Six Covid-19 vaccines are safe and boost immunity for people who have had two doses of AstraZeneca or Pfizer-BioNTech, results from the UK-wide COV-BOOST trial show.

The world-first study, for which Public Health Wales recruited volunteers at the North Wales Clinical Research Facility based at Wrexham Maelor Hospital, was key to shaping the UK booster programme and gives vital evidence for global vaccination efforts.

The trial looked at the safety, immune responses and side-effects of seven vaccines when used as a third, booster jab.

There were 164 volunteers who joined the study from across the Wrexham area.

Run at 18 sites across the UK, the study saw 2,878 people aged 30 or over recruited. Participants received one of these boosters 10-12 weeks after their initial two-dose vaccination with either AstraZeneca or Pfizer-BioNTech.

The seven vaccines trialled were:

  • AstraZeneca-Oxford
  • Pfizer-BioNTech
  • Moderna
  • Novavax
  • Valneva
  • Janssen
  • CureVac

Of these, only AstraZeneca, Pfizer-BioNTech, Moderna and Janssen are currently licensed for use in the UK.

Professor Saul Faust, trial lead and director of the NIHR Clinical Research Facility, University Hospital Southampton NHS Foundation Trust (UHS), said: “Our side effect data shows all seven vaccines are safe to use as a third dose, with acceptable levels of ‘reactogenicity’ – inflammatory side effects like injection site pain, muscle soreness, fatigue. All seven boosted levels of spike protein antibodies significantly after two doses of AstraZeneca. However only six also did so after two doses of Pfizer-BioNTech. There were also large variations in response with different boosters.

“It’s really encouraging that a wide range of vaccines, using different technologies, show benefits as a booster dose to either of these vaccines. That gives confidence and flexibility in developing booster programmes here and globally, with other factors like supply chain and logistics also in play.”

Reactions to all seven vaccines were similar, with fatigue, headache, and injection site pain most often reported. These were more commonly reported by those aged 30-69.

While 912 of the 2,878 participants experienced a total of 1036 adverse events, only 24 of which were severe.

Dr Orod Osanlou, Consultant Physician and Principal Investigator for Public Health Wales and the COV-BOOST study said: “We are proud that the North Wales Clinical Research Facility has supported such an important, world-first study. This will inform the future rollout of the Covid-19 vaccination programme across Wales and internationally.

“I would like to thank all of our study participants and staff across Betsi Cadwaladr University Health Board who made this research possible, contributing to the UK-wide effort to tackle the pandemic.”