Higher Human Biology Unit 3 – Neurobiology and Immunology Section 24 – Clinical Trials of Vaccines and Drugs

Clinical trials of Vaccines and Drugs We will be learning… To describe how vaccines and drugs are subjected to clinical trials to establish that they are safe and effective before being licensed for use. To describe the design process of clinical trials to test vaccines and drugs e.g. randomised, double-blind and placebo-controlled protocols. To explain the importance of group size in reducing experimental error and establishing statistical significance.

What is a Vaccine? The pathogen is mixed with an adjuvant An adjuvant is a chemical which increases the antigenic response, enhancing the immune system Types of vaccines include inactivated pathogen toxins (tetanus and diphtheria), dead pathogens (polio and hepatitis A), parts of pathogens (HPV and hepatitis B) weakened pathogens (measles, mumps and rubella).

How does a Vaccine Work? Vaccines contain either antigens of disease causing microorganisms or an inactivated form of the complete microorganism. If we inject these into the blood, they are unable to cause disease, but do help our immune system to build up memory immunity. If then, we are infected with a complete, disease causing microorganism the B memory cells will be ready to spring a quick response and clear the invading pathogen.

How are Vaccines Tested? A Vaccine is tested by clinical trial A clinical trial is a type of medical research. It aims to find new and improved ways of preventing diagnosing Treating controlling illnesses. People are involved in the trial in a controlled and carefully planned way.

Clinical Trials Clinical trials are designed to answer questions - about a treatment or a procedure. The main questions are usually: Does it work? Is it safe? Does it cause side effects? How does it affect quality of life? Does it work better than existing treatments? What is the best dose to use?

What Makes a Vaccine Safe? Before a licence can be issued for a vaccine or a drug to be administered to the public, it must be subjected to an intensive series of trials to establish its safety and efficacy. In advance of any human trials, the vaccine must undergo extensive laboratory research, including tests on cell cultures and laboratory animals. These pre-clinical trials allow vaccine researchers to gain a better understanding of how the treatment works and of any side effects. Protocols must be drawn up at this stage for the trials, these may include: target groups for the trials; number of subjects involved in these trials; other treatments with which to be compared; procedures for collection and interpretation of data.

How are Vaccines Designed? Vaccines are subjected to clinical trials just like any other pharmaceutical medicine They must be shown to be safe and efficacious (effective when used in humans)

What Makes a Vaccine Effective? Vaccine efficacy is the percentage reduction of disease in vaccinated group of people compared to an unvaccinated group, using the most favourable conditions.

Randomised Vaccine Testing Randomised Testing - all subjects in the trial have an equal chance of being given the vaccine or the placebo

Placebo-Controlled Vaccine Testing Placebo-Controlled Testing - the subjects are divided into two groups, one receiving the vaccine and the other receiving the placebo, a treatment which is similar in all respects to the vaccine apart from the active ingredient being tested. People can sometimes feel better when they have a placebo because they think they are having a real treatment. This is known as the 'placebo effect'.

Double-Blind Vaccine Testing Double-Blind Testing - neither the subjects nor the scientists carrying out the trial know which subjects are getting the vaccine and which the placebo In a blinded trial, you won't know whether you are getting the trial treatment, or the standard treatment or placebo. They will both look the same. Trials need to be 'blind' because just knowing that you are getting a new treatment can affect how you respond to, and make the results unreliable.

Why is Group Size important in Minimising Experimental Error New drugs that are to be manufactured for public use must be tested on a large scale in order to ensure that the positive results from the small initial human tests are reliable.

Statistical Significance in Testing At the end of the trial, results from the groups (control/placebo/double-blind trials) must be of a suitable size to reduce the magnitude of experimental error. They are compared to determine whether there are any statistically significant differences between the groups

Clinical trials of Vaccines and Drugs Now I can….. Describe how vaccines and drugs are subjected to clinical trials to establish that they are safe and effective before being licensed for use. Describe the design process of clinical trials to test vaccines and drugs e.g. randomised, double-blind and placebo-controlled protocols. Explain the importance of group size in reducing experimental error and establishing statistical significance.

Word Description Natural Immunity immunity which is acquired by natural means, e.g. catching a cold Mortality rate death rate, often expressed as a number of deaths per thousand of the population Innate immunity immunity which is inborn immunity the ability to resist infection by pathogens Humoural response the production of antibodies by B-lymphocytes Vaccination using an antigen that has been made harmless to produce an immune response and memory cells Randomised describing protocols in clinical trials that are the result of chance selection Placebo-controlled protocol procedure that involves giving certain participants a blank instead of the drug under trial Double-blind protocol method in which neither trial participant nor experimenter knows the treatment given

Word Description Clinical trials methods of obtaining data about new drugs or treatments Adjuvant substance added to a vaccine to enhance the immune response Vector organism organism that can carry or transfer a stage of a disease parasite into the body Pathogen biological agent of disease, such as bacterium, virus, protozoan or fungus

D Also try - 2016 – Q11