Challenges in Adult Vaccination Eduardo de Gomensoro, Giuseppe Del Giudice, and T. Mark Doherty. Annals of Medicine.January 16, 2018 Powerpoint by Wilmark Gular, MD

Introduction

Jenner’s inoculation of the smallpox virus started an era of eradicating infections.1 There are over twenty vaccines used today to help prevent specific infections.   Children are prone to contract infections due to their immature immunity. Most vaccines are geared toward protecting the young from preventable illnesses. The older adult are also at risk for diseases such as pneumonia and herpes zoster. Immunosenescence2, the age-related deterioration of the immune system, predisposes the older adult to infections.

  Most developed countries have programs for immunizing the adult but there is a lower coverage compared to children. The Centers for Disease Control recommends a schedule for adult vaccination aged 19 years and above.3 This technical article identifies the different factors associated with problems in adult vaccination.

Relevance

The concept of healthy aging includes a healthy triad4 consisting of a healthy diet, exercise, and vaccination. Vaccination in the adult is low due to lack of education and the costs involved in availing such service. Immunosenescence contributes to failure of some vaccines. Life-course immunization approach and new vaccine technologies may help increase the coverage and success rate of vaccines in adults.

Objectives

The article identifies the following factors associated with vaccine failure : physiologic, demographic, technical, economic , political The article also addresses strategies to make adult immunization effective and sustainable.

Highlights

The Aging Population Adults aged 60 years and up is expected to rise to 22 to 25 % of the total global population in 2050.5   This rise of the adult population would result to an increase in the prevalence of non-communicable as well as infectious diseases. Measures in addressing this issue, specifically primary preventive strategies such as vaccination, can be planned and implemented.

Noncommunicable and Infectious Diseases in Adults Noncommunicable diseases still remain the top diseases among adults in a global scale. These have been reduced by nutrition, exercise, and medical care. With the control of these diseases, adult lifespan is expected to be longer. There has only been modest reductions in cases of influenza and pneumonia in adults despite the availability of vaccines. Infectious diseases contribute to a significant percentage of morbidity and mortality in the said population.

Immunosenescence and Age Related Immune Responsiveness Immunosenescence results from greater differentiation of immune cells into myeloid progenitors compared to lymphoid ones. This results to lower antibody production and is illustrated by the lower success rate of vaccination against herpes zoster for ages 70 and up. The timing of vaccination also contributes to effective vaccination. This is demonstrated by a higher success rate of the combination of Hepatitis A and B vaccine compared to its monovalent counterparts among adults.

Lower Vaccination Coverage among Adults Reduced awareness on the benefits and schedule of vaccines and the costs of the vaccine contribute to lower vaccine coverage As such, the burden of vaccine-preventable infections remain high.

Lower Vaccination Coverage among Adults

Advances in Vaccine Technology The adjuvanted trivalent influenza vaccine has shown higher immune response among adults compared to the unadjuvanted vaccine. A herpes zoster subunit vaccine also has undergone adjuvantation with a liposomal based formulation and has been shown to have higher efficacy.

Effective Vaccination Strategy Public awareness on the importance of vaccination must be increased. Healthcare workers must take bold steps in promoting vaccination. The vaccination schedule must be arranged to fit in with the patient’s schedule. The national government must ensure that a program is available and running.   Vaccination remains to be a cost-effective strategy in reducing morbidity and mortality from infectious diseases. Life-course immunization costs are lesser than other primary prevention strategies.

Conclusion

There are a myriad of challenges hounding adult vaccination. From immunosenescence to problems in promoting adult vaccination, the list of problems seem to be unending. There is hope in developing and implementing strategies such as the life-course immunization program to increase overall adherence to vaccination.

References Boylston A. The Origins of Vaccination: Myths and Realities. Journal of the Royal Society of Medicine. 2013. Aw, D. et al. Immunosenescence: Emerging Challenges for an Ageing Population. Immunology. 2007. Centers for Disease Control and Prevention.Recommended Immunization Schedule for Adults Aged 19 Years or Older, United States.2018. Gomensoroet. al. Challenges in Adult Vaccination. Annals of Medicine. 2018