Project #174:
ECHO - Evaluation of Covid-19 vaccine Histories using OpenSAFELY

COVID-19 vaccines reduce illness and save lives. Before any vaccines are approved for use in the general population, they are carefully tested in a small number of people (up to a few thousand), to assess how well they work and how safe they are. However, once vaccines are approved for use, millions of people will receive them, including people who differ in important ways from those who were included in the experiments. It’s therefore important to continue to assess how well the vaccines work in these “real world” settings.

We want to find out whether the chances of becoming seriously ill due to COVID-19 are affected by the time between booster vaccine doses and the type of vaccine received. We also want to know whether this varies in different groups of people. This will support future decisions about not just who gets vaccinated but when and with what type of vaccine. In this way we can better prevent illness due to COVID-19. Finding out the best way to use vaccines will also improve our preparedness for this and future pandemics.

We will describe when and what type of vaccines were received and how this varied in different groups of people. We will investigate what characteristics predict differences in vaccine timing, beyond simply whether a person was invited to be vaccinated at that time or not. We will also compare the rates of illness in people with different times between vaccine doses and different vaccine and different vaccine types.