How does vaccine testing work?

As mentioned previously, vaccines have to go through a variety of different testing stages before being certified as ready for the general public. The standard for testing new vaccines is one of the most robust in the medical field because vaccines are one of only a few treatments given to people who are otherwise healthy. At the end of the day, making healthy people sick from side effects is no better than allowing them to get the illness in the first place.

 Vaccine Development

The UK government and medical manufacturers have already stated that the full review process for creating a COVID-19 vaccine is going to be severely contracted to expedite vaccine production. But there are still quite a lot of hoops to go through. After initial ‘in vitro’ testing using individual human and animal cells and ‘in vivo’ testing, using live animals (usually mice), the vaccine will go into the initial trial phase where a small group of adults will be given the medication to see if it works and to test for side effects. This is the stage the Oxford University vaccine is currently at. Once this is successful the trial will be expanded to a larger group (several hundred people) and once again monitored for its effectiveness and side effects. The final stage will see several thousand people get the test. With COVID-19 this final phase may form part of the vaccines initial roll out to healthcare officials and those at risk.

Other articles in this series:

What is a vaccine?

When will there be a vaccine?

Vaccine development progress (live)


While we strive to provide accurate information at the time of writing, the rapidly evolving nature of the pandemic may mean that there are some inaccuracies. Please refer to GOV.UK for the latest information.

It is strongly recommended that speak to your doctor if you have questions about vaccines and/or COVID-19.