21st February 2024

Types of vaccines

Overview

It is important to be aware of the common types of vaccines along with specific situations where certain vaccines should not be given. 

Vaccines stimulate the immune system to recognise pathogens and produce antibodies against the pathogen. There are several types of vaccines used in current clinical practice:

• Live attenuated vaccine – Weakened ( attenuated) whole bacteria/virus by modifying the pathogen’s genetic material. This appears to elicit the best immune response but may result in uncontrolled pathogen replication in patients with weakened immune systems. Examples include:
  • Rotavirus 
  • Varicella/shingles
  • BCG
  • Yellow fever
  • ORAL typhoid
  • Live influenza
  • MMR
• Inactivated vaccine – Whole pathogens that have been killed or modified so that they are incapable of replicating. Examples include:
  • Inactivated polio
  • Hepatitis A
  • Rabies 
  • Japanese encephalitis
  • Inactivated influenzae 
• Recombinant protein vaccine – Protein subunits are created by inserting pathogenic DNA into yeast cells to produce polysaccharides/proteins that induce an immune response. Examples include:
  • Hepatitis B
  • Human papilloma virus
  • Meningococcal B
• Toxoid vaccine – Inactivated toxins are produced to induce immunity without causing clinical symptoms due to the inactivated nature of the toxoid. Examples include:
  • Diphtheria
  • Tetanus
  • Pertussis
• Conjugate vaccine – The pathogen’s polysaccharide antigen is attached to another material to induce a more robust immune response against the polysaccharide antigen. Examples include: 
  • Haemophilus influenzae B 
  • Meningococcal A,C,W,Y
  • Pneumococcal

Special considerations

Vaccines have very few absolute contraindications and have few side effects. The most common absolute contraindication to vaccines includes:

• Confirmed anaphylactic reaction to previous vaccine dose
• Confirmed anaphylactic reaction to a component within the vaccine

Special considerations should be undertaken with the following patient populations:

• Egg/Latex allergy
• Primary/acquired immunodeficiency
  • This includes acute/chronic lymphoma and leukaemia; HIV/AIDS; cellular immunodeficiency due to SCID; Wiskott-Aldrich syndrome; DiGeorge syndrome; and recent stem cell transplant within the past 24 months. 
• Immunosuppressive therapies, including biological therapies
  • This includes chemotherapy, radiotherapy, high-dose corticosteroids, immunosuppression for solid organ transplants, and higher doses of methotrexate and azathioprine.
  • Low-dose corticosteroids and lower doses of non-biologic immune-modulating medications are not sufficient immunosuppression to withhold live vaccines. 
• Pregnancy

Patients with the above special consideration should not receive live, attenuated vaccines. Before administration, the relevant speciality prescribing the immunosuppressive therapy should be consulted. In pregnancy, live vaccinations should not be given due to the theoretical risk of foetal infection. Other vaccine types are safe to be administered to all these patient groups. 

References

• Vaccine Knowledge Project. (2021). Types of Vaccine. Accessed on 2022 Mar 28. Available from: https://vk.ovg.ox.ac.uk/vk/types-of-vaccine.
• UK Health Security Agency, & Department of Health & Social Care. (2020). Contraindications and special consideration. Accessed on 2022 Mar 28. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/655225/Greenbook_chapter_6.pdf. 
• UK Health Security Agency, & Department of Health & Social Care. (2020). Immunity and how vaccines work. Accessed on 2022 Mar 28. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/949797/Greenbook_chapter_1_Jan21.pdf.