Adult immunization

Abstract

Vaccination is recommended throughout life to prevent vaccine-preventable diseases and their sequel. The primary focus of vaccination programs has historically been directed to childhood immunizations. For adults, chronic diseases have been the primary focus of preventive and medical health care, though there has been increased emphasis on preventing infectious diseases. Adult vaccination coverage, however, remains low for most of the routinely recommended vaccines. Though adults are less susceptible to fall prey to traditional infectious agents, the probability of exposure to infectious agents has increased manifold owing to globalization and increasing travel opportunities both within and across the countries. Thus, there is an urgent need to address the problem of adult immunization. The adult immunization enterprise is more complex, encompassing a wide variety of vaccines and a very diverse target population. There is no coordinated public health infrastructure to support an adult immunization program as there is for children. Moreover, there is little coordination among adult healthcare providers in terms of vaccine provision. Substantial improvement in adult vaccination is needed to reduce the health consequences of vaccine-preventable diseases among adults. Routine assessment of adult patient vaccination needs, recommendation, and offer of needed vaccines for adults should be incorporated into routine clinical care of adults.

Introduction

Immunization is one of the most effective public health interventions, reducing or eliminating the burden of many infectious diseases.¹ The primary focus of vaccination programs has historically been directed to childhood immunizations. For adults, chronic diseases have been the primary focus of preventive and medical health care, though there has been increased emphasis on preventing infectious diseases. Adult vaccination coverage, however, remains low for most of the routinely recommended vaccines.² Protecting adults through vaccination has never been considered a preventive strategy likely to have a great impact on population health. Though adults are less susceptible to fall prey to traditional infectious agents, emergence of HIV/AIDS, and re-emergence of malaria and tuberculosis world over has complicated the prevailing fragile health scenario. Also, the probability of exposure to infectious agents have increased manifold owing to globalization and increasing travel opportunities both within and across the countries. Despite the availability of vaccines, many adults remain unvaccinated because they are unaware of the need for adult vaccines or are misinformed about vaccines and the diseases they are designed to prevent. Thus, there is an urgent need to address the problem of adult immunization.

Burden of Vaccine Preventable Diseases

According to world health statistics 2013, in a year, there were 4880 reported cases of diphtheria, 162 047 reported cases of pertussis, 14 272 reported cases of tetanus, 354 820 reported cases of measles, 726 169 reported cases of mumps, and 114 449 reported cases of rubella.³ Globally, in 2011, there were 2500 deaths due to diphtheria,⁴158 000 measles deaths—about 430 deaths every day or 18 deaths every hour.⁵ Worldwide, annual epidemics of influenza result in about three to five million cases of severe illness, and about 250 000 to 500 000 deaths.⁶ Among healthy adults, influenza vaccine can prevent 70% to 90% of influenza-specific illness. Among the elderly, the vaccine reduces severe illnesses and complications by up to 60% and deaths by 80%. The Hepatitis A virus has a worldwide distribution and causes about 1.4 million cases of clinical hepatitis each year.⁷ More than 240 million people have chronic (long-term) liver infections. About 600 000 people die every year due to the acute or chronic consequences of hepatitis B. Hepatitis B prevalence is highest in sub-Saharan Africa and East Asia. Most people in these regions become infected with the hepatitis B virus during childhood and between 5–10% of the adult population are chronically infected.⁸ HPV is estimated to cause 100% of cervical cancer cases, 90% of anal cancer cases, 40% of cases of cancers of the external genitalia (vulva, vagina, and penis), at least 12% of oro-pharyngeal cancer cases, and at least 3% of oral cancer cases.⁹ Cervical cancer is the second most common cancer in women, with an estimated 530 000 new cases every year. Every year, more than 270 000 women die from cervical cancer; more than 85% of these deaths are in low- and middle-income countries.¹⁰

Barriers and Challenges of Adult Immunization

The common barrier to immunization in adulthood include¹¹

• Lack of recognition of the importance of adult immunization,

• Lack of recommendation from health care providers,

• Lack of health care provider knowledge about adult immunization and recommended vaccines,

• Misrepresentation/misunderstanding of the risks of vaccine and benefits of disease prevention in adults,

• Lack of understanding of vaccine safety and efficacy,

• Missed opportunities for vaccination in health care providers' offices, hospitals, and nursing homes,

• Lack of publicly-funded vaccine and reimbursement to vaccine providers,

• Lack of coordinated immunization programs for adults,

• Lack of regulatory or legal requirements,

• Fear of injections, and

• Lack of availability of up-to-date records and recording systems.

Adult immunization is an emerging issue that has seen an increasing emphasis in clinical care and health professional training programs.

The organization of the childhood and adult immunization enterprises are very different. The childhood immunization program involves a universal schedule encompassing a limited age range and involves a relatively narrow network of provider types. The adult immunization enterprise is more complex, encompassing a wide variety of vaccines and a very diverse target population ranging from healthy young adults to young adults and elderly with chronic conditions to those who are less likely to have a medical home and seek medical care in non-traditional settings. This diverse patient population is in turn served by an equally diverse network of health care providers. Additionally, vaccination recommendations for adults span the interface between adolescents and adults (human papillomavirus and meningococcal vaccines), include vaccines that are universally recommended (influenza) as well as those that are recommended for certain age groups (herpes zoster), vaccines targeted to individuals with specific risk factors (hepatitis A and B), travel vaccines (e.g., typhoid, yellow fever, polio), and vaccines targeted to particular combinations of age and risk factors (pneumococcal).

