Immune responses to COVID booster vaccination; results of an UK-wide clinical trial


Pictured the Cov-BOOST Cambridge team

On behalf of the NIHR Cambridge Clinical Research Facility, its Director, Professor Krishna Chatterjee said: “We are pleased to participate in the UK-wide trial COV-BOOST, which has evaluated the safety, immune responses and side-effects of seven different COVID-19 vaccines when used as a third vaccination, commonly known as a booster dose”.

In this trial, which was led by University Hospital Southampton NHSFT, nearly 3,000 people were given a booster jab 10 to 12 weeks after their initial two-dose vaccination with either the AstraZeneca or Pfizer-BioNTech vaccine.

The results, published in The Lancet in December 2021, showed that all seven vaccines are safe to use as a third dose. Most vaccines boosted the levels of spike protein antibodies significantly, but there were large differences in these levels between people who had first received two doses of AstraZeneca compared to those first receiving two doses of the Pfizer-BioNTech vaccine.

Results for the different boosters were similar within two age groups, those aged 30 to 69 years and those aged 70 years or older. The study also reported significant immune T-cell responses to several combinations of initial and booster vaccines, but these were not predictable based on spike protein antibody levels.

Although describing immune responses at 28 days, the data has provided confidence and flexibility in developing booster programmes both nationally and globally. The trial will be looking at longer-term immune responses at three months and one year after receiving boosters, and was designed so that stored samples can be used in evaluating the effectiveness of these vaccines in neutralising new variants of concern. COV-BOOST samples have been made available to the UK Health Security Agency for testing against the Omicron variant.