Six Covid vaccines safe and effective when used as boosters
It follows research led by teams in Southampton
Last updated 27th May 2022
Six Covid-19 vaccines are safe and boost immunity for people who have had two doses of AstraZeneca or Pfizer, according to the results of a major Southampton-led trial.
The UK-wide COV-BOOST trial, led by the University Hospital Southampton NHS trust, has been cited in influencing the JCVI's decision to cut the time between administering second and third doses of a jab from six months to three months earlier this month.
More than 2,800 volunteers aged 30 or older took part in the research, which looked at the safety, immune responses and side-effects of seven vaccines when used as a third booster jab.
Those taken part were given one of seven vaccines - Oxford-AstraZeneca, Pfizer-BioNTech, Moderna, Novavax, Valneva, Janssen and CureVac - 10-12 weeks after their initial two-dose vaccination.
A control group was given a meningitis vaccine, to account for reactions not specific to the COVID-19 jabs.
It's hoped the results of the trial will allow for greater flexibility in giving booster jabs out in the UK - potentially freeing up more jabs to be used in less developed countries at a much earlier stage of the vaccine rollout.
Professor Saul Faust, trial lead and Director of the NIHR Clinical Research Facility at 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 (AstraZeneca, Pfizer-BioNTech, Moderna, Novavax, Janssen and CureVac). 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."
The levels of spike protein antibodies after 28 days were found to range from 1.8 times higher to 32.3 times higher with different booster vaccines after two doses of the AstraZeneca vaccine.
For those who had received Pfizer-BioNTech initially, the range was 1.3 times higher to 11.5 times higher.
The research also found that all seven of the vaccines tested boosted levels of immune T-cells, which can control the severity of the disease.
Although the research was conducted before the discovery of the Omicron variant, the results found all vaccines were effective against all variants of the virus discovered to that point, raising hopes they can help to fight Omicron as well.
Kate Hedger, a former radiographer from Fareham in Hampshire, was one of those who took part in the study - just weeks after retiring as a frontline worker.
She said:
“As a healthcare professional I had my COVID-19 vaccinations quite early on so I thought I might be eligible to take part.
“It sounds really cliche to say but I wanted to do my bit, I wanted the trial to be a success.
“I didn’t want to retire and have no knowledge of what’s going on and I felt that being a part of this trial helped with this.
“It was nice to be given the opportunity to take part in the trial and I feel so proud of it all being local to me."
Prof. Saul Faust added:
“We will be looking at the longer-term immune responses in COV-BOOST, conducting further tests at three months and one year after receiving boosters.
“We are also looking at whether a longer period between second and third doses improves response to the two of the booster vaccines. Several studies have shown this effect between first and second doses.
"We’ve done that by giving some of our original control participants the booster at a later point, and we expect those results to be available in the new year.”