How are vaccines made?
The development of a new vaccine follows on from extensive scientific research on the disease and the virus, bacteria or parasite (microbe) that cause it. This know-how allows researchers to understand how the body’s defences respond to an infection and how to help it prepare. Vaccines are designed, tested and manufactured according to strict regulations. All vaccines undergo rigorous testing to demonstrate they are sufficiently safe and effective before they can be used more widely.
Scientists must identify which vaccine technology (See What different types of vaccines are there?) is likely to be most appropriate for the infection and who will benefit most from it. A possible new vaccine will undergo extensive testing in animals (called pre-clinical testing) to examine its safety along with information on how effective it might be at getting our immune systems to respond.
A new vaccine must then go through three phases of clinical testing in progressively larger groups of human participants. These are designed to look for any potential side-effects and safety concerns, to work out the best dose and number of doses required, to demonstrate the immune response and examine how well the vaccine protects against the disease. By the end of these trials, the vaccine will have been tested in at least 3,000 people (each of the Covid19 vaccines were tested in more than 25,000 people before they were licensed).
The data from each stage of testing is then passed to national regulating authorities, such as the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK, the European Medicines Agency (EMA) or the US Food and Drug Administration (FDA). Scientists and medical doctors examine the data from the trials, alongside manufacturing and quality control data, to decide whether a vaccine can then be approved – or licensed – for use.