Explainer: Clinical Trials in Vaccine Development

Research

Development of treatments and interventions is not a walk in the park as it requires intense research, tests, trials, financing and time. It is very possible for an approved treatment to be withdrawn from the market – if the users experience adverse effects or if the manufacturer detects irregularities in the vaccine vials.

Research and development involve activities that lead to innovation and introduction of new and better products into the market. In the research and development cycle, testing and studying the efficacy of a proposed product is major in creation of new and efficient products. In relation to vaccine development, clinical trials are a crucial part in evaluating the effectiveness of a vaccine in priming the immune system against a particular disease agent.


What are clinical trials? According to the World Health Organization, clinical trials study new tests and treatments, evaluating their potential effects on human health outcomes. Persons are usually asked to volunteer for these clinical trials which helps to give a clear picture of what effects proposed drugs, devices and procedures have in the actually human body.

Clinical trials occur in a number of phases:

  1. Preclinical trials: This study is usually done on non-human subjects such human cells, mice and chimpanzees while adhering to ethical standards.
  2. Phase 0: Usually carried out on a small group of people to determine a few parameters of the treatment usually drugs, to evaluate bioavailability and half-life of the drug.
  3. Phase I: New drugs are tested for the first time in a small group of people to determine the safe dosage range and associated side effects.
  4. Phase II: Once the treatments are established to be safe within a particular dose range in phase I, phase II is carried out to monitor any adverse effects of the treatment.
  5. Phase III: this study is carried out on a large group of people and usually is a gateway to the approval of a treatment.
  6. Phase IV: This is the final stage of clinical trials that occurs after the treatment has been approved in a country and is usually carried out to study the long-term effects of the approved intervention.


Development of treatments and interventions is not a walk in the park as it requires intense research, tests, trials, financing and time. It is very possible for an approved treatment to be withdrawn from the market if the users experience adverse effects or if the manufacturer detects irregularities in the vaccine vials.

In relation to the ongoing global pandemic, scientists have been working around the clock to develop a safe and effective vaccine against COVID-19. There being no time to carry out extensive research to fully evaluate the acute side effects and long-term effects of corona virus vaccines, scientists are trying their best to quickly develop and evaluate effective vaccine formulas within a short time. A number of potential vaccine candidates include the pfizer/ BioNTech and Moderna vaccine with 95 percent effectiveness


Another promising vaccine is the Oxford AstraZeneca vaccine candidate also called ChAdOx1 nCoV-2019 with 70 percent efficiency which can go to 90 percent when the dose is tweeched. In the UK, Phase I and Phase II of the clinical trials have already been carried out and Phase III is ongoing. This is such a big deal because if the vaccine proves to be efficient and safe, then it might be approved by regulatory institutions such as the Food and Drug Administration in the US and other governments, for its use in preventing corona virus infection.

Recently, The Kenya Medical Research Institute (KEMRI) Wellcome Trust in Kilifi joined the COVID-19 vaccine research by beginning phase I clinical trials of the AstraZeneca and Oxford University COVID-19 vaccine. Phase I targets 40 health workers and Phase II targets 400 front line workers. After the volunteers are immunised, they will be observed for about a year to monitor their health, any side effects to the vaccine and lastly, how their body mounts an immune response in response to the vaccine.


Once Phase III of these clinical trials in different countries provide positive results, the stages of vaccine development that follow include regulatory review and approval followed by manufacturing and finally quality control. Phase IV can then begin after mass administration of the vaccine to help evaluate the long-term effects of the vaccine. One very important aspect of vaccine development is to carry out clinical research on different populations. This is because one cannot just assume that the response of the immune system observed in Africa will be identical to that observed in North America or Asia.


A potential treatment has to prove itself efficient in different populations and environments. The immune system is characteristic of genetics, age, previous infections and lifestyle factors thus the immune response produced by the vaccine cannot be assumed similar in all populations. The Oxford AstraZeneca vaccine candidate clinical trials are being conducted in Brazil, UK, USA, South Africa and recently Kenya. This will be beneficial in ensuring that the vaccine can be able to effectively trigger an immune reaction in different populations and environments.


Apart from studying the efficacy of vaccines, other valuable parameters such storage and temperature requirements should be evaluated. This is where the short coming of the Pfizer vaccine comes in. This vaccine requires ultra-low temperature storage, of about minus 70 degrees celcius, which is not easily achievable in all parts of the world. The Moderna vaccine candidate can be stored longterm in a normal freezer at minus 20 degrees celcius upto 6 months. On the contrary, the Oxford AstraZeneca vaccine can be stored within a range of 2 degrees celsius to 8 degrees celsius in a normal fridge temperature. This therefore makes the Oxford AstraZeneca vaccine a preferred vaccine option by many governments as it is cheaper in terms or storage while still being able to trigger significant immune responses against the virus.

Vaccines are by all means a better alternative for treatments and as much as they require a lot of resources in their research and development, it is all worth in the end because prevention is better than cure.

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