Vaccines

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton  

Introduction

Vaccination is one of the most effective ways to prevent diseases. Vaccines protect against more than 25 debilitating or life-threatening diseases, including measles, polio, diphtheria, meningitis, influenza, tetanus, typhoid and cervical cancer.[1]

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A vaccine is a pharmacologic compound that improves a person's immunity to a particular disease.

  • When a disease-causing bacterium or virus invades the human body, the immune system recognizes the material as foreign, usually by detecting specific protein portions of the invading organism, known as antigens.
  • Vaccines contain a form of the disease-causing agent, whether it be a weakened or killed form of the microbe itself, an inactivated version of its toxins, or a protein from the surface of the microbe.
  • By introducing a form of the agent, the vaccine presents the antigen to the immune system, allowing it to recognize the antigen as foreign and develop antibodies and memory T-lymphocytes against those antigens.
  • This allows a more rapid and robust immune response should the body be exposed to the organism in the future.
  • In the absence of vaccination, the first exposure to the natural organism may prove fatal before the immune system can mount a sufficient immune response.[2]

Currently, the majority of children receive their vaccines on time. However, nearly 20 million worldwide still miss out – putting them at risk of serious diseases, death, disability and ill health.[1]

Vaccines are a form of immunotherapy.

Developing A New Vaccine

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Image R: Vaccine candidate mechanisms for SARS-CoV-2 The general stages of the development cycle of a vaccine are:

  • Exploratory stage
  • Pre-clinical stage
  • Clinical development - 3 phase process. During Phase I, small groups of people receive the trial vaccine. In Phase II, the clinical study is expanded and vaccine is given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In Phase III, the vaccine is given to thousands of people and tested for efficacy and safety.
  • Regulatory review and approval
  • Manufacturing
  • Quality control[3]

The 4.5 minute video below is an interesting watch

[4]

A vaccine would be the ultimate weapon against the coronavirus and the best route back to normal life. Trumps administrative coronavirus task force estimate a vaccine could arrive in at least 12 to 18 months.

The grim truth behind this rosy forecast is that a vaccine probably won’t arrive any time soon.

  • Clinical trials almost never succeed.
  • We’ve never released a coronavirus vaccine for humans before.
  • Our record for developing an entirely new vaccine is at least four years — more time than the public or the economy can tolerate social-distancing orders[5][6]

Clinical Significance

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Vaccination is vital to public health. Disease prevention has been proven to prolong life expectancy and improve quality of life.

  • Antivaccination movements have gained traction - diseases once thought to be eradicated or nearly eradicated have had significant outbreaks.
  • Preventive measures such as vaccines are often overlooked by primary care providers and patients. For children, parents often do not know the appropriate schedule for vaccines, and therefore are often unaware of when their children are behind on vaccinations. Another common reason for missed vaccination is missed appointments for various reasons. Patient recall and reminder systems have been created and shown significant improvement in increasing vaccination compliance rates[2]

Contraindications

Contraindications to immunization are rare.

  • The primary contraindication is an allergy to a vaccine or a component of the vaccine.
  • Patients with a history of a compromised immune system, such as in AIDS or another immune deficiency, should use caution when vaccinating with a live attenuated vaccine.
  • Live attenuated vaccines should not be given to a pregnant woman, unless there is an immediate risk (such as a polio epidemic), as the live vaccines have the potential to infect the fetus.
  • Caution should be used when administering a vaccine to a child with an acute moderate to severe illness, with or without a fever. The cause of fever following vaccination in this population may be difficult to determine, whether it be continued illness or directly resulting from the vaccination. This may complicate the management of the illness.[2]

Administration

  • Most human vaccines are administered by injection, although this approach is risky in the developing world where the use of injections can transmit diseases such as HIV infections.
  • Live vaccines can be given orally but not killed vaccines.
  • Alternatively, the use of the oral route and other mucosal surfaces have been explored as immunization route. For example, polio vaccination underwent a successful implementation via the oral route[7].

References

  1. 1.0 1.1 WHO Vaccines Available from:https://www.who.int/topics/vaccines/en/ (last accessed 6.6.2020)
  2. 2.0 2.1 2.2 Ginglen JG, Doyle MQ. Immunization. InStatPearls [Internet] 2018 Oct 27. StatPearls Publishing. Available from:https://www.ncbi.nlm.nih.gov/books/NBK459331/ (last accessed 6.6.2020)
  3. CDC Vaccines Available from:https://www.cdc.gov/vaccines/basics/test-approve.html (last accessed 6.6.2020)
  4. Youreka Vaccine clinical trial Available from:https://www.youtube.com/watch?v=R4AUGdT3DE8&app=desktop (last accessed 6.6.2020)
  5. NYT Corona virus vaccine Available from:https://www.nytimes.com/interactive/2020/04/30/opinion/coronavirus-covid-vaccine.html (last accessed 6.6.2020)
  6. ASCPY Development Times and Approval Success Rates for Drugs to Treat Infectious Diseases https://ascpt.onlinelibrary.wiley.com/journal/15326535 (last accessed 6.6.2020)
  7. Vaillant AA, Grella MJ. Vaccine (Vaccination). InStatPearls [Internet] 2019 Oct 21. StatPearls Publishing.Available from:https://www.statpearls.com/kb/viewarticle/30924 (last accessed 6.6.2020)