There is no coordinated public health infrastructure to support an adult immunization program as there is for children and little coordination among adult healthcare providers in terms of vaccine provision.¹² This lack of coordination was highlighted as a barrier to effective delivery of H1N1 influenza vaccine during the 2009–10 H1N1 influenza vaccination program¹³ and remains a barrier to other routine adult immunizations.¹⁴

Recommended Adult (aged 19 y and older) Immunization Schedule

Table 1 shows CDC recommended adult (aged 19 y and older) immunization schedule, by vaccine and age group and Table 2 shows recommended vaccinations indicated for adults based on medical and other indications.¹⁵ However, it needs to be appreciated that there may be variation from country to country and each vaccine has its own specific considerations which may need to be addressed individually.

Table 1. Recommended adult (aged 19 y and older) immunization schedule, by vaccines and age group.

Vaccines	19–21 y	22–26 y	27–49 y	50–59 y		60–64 y	>65 y
Influenza	1 dose annually
Td/Tdap	Substitute 1-time dose of Tdap for Td booster, then boost with Td every 10 y
Varicella	2 doses
HPV (Female)	3 doses through age 26 y		Not Recommended
HPV (Male)	3 doses through age 21 y or may be through 26 y*		Not Recommended
Zoster	Not Recommended					1 dose
MMR	1 or 2 doses				Not Recommended
PPSV23	1 or 2 doses*						1 dose
PCV13	1 dose*
Meningococcal	1 or more dose*
Hepatitis A	2 doses*
Hepatitis B	3 doses*

Td/Tdap, tetanus, diphtheria, pertussis; HPV, human papilloma virus; MMR, measles, mumps, rubella; PPSV23, pneumococcal polysaccharide vaccine; PCV13, pneumococcal 13-valent conjugate vaccine. *Vaccine is recommended for adults with certain risks related to their health, job or lifestyle that put them at higher risk for serious diseases.

Table 2. Recommended vaccinations indicated for adults based on medical and other indications.

Vaccines	Pregnancy	Immuno Compromising conditions (excluding HIV)	HIV infection CD4+ T lymphocyte count		MSM	Heart Disease, Chronic lung disease, chronic alcoholism	Asplenia (including elective splenectomy, persistent complement component deficiency)	Chronic liver disease	Kidney failure, end stage renal disease, receipt of hemodialysis	Diabetes	Health care personnel
			<200 cells/µl	≥200 cells/µl
Influenza	1 dose IIV annually				1 dose IIV or LAIV annually	1 dose IIV annually	1 dose IIV annually				1 dose IIV or LAIV annually
Td/Tdap	1 dose Tdap each pregnancy	Substitute 1-time dose of Tdap for Td booster; then boost with Td every 10 y					Substitute 1-time dose of Tdap for Td booster; then boost with Td every 10 y
Varicella	Contraindicated			2 doses			2 doses
HPV (Female)	NR	3 doses through 26 y			NR	3 doses through 26 y	3 doses through 26 y
HPV (Male)	NR	3 doses through 26 y				3 doses through 21 y	3 doses through 21 y
Zoster	Contraindicated			NR	1 dose		1 dose
MMR	Contraindicated			1 or 2 dose			1 or 2 doses
PPSV23	1 or 2 doses*	1 or 2 doses			1 or 2 doses*	1 or 2 doses	1 or 2 doses				1 or 2 doses*
PCV13	NR	1 dose			1 dose*	1 dose*	1 dose	1 dose*	1 dose	1 dose*	1 dose*
Meningococcal	1 or more doses*						1 or more dose	1 or more dose*	1 or more dose*	1 or more dose*	1 or more dose*
Hepatitis A	2 doses*				2 doses	2 doses*	2 doses*	2 doses	2 doses*	2 doses*	2 doses*
Hepatitis B	3 doses*		3 doses			3 doses*	3 doses*	3 doses

NR, not recommended; MSM, men who have sex with men; IIV, inactivated influenza vaccine; LAIV, live attenuated influenza vaccine. *Vaccine is recommended for adults with certain risks related to their health, job or lifestyle that put them at higher risk for serious diseases.

Conclusion

Substantial improvement in adult vaccination is needed to reduce the health consequences of vaccine-preventable diseases among adults. Health-care provider recommendations for vaccination are associated with increased uptake of patient vaccination.^16-18 It is the responsibility of health care providers to routinely assess the adult patient vaccination needs, recommendation, and offer of needed vaccines for adults. Successful vaccination programs combine:

• education of potential vaccine recipients and publicity to promote vaccination;

• increased access to vaccination services in medical and complementary settings, such as workplaces and commercial establishments (e.g., pharmacies); and

• use of practices shown to improve vaccination coverage, including reminder-recall systems, efforts to remove administrative and financial barriers to vaccination, use of standing order programs for vaccination, and assessment of practice-level vaccination rates with feedback to staff members.¹⁹

In addition to increasing routine vaccination delivery to adults, development of a comprehensive and sustainable adult immunization program will improve public health preparedness and emergency response capability (e.g., delivery of medical counter measures, dissemination of information).

10.4161/hv.26797