Immunization and
Infectious Diseases

Prevent disease, disability, and death from infectious diseases, including vaccine-preventable diseases.

Infectious diseases remain major causes of illness, disability, and death. Moreover, new infectious agents and diseases are being detected, and some diseases considered under control have reemerged in recent years. In addition, antimicrobial resistance is evolving rapidly in a variety of hospital- and community-acquired infections. These trends suggest that many challenges still exist in the prevention and control of infectious diseases.

Issues

Between 1980 and 1992, the number of deaths from infectious diseases rose 58 percent in the United States.[1] Even when human immunodeficiency virus (HIV)-associated diagnoses are removed, deaths from infectious diseases still increased 22 percent during this period. (See Focus Area 13. HIV.) Considered as a group, three infectious diseases—pneumonia, influenza, and HIV infection—constituted the fifth leading cause of death in the United States in 1997.1

The direct and indirect costs of infectious diseases are significant. Every hospital-acquired infection adds an average of $2,100 to a hospital bill. Bloodstream infections result in an average of $3,517 in additional hospital charges per infected patient because the patient stay averages an additional 7 days. A typical case of Lyme disease diagnosed in the early stages incurs about $174 in direct medical treatment costs. Delayed diagnosis and treatment, however, can result in complications that cost from $2,228 to $6,724 per patient in direct medical costs in the first year alone.[2]

Infectious diseases also must be considered in a global context. Increases in international travel, importation of foods, inappropriate use of antibiotics on humans and animals, and environmental changes multiply the potential for worldwide epidemics of all types of infectious diseases. International cooperation and collaboration on disease surveillance, response, research, and training are essential to prevent or control these epidemics. Actions taken to improve health in one country affect the health of people worldwide.

Vaccines. Vaccines are biological substances that interact with the person’s immune system to produce an immune response identical to that produced by the natural infection.

Vaccines can prevent the debilitating and, in some cases, fatal effects of infectious diseases. Vaccines help to eliminate the illness and disability of polio,[3] measles, and rubella.[4] However, the organisms that cause these diseases have not disappeared. Rather, they have receded and will reemerge if the vaccination coverage drops. The serious health burden of vaccine-preventable diseases (VPDs) is evident from the measles resurgence of 1989 to 1991, resulting in more than 55,000 cases, 11,000 hospitalizations, 120 deaths, and $100 million in direct medical care costs.[5], [6], [7], [8]

Vaccines protect more than the vaccinated individual. They also protect society. When vaccination levels in a community are high, the few who cannot be vaccinated—such as young children and persons with contraindications to vaccination—often are indirectly protected because of group immunity (in other words, they live among vaccinated persons who may offer protection from exposure to disease).

Vaccines provide significant cost benefits. Three childhood vaccines—diphtheria, tetanus toxoids, and acellular pertussis vaccine (DTaP); measles, mumps, and rubella vaccine (MMR); and Haemophilus influenzae type b (Hib) vaccine—result in substantial direct medical savings for each dollar spent to vaccinate children against these diseases. Varicella vaccine saves roughly 90 cents in direct medical costs for every dollar invested. Consideration of indirect savings—prevention of work loss by parents to care for ill children and prevention of death and therefore lost earnings from disability—shows that vaccines routinely recommended for children are highly cost saving. Savings range from $24 for every dollar spent on DTaP to $2 for the more recently approved Hib vaccine.[9]

Trends

Significant progress has been made in reducing indigenous (not imported) cases of VPDs. The occurrence of many VPDs is at or near record-low levels. Most diseases have been reduced by more than 95 percent from peak prevaccine levels.[10]

