Evaluating COVID-19 Vaccine Boosters

A randomised, phase II UK multi-centre study to determine reactogenicity and immunogenicity of booster vaccination against ancestral and novel variants of SARS-CoV-2.

Closed to recruitment

Aim of the study

This study is trying to determine the side effect profile, safety and immune response of giving different 3rd COVID-19 vaccine doses of BNT162b2 (Pfizer) and mRNA-1272 (Moderna) to people who have previously received 2 doses of BNT162b2 (Pfizer) or mRNA-1272 (Moderna). We will be enrolling men and women aged 18 to 30 years old who have had

Eligibility criteria

Participant is willing and able to give written informed consent for participation in the trial.

  • Male or Female, aged 18 to 30 years and in good health as determined by a trial clinician. Participants may have well controlled or mild-moderate comorbidity.
  • In the Investigator’s opinion, is able and willing to comply with all trial requirements.
  • Willing to allow their General Practitioner and consultant, if appropriate, to be notified of participation in the trial
  • Willing to allow investigators to discuss the volunteer’s medical history with their General Practitioner and access all medical records when relevant to study procedures.
  • Agreement to refrain from blood donation during the study.
  • Has received 2 doses of BNT162b2 or mRNA-1273 and is at least 3 months (84 days) since their second dose by day 0

What participating in the study involved

Participants will be randomised to receive either a single dose of the BNT162b2 (Pfizer) vaccine (30mcg), one third of the normal dose of BNT162b2 (10mcg, the same dose being used in other countries for children aged 5 – 11 years), a half dose of the mRNA-1273 (Moderna) vaccine (50mcg, the dose being used by the NHS as a 3rd dose booster) or one quarter of a dose of the mRNA-1273 vaccine (25mcg). They will then complete a diary of their symptoms over the next 7 days, and any other adverse events which occur up to 3 months after having had the vaccine. There are several follow up visits to have blood tests to check for immune markers, and to check on the participants health.

Participants will initially be “blinded”, meaning they will not be told which vaccine they have been given until after they have attended a follow up visit 84 days after being vaccinated. If a participant is travelling to a country with a requirement for a third dose of COVID-19 vaccine for entry prior to their day 84 follow up visit there will be a process to unblind them before the day 84 follow up visit if there is an urgent need and they have attended the follow up visit that is 28 days after vaccination. Any internal UK certification system for a COVID-19 third dose will provide exemption for people taking part in COVID vaccine trials, as for the first 2 doses.