The Speaker
Monday, 24 June 2024 – 07:13

Are vaccine trials safe?

An urgent appeal has been issued in the UK for volunteers to take part in human trials of a potential COVID-19 Coronavirus vaccine. Those who take part are to be offered up to £625, but some people have been asking how safe vaccine trails actually are.

This explainer takes a look at what trials are taking place, who can take part, and how safe vaccine trials are considered to be.


What trials are taking place?

Teams at both the University of Oxford and at Imperial College London are to each get at least another £20m of public money after making ‘rapid progress’ in the hunt for a COVID-19 vaccine, Health Secretary Matt Hancock said on Tuesday.

The University of Oxford are to begin trials on ‘healthy volunteers’ from Thursday.

Imperial College London are not yet screening participants, but hope to begin human trials on their vaccine in June.


What is the vaccine being trialled?

The vaccine being trialled by the University of Oxford is called ChAdOx1 nCoV-19. The vaccine is made from a harmless chimpanzee virus that has been genetically engineered to include part of the COIVD-19 virus. 

According to the university, researchers plan to recruit a total of 1,112 volunteers, and up to 561 of those will be vaccinated with ChAdOx1 nCoV-19. The other volunteers will be given a control vaccine which protects against meningitis and sepsis, as a comparison.

The vaccine trial will last around 6 months, with an optional visit one year after vaccination. It is hoped that results from the human trials could be available as soon as September.


Who can take part in the vaccine trials?

Volunteers for the trials must be aged 18 to 55 and in ‘good health’. Tests will be carried out at the University Hospital Southampton, the Bristol Children’s Vaccine Centre and the Imperial College London.

Volunteers for the trials must live in the city areas where the vaccines are being trialled.

Pregnant women are unable to take part, as are people who have tested positive for the Coronavirus or are considered at high risk from the virus.


How safe are the vaccine trials?

The vaccine being developed by the University of Oxford is made up of a weakened version of a common cold virus called the adenovirus. The adenovirus, which has been taken from chimpanzees, has been genetically altered so that it can’t replicate and grow in humans, according to the university. The virus has also been combined with genes that make proteins from the COVID-19 virus (SARS-CoV-2) called spike glycoprotein.

Early findings have shown that animals who are given the vaccine are able to produce neutralizing antibodies against the Coronavirus.

This is the first time the vaccine has been given to humans but similar vaccines have been “widely administered for many pathologies without significant safety concerns”, according to the university. There are some potential risks and side effects of the trials, stated as;

  • Slight pain and occasional bruising due to drawing blood for samples
  • Some mild redness and swelling from vaccine injections
  • Potential flu-like symptoms within 24 hours which are usually resolved within 48 hours.

The safety of vaccine trials can’t be guaranteed. Vaccines have to be trialled before they are licensed for use to try and find out any unexpected side effects or risks of their use.


How can I sign up to the trials?

If you would like to help with the trials and are eligible, you can sign up at

Skip to content