine among HCWs in the intervention group (vaccine offered) vs. the control group (no vaccine offered) resulted in vaccination rates of 48.2% (2003-2004) and 43.2% (2004-2005) in the intervention group vs. 5.9% and 3.5% respectively in the control group. A significant difference in the rates of ILI (p = .004) and hospitalizations (p=0.009) occurred between the residents cared for by nurses in the intervention group as compared to residents cared for by nurses in the control group. The low incidence of influenza disease in the 2004-2005 was the likely reason that no difference in morbidity and mortality was found during the second season studied. It should be noted that laboratory confirmation of influenza illness was not presented in the findings, and evidence of a mild antigenic shift in the circulating virus occurred during both years.

Carman et al. (2000) identified a significant difference in mortality rates between long-term-care hospitals that routinely provided influenza vaccine to staff (13.6%), as compared to those that did not (22.4%) (OR 0.58 [95% CI 0.40-0.84] (p = .014). These differences in mortality rates were confirmed in a systematic review that pooled the findings of two studies: Carmen, 2000 and Potter et al., 1997 (in Jordan et al. 2004), but were rejected in a Cochran review citing methodological-design problems that included selection bias, failure to provide laboratory confirmed illness, unknown vaccine match, and the lack of documented HCW vaccination rates (Thomas, Jefferson, Demicheli, & Rivetti, 2006). Researchers did identify a reduction in ILI complications in patients residing in the LTCFs, but only when both staff and patients were vaccinated (VE 86%, 95% CI 40% to 97%) (Thomas et al.).

Indeterminate Evidence Related to Vaccination Effectiveness

Additional studies have indicated that low staff-vaccination rates may be a possible source of morbidity and mortality. However, findings from these studies are classified as indeterminate because other factors were indicated as the primary cause of these nosocomial outbreaks. During the 1991-1992 flu season, 65 of 337 nursing home residents (19%) were diagnosed with influenza, despite a resident vaccination rate of 88% (CDC, 1992). Of those afflicted, 53 residents developed complications that resulted in the hospitalization for 19 residents and death for two residents. The vaccine efficacy for the elderly residents was determined to be 43%. The vaccination rates and vaccine efficacy for employees were 10% and 86% respectively. The incidence of HCW illness was not discussed, nor were they implicated as the source of infection in the outbreak. These researchers concluded that diminished vaccine efficacy in the elderly warrants the vaccination of HCWs as a means to decrease the potential cross-transmission of influenza from HCW to the elderly.

Coles, Balzano, and Morse (1992) reported similar findings in a retrospective cohort study of influenza in elderly residents of a LTCF. The vaccination rate for the residents was 90% as compared to 10% in the staff, and vaccine efficacy was 21% and 45% respectively. Neither illness nor vaccination rates among visitors and family were evaluated. Thirty-seven residents and 18 staff became symptomatic for influenza (attack rate 30% vs.12%). Laboratory evidence of cross-transmission from HCW to patients was lacking, and antigenic drift was identified as the major factor in the outbreak.

In a retrospective study of the incidence of influenza in a pediatric hospital covering a five-year period, Slinger and Dennis (2002) identified HCWs as one possible source of nosocomial infection, despite being unable to confirm that such a transmission occurred. Cross-transmission between roommates was confirmed. This study did not identify influenza illness or vaccination rates among HCWs at the time of the outbreak, but concluded that given the traditionally low vaccination rates of HCWs at the facility, it was reasonable to consider them as possible sources.

Patient-to-patient transmission was identified as the cause of a nosocomial outbreak of influenza in a hospital oncology unit that infected 19 patients and led to three deaths (Schepetiuk, Papanaoum, & Qiao, 1998). Although researchers believed that the low vaccination rate among staff, along with the concurrent illness of two staff members with ILI, most likely contributed to the outbreak, data was insufficient to confirm this. Patient-to-patient transmission was also suspected in one outbreak in a bone marrow transplant unit that resulted in unconfirmed disease in five employees (Weinstock et al., 2000). The low vaccination rate among staff became the driving force behind an enhanced vaccination program the following year that resulted in improved vaccination rates and decreased nosocomial influenza infection.

Understanding the barriers that prevent HCWs from accepting influenza vaccination is a necessary step in promoting and improving vaccination rates. Results from these studies identify the currently low HCW influenza vaccination rates, and provide evidence that cross-transmission of influenza disease from HCW-to-patient, and patient-to-patient can occur during institutionalization. However, little attention in these studies was given to other potential sources of disease transmission. Although family and friends were ruled out as vectors in one study (Malavaud et al. 2001), no other study provided data on family and friend vaccination or illness status, despite the very real possibility that they could have been the sources of transmission.

Additionally, few studies that documented nosocomial transmission of influenza addressed infection control practices. Yet, a failure to comply with recommended IC protocols has been identified as the most likely reason for work-related A(nH1N1) infection in HCWs (CDC, 2009). Global healthcare workers compliance with handwashing was found to average 38.7% (WHO, 2009c).

Without data that supports HCW vaccination as the single most important factor in preventing cross-transmission, it would seem premature to single HCWs out for mandated vaccination, as opposed to mandating institutional action to promote and provide vaccination to HCWs. It is clear that HCW vaccination rates are low. Understanding the barriers that prevent HCWs from accepting influenza vaccination is a necessary step in promoting and improving vaccination rates.

Elimination of Barriers to Vaccination

Several cross-sectional studies examined the barriers to HCW influenza vaccination. Commonly cited reasons include: (a) lack of accessibility, (b) dislike of injections, (c) fear of SEs (including getting the flu), (d) forgetting, (e) lack of time, (f) lack of awareness of the vaccine, (g) disbelief in vaccine effectiveness, (h) not thinking it was needed, and (i) believing one doesn’t get the flu (Canning, Phillips, & Allsup, 2005; Christini, Shutt, & Byers, 2007; Mah et al., 2005, Martinello, Jones, & Topol, 2003).