In 1998, overall vaccination coverage for children aged 19 to 35 months was at record-high levels.[11] Antigen-specific rates have shown striking progress since 1992.[12] For example, coverage for three or more doses of polio vaccine increased from 72 percent to 91 percent, and coverage for three or more doses of Hib vaccine increased from 28 percent to 93 percent. Significant achievements were made among racial and ethnic groups in that most of the 1996 goals for the Childhood Immunization Initiative were met for individual vaccines.[13] Since 1989, vaccination requirements have been expanded for schools and day care settings.12 As of the 1998–99 school year, all States required vaccination against diphtheria, measles, and polio. Similarly, all States and the District of Columbia now require vaccination for children in day care.[14]

In 1996, a vaccine against hepatitis A virus (HAV) was licensed that has the potential to reduce the health burden of this disease. The vaccine is now recommended primarily for high-risk groups. To decrease HAV transmission, universal vaccination was recommended in 1999 for children who lived in States where the rate of new cases was greater than two times the national average.[15]

Financing for childhood vaccinations has improved significantly as a result of two initiatives—Vaccines for Children and the State Children’s Health Insurance Program (SCHIP)—that cover children on Medicaid, uninsured children, and American Indian and Alaska Native children. Underinsured children who receive vaccinations at federally qualified health centers also are covered. Because they promote free vaccines for children, these programs eliminate vaccine cost as a barrier to childhood vaccination. Also, the Public Health Service Act, Section 317 immunization grant program and State funds provide free vaccines for children not covered by other programs.

Vaccination rates among persons aged 65 years and older continued to increase over the decade. Influenza vaccine coverage rates were up from 33 percent in 1989 to 64 percent in 1998, and pneumococcal vaccine coverage rates were up from 15 percent to 46 percent. Despite these increases, coverage rates for certain racial and ethnic groups remain substantially below the general population.[16]

Invasive diseases invade the bloodstream and cause distant infection. The most common types of invasive disease caused by Hib are meningitis, epiglottitis, pneumonia, certain types of arthritis, and cellulitis. Conjugate vaccines—licensed in 1990 for use beginning at age 2 months—are highly effective in protecting against Hib meningitis and other invasive diseases caused by Hib. These vaccines also interrupt spread of the disease-causing organism by affecting the organism’s nasopharyngeal colonization. New cases of Hib meningitis declined by 96 percent from 1987 to 1995.[17] During that period, bacterial meningitis caused by one of the five leading agents (Haemophilus influenzae, Streptococcus pneumoniae, Neisseria meningitidis, group B Streptococcus [GBS], and Listeria monocytogenes) fell by 55 percent. Bacterial meningitis was traditionally a disease of childhood, infecting children with a median age of 15 months in 1986.[18] Following the dramatic reduction in Hib meningitis, which primarily occurs among children under age 2 years, the median age of persons with the disease shifted to 25 years in 1995.18 The success of conjugate vaccines against Hib disease has stimulated efforts to develop conjugate vaccines for other pathogens, including Streptococcus pneumoniae, Neisseria meningitidis, and GBS. A conjugate vaccine against S. pneumoniae has been licensed, and vaccines against the other two agents are being tested in clinical trials. The success of bacterial meningitis vaccines suggests comparable results may be achieved for other causes of meningitis, sepsis, and pneumonia as their conjugate vaccines become used more routinely in target populations.

Disparities

The updated Preventing Emerging Infectious Diseases: A Strategy for the 21st Century focuses on certain emerging infectious disease issues and on particular groups of people at risk.[19] Historically, childhood vaccination rates have been lower in certain racial and ethnic populations, compared to the white population. Vaccination rates for preschool children in racial and ethnic groups with lower vaccination rates, however, have been increasing at a more rapid rate, significantly narrowing the gap.

Efforts need to be intensified, particularly to increase vaccination coverage for children living in poverty. Substantial numbers of undervaccinated children remain in some areas, particularly the large urban areas with traditionally underserved populations, creating great concern because of the potential for outbreaks of disease.

