The platform trial in COVID-19 priming and BOOsting (PICOBOO): The reactogenicity of nine licensed COVID-19 vaccines delivered in immunocompetent adults.

Background

PICOBOO is a randomised, Bayesian adaptive trial evaluating immunogenicity and reactogenicity of licensed COVID-19 vaccines in immunocompetent individuals aged >12 years. We present reactogenicity data for nine vaccines administered as additional doses within adult strata based on age cohort and primary vaccination regimen.

Methods

Individuals who had not received a COVID-19 vaccine within three months were eligible. Participants were randomised within each stratum to receive a single vaccine dose. Reactogenicity events were recorded on days 1-7 following vaccination. Serious or medically attended adverse events (AEs), AEs of special interest, and AEs resulting in withdrawal were collected through day 28. Participants were followed until day 720.

Findings

A total of 1049 COVID-19 vaccine doses were administered to 586 adults enrolled between March 2022 and September 2024. Of these, 335 (57%), 96 (16%), 97 (17%) and 58 (10%) were randomised one, two, three and four times, respectively. At least one local reaction was reported after 786 (75%) doses and at least one systemic reaction after 798 (76%) doses. Local reactogenicity ranged from 47% (110/236) with NVX-CoV2373 (Nvx) to 90% (131/145) with Moderna, while systemic reactogenicity ranged from 69% (162/236) with Nvx to 85% (121/143) with BNT162b2. Pain was the most common local reaction; headache, fatigue, myalgia, and chills were the most common systemic reactions. Severe reactogenicity events were rare.

Interpretation

Reactogenicity events were common but rarely severe. Although reactogenicity appeared less frequent following Nvx than mRNA vaccines within strata, the trial was not powered for between-vaccine comparisons and findings should be interpreted descriptively.

Funding

Medical Research Future Fund (2014690/2016473) and The Snow Foundation.