Who can volunteer?
Anyone who considers themselves healthy can join the
Every trial will have specific criteria that define who can and
who can’t take part, and these are in place mainly to ensure the
safety of participants. There are a few that apply to all trials in
There is almost always an upper age cut-off. This is partly
because the chance of a silent medical condition increases with
age, and partly because the immune responses decrease with age. In
vaccine trials, we are able to see how well the vaccine is working
to stimulate your immune system by testing participant’s blood in
the laboratory. We want to give the test vaccine the best chance in
the first trials, and so usually target younger people (less than
You need to be 18 or more, as 18 is the legal age at which you
can sign your consent to a medical procedure in the UK.
If you are female, or male and have a female partner, you need
to be using contraception that works for you as a couple and be
willing not to conceive while you are exposed to the test product,
and in the case of vaccines for a few months after the last one.
This is standard practice for all drug development.
Although you might be perfectly healthy, we could be concerned
if you are taking drugs to control a chronic medical condition.
When testing new products, we have less information about the
interactions with licensed drugs (usually no information), and so
we tend to say that anyone taking regular medication can’t take