In addition to very young children, many adults are at increased risk for VPDs. Vaccination against pneumococcal infections and influenza among persons aged 65 years and older has increased slightly for African Americans and Hispanics. The coverage in these groups, however, remains substantially below the general population. For example, influenza vaccination rates for whites were 66 percent in 1997, while for African Americans and Hispanics, rates were only 45 percent and 53 percent, respectively. In September 1997, the U.S. Department of Health and Human Services approved a plan to improve adult vaccination rates and reduce disparities among racial and ethnic groups.[20] The elimination of disparities, however, may require further interventions in particular geographic, cultural, and racial and ethnic populations.

Opportunities

A coordinated strategy is necessary to understand, detect, control, and prevent infectious diseases. Such a strategy will protect the gains achieved in life expectancy in the 20th century from control and prevention of infectious diseases and ensure further improvements in the 21st century.

Priority issues include antimicrobial resistance, foodborne and waterborne diseases, vector-borne and zoonotic diseases, diseases transmitted through transfusion of blood or blood products, and vaccine development and use. Some of these diseases and pathogens were unknown 20 years ago. Others are reemergent problems once thought under control. At-risk populations include persons with impaired host defenses; pregnant women and newborns; travelers, immigrants, and refugees; older adults; and other persons identified by the Advisory Committee on Immunization Practices (ACIP).

The major strategies to protect people from VPDs are the following:[21]

n	Improving the quality and quantity of vaccination delivery services.

n	Minimizing financial burdens for needy persons.

n	Increasing community participation, education, and partnership.

n	Improving monitoring of disease and vaccination coverage.

n	Developing new or improved vaccines and improving vaccine use.

These strategies include a broad range of interventions for children, such as entry requirements for school and promoting the Vaccines for Children and SCHIP initiatives, in which eligible children are vaccinated in their medical home. Assessment of vaccination coverage of persons served at individual clinics and provider offices with feedback of the results to the individual providers to guide them in improving performance also is important. The exchange of information on coverage assessment among colleagues stimulates a friendly competition to achieve better vaccination levels.[22] Populations at risk of undervaccination can be reached through linkages with other programs, including Women, Infants, and Children (WIC) services.[23] State and local registries that enroll children and record their vaccinations are valuable tools for helping parents and providers to identify immunization needs of individual children, assessing coverage in individual practices, and generating communitywide estimates.[24]

In the United States, most VPDs occur among adults. Pneumococcal disease and influenza account for more than 30,000 deaths annually, most of which occur in elderly persons. Studies have consistently shown that focusing efforts to improve coverage on health care providers, as well as health care systems, is the most effective means of raising vaccine coverage in adults. For example, all health care providers should assess routinely the vaccination status of their patients. Likewise, health plans should develop mechanisms for assessing the vaccination status of their participants. Also, nursing home facilities and hospitals should ensure that policies exist to promote vaccination.

Because no vaccine is completely safe, vaccine safety research and monitoring are necessary to identify and minimize vaccine-related injuries. As programs continue to reduce the new cases of VPDs, concerns about vaccine adverse events have emerged, posing a threat to public acceptance of vaccines. Knowing the safety profile of vaccines is essential to assess accurately the risks and benefits, to formulate appropriate vaccine recommendations, and to address public concerns.

Significant progress has been made in reaching the Healthy People 2000 objectives. Reductions in indigenous cases of VPDs have been dramatic. For example, measles was reduced from a 1988 baseline of 3,396 indigenous cases to a total of only 74 in 1998. Substantial progress also has been made in reducing hepatitis B virus (HBV) transmission. The vaccine against hepatitis A provides the opportunity to reduce the burden of this disease. Achieving the year 2000 objective to reduce new cases of bacterial meningitis was entirely due to the introduction of Hib conjugate vaccines for infants.[25] In 1998, individual coverage levels for children aged 19 to 35 months were at record high levels. For example, individual coverage levels for three or more doses of polio, three or more doses of diphtheria/tetanus/acellular pertussis, one or more doses of measles/mumps/rubella, and three or more doses of Hib vaccines were each at or above 91 percent. Progress also has been made in expanding immunization requirements for schools and day care settings. Data for viral hepatitis indicate that targets for hepatitis B and C were met in the early 1990s.

