ABSTRACT
Next to providing clean water, vaccination is the most effective intervention to prevent death and suffering from infectious diseases. The COVID-19 crisis starting in late 2019 painfully demonstrates the challenges of controlling a pandemic without vaccines. The enormously beneficial potential of vaccination to improve public health and reduce health inequalities can best be realised by delivering vaccines as part of a planned vaccination programme. Effects of vaccines are extensively studied in pre-clinical and clinical trials prior to their use in vaccination programmes. The primary purpose in the evaluation of a vaccination programme is to assess whether the programme is meeting its aims. Vaccination programmes achieve their aims by altering the epidemiology of vaccine-preventable diseases. Epidemiology is therefore the main tool for studying the interactions between vaccination programmes and human populations: the epidemiology of vaccination programmes is about investigating, in real conditions of life, the impacts, benefits and risks of such programmes.