In one study Mah et al. (2005) surveyed 363 staff members in a Canadian cancer center to assess their attitudes toward influenza vaccination. Although 74% of respondents agreed that vaccine programs were beneficial, only 162 reported being vaccinated at least once in the five years prior to the survey. Of the 45% who had not been vaccinated, the most commonly cited reason reported was disbelief that the vaccine was effective. Nineteen percent believed that the vaccine would cause them harm.

In another study, a correlation between influenza vaccine acceptance and HCW knowledge was identified using a cross-sectional survey that assessed participants’ knowledge of influenza (Martinello et al., 2003). Statistical analysis documented a knowledge deficit in nurses, but not in physicians. A statistically significant difference in vaccination rates between nurses and physicians (62% vs. 82%; p=.0009) was reported, suggesting that knowledge deficit was a barrier to vaccine acceptance among nurses (Martinello et al.). This correlation was supported by Canning et al. (2005) who attributed poor vaccination rates in HCW participants to lack of basic knowledge about the benefits and risks of influenza vaccination.

Christini et al. (2007) reported that enhanced knowledge about the vaccine contributed to a higher vaccination rate in most physician specialties as compared to RNs (69% vs. 46%). In this study, however, surgeons reported a vaccination rate of only 43%. The reason for this low rate among surgeons was not identified. Participants in this study did report the lack of time, doubts about vaccine effectiveness, and fear of SEs as the most common reasons for declining vaccination. The researchers concluded that the program was effective, but determined that different healthcare groups (e.g. surgeons) will require different approaches to strengthen vaccination programs.

Given the seriousness of influenza mortality and morbidity in certain populations groups, the potential for cross-transmission of influenza from HCWs to patients, and the traditionally low rates of vaccine acceptance among HCWs, the importance of addressing these misconceptions and concerns cannot be understated. Identifying proven strategies that lead to increased HCW vaccination rates is necessary.

Voluntary Interventions to Increase Vaccination Rates

International institutions have also attempted to increase vaccination rates through institutional intervention. Successful voluntary programs that target staff vaccination have been implemented by various healthcare organizations. With improved education and vaccine accessibility, staff vaccination rates at the Mayo Clinic across four flu seasons (1999-2004) increased from a baseline of 53.6% to 75%, while the Minneapolis Veterans Affairs Medical Center improved their rates from a baseline of 25% in 1985 to 65% during the 2003-2004 flu season (CDC, 2005).

At the California Health Department a convenience sample of 67 nursing homes (response rate 95%) took part in a controlled study to evaluate the effectiveness of planned educational interventions and increased accessibility of influenza vaccine for employees. Their findings supported effectiveness when both interventions were implemented (53% coverage; adjusted odds ratio [AOR] = 3.54; 95% CI = 2.17-5.72) and with increased vaccine accessibility alone (45%; AOR-2.28; CI =1.30-3.98). However, the educational intervention alone format did not result in increased vaccination rates (34%; AOR =1.31; CI =0.76-2.25) (CDC, 2005).

Other institutions, too, have increased their HCW vaccination rates using a variety of strategies. The Memorial Sloan Kettering Cancer Institute successfully increased vaccination rates of HCWs on the bone marrow transplant unit 12% in one year, from 42% to 58% by improving accessibility (Weinstock et al., 2000). Qureshi, Hughes, Murphy and Primrose (2004) reported increased vaccination rates [odds ratio (OR =11.01; 95% CI = 2.13-56.80) p = .0001] with successful implementation of a program utilizing visual aids, e.g., posters and pamphlets. St. Joseph Hospital in Wisconsin achieved a staff vaccination rate of 83% when vaccination was combined with the annual tuberculosis screening (APIC, 2007). St. Jude Children’s hospital in Memphis, TN, known for its care of children with high-risk diseases, improved influenza vaccination rates in their HCWs from 40% to 80% with a program that included a pre-campaign marketing of meetings, posters, newsletters, and 24/7 vaccine accessibility for all staff (McCullers, Speck, Williams, Liang, & Joseph, 2006). Follow-up efforts in this study included solicitation of individual feedback, a strategy that was found to positively influence vaccine acceptance. Within three years, vaccination rates reached 96% (NFID, 2008).

Findings from these studies indicate that initiatives designed to increase voluntary influenza vaccination rates in HCW's are effective, especially when they are readily accessible and educational resources are provided. International institutions have also attempted to increase vaccination rates through institutional intervention. Communication to staff using informational posters and leaflets resulted in a statistically significant improvement in vaccination rates in employees in a Madrid hospital over three flu seasons (2001-2002, 2002-2003, 2003-2004) (de Juanes et al., 2007). Rates improved from a baseline of 16% the first year to 21% and 40% (2002-2003 and 2003-2004, respectively) (p = .01). Researchers identified an ongoing need for new strategies that would lead to further increases in vaccination. A major limitation of the program was its failure to address the issue of vaccine accessibility. Vaccination was available in one hospital department only, thus limiting staff accessibility to the vaccine. Given the success of previously mentioned programs that utilized mobile carts, the vaccination rates in this study may have been higher had this additional intervention been used.

Findings from these studies indicate that initiatives designed to increase voluntary influenza vaccination rates in HCW's are effective, especially when they are readily accessible and educational resources are provided. However, overall HCW vaccination rates remain low, and there is a growing recognition that additional actions to increase vaccination rates are necessary. In recent years, two different approaches have been advocated. A discussion of both strategies follows.

Mandatory Vaccination