Note: Unless otherwise noted, data are from the Centers for Disease Control and Prevention, National Center for Health Statistics, Healthy People 2000 Review, 1998–99.

 

Immunization and Infectious Diseases

Goal: Prevent disease, disability, and death from infectious diseases, including vaccine-preventable diseases.

Number	Objective Short Title
Diseases Preventable Through Universal Vaccination
14-1	Vaccine-preventable diseases
14-2	Hepatitis B in infants and young children
14-3	Hepatitis B in adults and high-risk groups
14-4	Bacterial meningitis in young children
14-5	Invasive pneumococcal infections
Diseases Preventable Through Targeted Vaccination
14-6	Hepatitis A
14-7	Meningococcal disease
14-8	Lyme disease
Infectious Diseases and Emerging Antimicrobial Resistance
14-9	Hepatitis C
14-10	Identification of persons with chronic hepatitis C
14-11	Tuberculosis
14-12	Curative therapy for tuberculosis
14-13	Treatment for high-risk persons with latent tuberculosis infection
14-14	Timely laboratory confirmation of tuberculosis cases
14-15	Prevention services for international travelers
14-16	Invasive early onset group B streptococcal disease
14-17	Peptic ulcer hospitalizations
14-18	Antibiotics prescribed for ear infections
14-19	Antibiotics prescribed for common cold
14-20	Hospital-acquired infections
14-21	Antimicrobial use in intensive care units
Vaccination Coverage and Strategies
14-22	Universally recommended vaccination of children aged 19 to 35 months
14-23	Vaccination coverage for children in day care, kindergarten, and first grade
14-24	Fully immunized young children and adolescents
14-25	Providers who measure childhood vaccination coverage levels
14-26	Children participating in population-based immunization registries
14-27	Vaccination coverage among adolescents
14-28	Hepatitis B vaccination among high-risk groups
14-29	Influenza and pneumococcal vaccination of high-risk adults
Vaccine Safety
14-30	Adverse events from vaccinations
14-31	Active surveillance for vaccine safety

 

Diseases Preventable Through Universal Vaccination

14-1.		Reduce or eliminate indigenous cases of vaccine-preventable diseases.

Target and baseline:

Objective	Reduction in Vaccine-Preventable Diseases	1998 Baseline	2010 Target
		Number of Cases
14-1a.	Congenital rubella syndrome (children under age 1 year)	7	0
14-1b.	Diphtheria (persons under age 35 years)	1	0
14-1c.	Haemophilus influenzae type b* (children under age 5 years)	163	0
14-1d.	Hepatitis B (persons aged 2 to 18 years)	945†	9
14-1e.	Measles (persons of all ages)	74	0
14-1f.	Mumps (persons of all ages)	666	0
14-1g.	Pertussis (children under age 7 years)	3,417	2,000
14-1h.	Polio (wild-type virus) (persons of all ages)	0	0
14-1i.	Rubella (persons of all ages)	364	0
14-1j.	Tetanus (persons under age 35 years)	14	0
14-1k.	Varicella (chicken pox) (persons under age 18 years)	4 million‡	400,000

*Includes cases with type b and unknown serotype.
†Estimated hepatitis B cases for 1997.[26]
‡Data based on average from 1990–94 for persons of all ages.

Target setting method: Total elimination for congenital rubella syndrome, diphtheria, Haemophilus influenzae type b, measles, mumps, polio, rubella, and tetanus; 41 percent improvement for pertussis; 99 percent improvement for hepatitis B; and 99 percent improvement for varicella.

Data sources: National Notifiable Disease Surveillance System (NNDSS), CDC, EPO; National Congenital Rubella Syndrome Registry (NCRSR), CDC, NIP—congenital rubella syndrome; Active Bacterial Core Surveillance (ABCs), Emerging Infections Programs, CDC, NCID—Haemophilus influenzae type b; National Health Interview Survey (NHIS), CDC, NCHS—varicella.

