ADULT IMMUNISATION

Adult Immunization


Immunization in adults is a crucial component of public health strategy aimed at preventing morbidity and mortality from infectious diseases. It helps in extending protection from childhood vaccinations, addressing gaps in immunity, and providing new vaccinations to those at risk due to age, occupational hazards, lifestyle, or underlying health conditions.

Importance of Adult Immunization

  1. Prevents Disease: Protects against diseases that are more common or serious in adults, such as influenza, pneumococcal disease, and shingles.
  2. Reduces Disease Spread: Helps in controlling the spread of infections to vulnerable populations including infants, the elderly, and immunocompromised individuals.
  3. Cost-effective: Reduces healthcare costs by minimizing the burden of treatable diseases and their complications.

Recommended Vaccines for Adults

The following table outlines the vaccines recommended for adults based on their age group and health conditions:

Vaccine Indicated Population Recommended Age/Situation Booster Needed?
Influenza All adults Annually No
Tetanus, Diphtheria, Pertussis (Tdap) All adults Every 10 years, Tdap once then Td or Tdap Yes, every 10 years
Zoster (Shingles) Adults 50 years and older Two doses of RZV or one dose of ZVL No
Pneumococcal Adults 65 years and older One dose PCV13, followed by PPSV23 Yes, specific intervals
Human Papillomavirus (HPV) Adults up to age 26 3 doses No
Hepatitis A and B At-risk populations 2 or 3 doses depending on the vaccine type No
Meningococcal At-risk populations & all adults Once with booster in high-risk individuals Yes, for at-risk groups
COVID-19 All adults Primary series and boosters as recommended As per guidelines

1. Influenza Vaccine

  • Indications: Annual vaccination against influenza is recommended for all adults to prevent the flu virus and its severe complications.
  • Mechanism: The vaccine stimulates the immune system to produce antibodies against the influenza virus, typically targeting three to four strains predicted to be prevalent in the upcoming flu season.
  • Dosing: One dose annually. Different formulations are available:
    • Standard dose flu shots for all adults.
    • High-dose or adjuvanted flu shots specifically for adults 65 years and older.
    • Nasal spray vaccine (live attenuated influenza vaccine) is an option for non-pregnant adults aged 18-49 years.
  • Side Effects: Common side effects include soreness at the injection site, headache, fever, nausea, and muscle aches.

2. Tetanus, Diphtheria, Pertussis (Tdap)

  • Indications: Protection against tetanus, diphtheria, and pertussis, all of which can lead to severe respiratory complications and even death.
  • Mechanism: The vaccine components act by inducing antibodies that neutralize the toxins released by the bacteria causing these diseases.
  • Dosing: One dose of Tdap is recommended for all adults who have not previously received it, followed by a Td (tetanus and diphtheria) booster every 10 years.
  • Side Effects: Pain at the injection site, mild fever, headache, fatigue, and in rare cases, more severe reactions like allergic responses.

3. Zoster (Shingles) Vaccine

  • Indications: Recommended for the prevention of herpes zoster (shingles) and its complications in individuals aged 50 years and older.
  • Mechanism: The recombinant zoster vaccine (RZV) stimulates the body’s immune system to recognize and combat the varicella-zoster virus, which remains dormant in those who have had chickenpox.
  • Dosing:
    • RZV (Shingrix): Administered in two doses, 2 to 6 months apart.
  • Side Effects: Pain and swelling at the injection site, muscle pain, headache, shivering, fever, and stomach upset.

4. Pneumococcal Vaccine

  • Indications: Prevents pneumococcal diseases such as pneumonia, meningitis, and sepsis, particularly in adults over 65 years or those with chronic health conditions.
  • Mechanism: Vaccines like PCV13 and PPSV23 introduce parts of the pneumococcal bacteria to the immune system to develop specific antibodies.
  • Dosing:
    • PCV13: A one-time dose for adults aged 65+ or younger adults with specific health conditions.
    • PPSV23: One or two doses recommended for the same demographics, depending on their risk factors, with a five-year gap between doses if a second dose is required.
  • Side Effects: Local reactions at the injection site, fever, muscle pain, and fatigue.