Highly effective vaccines are used routinely in childhood for prevention of measles, mumps, rubella, varicella, diphtheria, tetanus, pertussis, polio, hepatitis B, and invasive Hib disease.[27] Vaccinations for these diseases have reduced reported cases of most VPDs common in childhood to record-low levels.11, 26,[28] Measles transmission probably was interrupted multiple times in the United States since 1993.[29], [30], [31] With a high level of coverage of two doses of measles, mumps, and rubella vaccine, interruption of the spread of both rubella and mumps is feasible.[32], [33] Recent outbreaks of rubella and a number of cases of congenital rubella syndrome, however, highlight the importance of ensuring rubella immunity, particularly in women of child-bearing age and foreign-born adults.[34] Polio has been eliminated in the United States due to high vaccination coverage. Although polio is expected to be eradicated globally, surveillance for cases of the disease will continue. Because of widespread vaccination, reported cases of diphtheria are near zero.[35], [36] Tetanus toxoid is highly effective, but with the absence of group immunity, all persons must be vaccinated to achieve the goal of zero cases.[37] Pertussis among children will be reduced by increasing vaccination coverage, but the disease will continue to occur because the organism circulates among older age groups, and the vaccine is not 100 percent effective.[38], [39]

Hepatitis B virus (HBV) infection will be reduced greatly as the age groups covered by universal infant and adolescent vaccination efforts enter young adulthood, a periodwhen the risk of HBV infection increases.

Conjugate vaccines for prevention of Hib are highly effective and have led to near elimination of invasive Hib disease.17, [40] Further reductions in new cases are anticipated as Hib vaccine coverage increases.

The licensure of new vaccines against common diseases that are not reportable diseases, such as varicella, has created new challenges for surveillance and evaluation. Without national reporting, documenting the impact of national and State vaccination programs and measuring progress for reducing indigenous cases of disease are difficult.[41] However, with an increase in vaccination coverage and a decline in the number of new cases, varicella is expected to become a reportable condition.

14-2		Reduce chronic hepatitis B virus infections in infants and young children (perinatal infections).

Target: 400 infections.

Baseline: 1,682 chronic hepatitis B virus infections in children under age 2 years were reported in 1995.

Target setting method: 76 percent improvement.

Data sources: Perinatal Hepatitis B Prevention Program, CDC, NCID; National Vital Statistics System (NVSS), CDC, NCHS; State Perinatal Hepatitis B Prevention Programs; State Vital Statistics Systems.

Each year, 16,000 to 18,000 children in the United States are born to mothers infected with HBV.[42] Without prevention programs, about 8,000 of these infants would become infected with HBV. Ninety-five percent of the infections, however, are preventable through appropriate maternal screening and infant care.[43]

Screening pregnant women during an early prenatal visit is essential to identify those who are infected. Women at high risk should be retested late in pregnancy. In 1997, 14 States had laws or regulations to ensure such screening.

To be maximally effective, steps to prevent transmission of HBV to infants born to mothers who are infected must begin as soon as the child is born. Such infants should receive a first dose of hepatitis B vaccine within 12 hours of birth, along with hepatitis B immune globulin (HBIG), and two more doses of vaccine by age 6 months. Children need to be tested between the ages of 12 and 15 months to ensure that they are not infected and have developed immunity to the virus.

14-3.		Reduce hepatitis B.

Target and baseline:

Objective	Reduction in Hepatitis B	1997 Baseline	2010 Target
	Adults	Rate per 100,000 Population
14-3a.	19 to 24 years	24.0	2.4
14-3b.	25 to 39 years	20.2	5.1
14-3c.	40 years and older	15.0	3.8
	High-risk groups	Number of Cases
14-3d.	Injection drug users	7,232	1,808
14-3e.	Heterosexually active persons	15,225	1,240
14-3f.	Men who have sex with men	7,232	1,808
14-3g.	Occupationally exposed workers	249	62

Target setting method: Better than the best for 14-3a, 14-3b, and 14-3c; 75 percent improvement for 14-3d, 14-3f, and 14-3g; 92 percent improvement for 14-3e.

Data sources: National Notifiable Disease Surveillance System (NNDSS), CDC, EPO; Sentinel Counties Study of Viral Hepatitis, CDC, NCID.

Select Age Groups, 1997	Hepatitis B Cases
	14-3a. Aged 19 to 24 Years		14-3b. Aged 25 to 39 Years	14-3c. Aged 40 Years and Older
	Rate per 100,000
TOTAL	24.0	20.2		15.0
Race and ethnicity
American Indian or Alaska Native	16.0	20.1		10.9
Asian or Pacific Islander	42.2	30.4		33.2
Asian	DNC	DNC		DNC
Native Hawaiian and other Pacific Islander	DNC	DNC		DNC
Black or African American	48.3	32.5		27.6
White	10.4	10.2		7.4
Hispanic or Latino	16.9	16.0		18.1
Not Hispanic or Latino	25.2	20.7		14.8
Black or African American	50.6	34.1		28.4
White	10.3	10.2		7.1
Gender
Female	24.1	15.4		9.4
Male	22.5	24.1		20.8
Family income level
Poor	DNC	DNC		DNC
Near poor	DNC	DNC		DNC
Middle/high income	DNC	DNC		DNC

DNA = Data have not been analyzed. DNC = Data are not collected. DSU = Data are statistically unreliable.

To reduce HBV transmission in the United States by 2010, vaccination programs must be targeted to adolescents and adults in high-risk groups. The primary means of achieving high levels of vaccination coverage in groups with behavioral risk factors for HBV infection is to identify settings where these individuals can be vaccinated. Such sites include clinics that treat sexually transmitted diseases (STDs), correctional facilities (juvenile detention facilities, prisons, jails), drug treatment clinics, and community-based HIV prevention sites. The primary means of achieving high levels of vaccine coverage among household and sex contacts of the estimated 1.25 million persons in the United States with chronic HBV infection are programs that offer followup for all hepatitis B surface antigen (HBsAg)-positive persons reported to State and local health departments.

Routine infant vaccination eventually will produce a highly immune population sufficient to eliminate HBV transmission in the United States. However, high rates of acute hepatitis B continue to occur, with an estimated 65,000 cases in 1996. Most cases occur in young adult risk groups, including persons with a history of multiple sex partners, men who have sex with men, injection drug users, incarcerated persons, and household and sex contacts of persons with HBV infection. Investigation of reported cases of acute hepatitis B indicates that as many as 70 percent of these individuals previously had been seen in settings, such as drug treatment clinics, correctional facilities, or clinics for the treatment of STD, where they could have received vaccine.

14-4.		Reduce bacterial meningitis in young children.

Target: 8.6 new cases per 100,000 children aged 1 through 23 months.

Baseline: 13.0 new cases of bacterial meningitis per 100,000 children aged 1 through 23 months were reported in 1998.

Target setting method: 34 percent improvement. (Better than the best will be used when data are available.)

Data source: Active Bacterial Core Surveillance (ABCs), CDC, NCID.

Children Aged 1 Through 23 Months, 1998	New Cases of Bacterial Meningitis
	Rate per 100,000
TOTAL	13.0
Race and ethnicity
American Indian or Alaska Native	DSU
Asian or Pacific Islander	DSU
Asian	DNC
Native Hawaiian and other Pacific Islander	DNC
Black or African American	25.9
White	11.0
Hispanic or Latino	DSU
Not Hispanic or Latino	DSU
Black or African American	DSU
White	DSU
Gender
Female	13.0
Male	13.1
Family income level
Poor	DNC
Near poor	DNC
Middle/high income	DNC