5. Human Papillomavirus (HPV) Vaccine

  • Indications: Protects against cancers caused by HPV infections, including cervical, anal, and oropharyngeal cancers.
  • Mechanism: The vaccine prevents infection with the most cancer-associated HPV types by inducing antibodies that neutralize the virus.
  • Dosing: A series of 2-3 injections over six months, depending on the age at the initial vaccination.
  • Side Effects: Most commonly, pain at the injection site, swelling, redness, and sometimes headaches or fever.

6. Hepatitis A and B Vaccines

  • Indications: Prevent infection from Hepatitis A and B viruses, which cause liver inflammation and can lead to chronic liver disease.
  • Mechanism: These vaccines generate an immune response that produces antibodies against the hepatitis viruses, preventing their proliferation.
  • Dosing:
    • Hepatitis A: Typically two doses, six months apart.
    • Hepatitis B: Three doses, with the second dose given one month after the first and the third dose six months after the first.
  • Side Effects: Sore arm, headache, and low-grade fever are common.

7. Meningococcal Vaccine

  • Indications: Prevents meningitis and other infections caused by meningococcal bacteria. Recommended for people in communal living settings, certain medical conditions, or traveling to countries where meningitis is common.
  • Mechanism: The vaccine works by introducing components of the Neisseria meningitidis bacteria to the immune system, inducing an immune response.
  • Dosing:
    • MenACWY (conjugate vaccine): First dose in teenagers, with a booster at age 16. Adults in high-risk groups may need additional doses.
    • MenB (serogroup B meningococcal vaccine): May be recommended for young adults and individuals at increased risk of serogroup B meningococcal disease.
  • Side Effects: Pain at the injection site, sometimes a fever or fatigue.

8. COVID-19 Vaccine

  • Indications: Recommended for all adults to prevent COVID-19 and potentially severe complications associated with the virus.
  • Mechanism: mRNA vaccines (e.g., Pfizer and Moderna) introduce a piece of genetic material that instructs cells to produce a protein similar to the spike protein of SARS-CoV-2, eliciting an immune response.
  • Dosing: Varies depending on the vaccine manufacturer. Boosters are recommended to maintain immunity against emerging variants.
  • Side Effects: Pain at the injection site, fever, chills, fatigue, and headache. Side effects generally last a few days.

Bibliography

  1. Centers for Disease Control and Prevention (CDC). (2022). Adult Immunization Schedule. Available at: https://www.cdc.gov/vaccines/schedules/hcp/adult.html
  2. World Health Organization (WHO). (2022). Vaccines and Immunization. Available at: https://www.who.int/health-topics/vaccines-and-immunization#tab=tab_1
  3. Hamborsky, J., Kroger, A., & Wolfe, S. (Eds.). (2015). Epidemiology and Prevention of Vaccine-Preventable Diseases (13th ed.). Public Health Foundation. Available at: https://www.cdc.gov/vaccines/pubs/pinkbook/index.html
  4. Plotkin, S. A., Orenstein, W. A., & Offit, P. A. (2018). Plotkin’s Vaccines (7th ed.). Elsevier.
  5. Schillie, S., Vellozzi, C., Reingold, A., Harris, A., Haber, P., Ward, J. W., & Nelson, N. P. (2018). Prevention of Hepatitis B Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices. MMWR Recommendations and Reports, 67(1), 1-31. DOI: 10.15585/mmwr.rr6701a1
  6. Kim, D. K., Hunter, P., & Swamy, G. K. (2020). Recommended Adult Immunization Schedule, United States, 2020. Annals of Internal Medicine, 172(5), 337-347. DOI: 10.7326/M19-3700
  7. Shingrix vaccine information. (2022). GSK Source. Available at: https://www.gsksource.com/shingrix
  8. Harper, D. M., DeMars, L. R. (2017). HPV Vaccines – A Review of the First Decade. Gynecologic Oncology, 146(1), 196-204. DOI: 10.1016/j.ygyno.2017.04.004
  9. COVID-19 Vaccine information. (2022). U.S. Food and Drug Administration (FDA). Available at: https://www.fda.gov/vaccines-blood-biologics/covid-19-vaccines
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