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CoronaVac, an inactivated SARS-CoV-2 vaccine, has been administered in over 100 countries worldwide, but its immunity wanes quickly over time.1 In consequence, boosters are being recommended.
We evaluated the immunogenicity of an mRNA vaccine booster (BNT162b2) in inflammatory arthritis (IA) patients with biologic treatments previously vaccinated with CoronaVac. Consenting adults with IA followed at Red Salud UC-CHRISTUS (Chile), who were on anti-TNF, anti-IL6 or anti-IL17 biologics, vaccinated with CoronaVac (0, 28), were eligible. Those with a SARS-CoV-2 infection history were excluded. Humoral response was assessed by measuring IgG SARS-CoV-2 total antibody (Tab) and neutralising antibody (Nab) within 7 days and 4 weeks after the booster. DMARDs were not discontinued.
The primary outcome was the proportion of participants with positive SARS-CoV-2 Nab 4 weeks after the BTN162b2 booster. A neutralisation of 30% or more at a 1:10 dilution was considered positive.2 Dichotomous and continuous variables were compared using the McNemar or Wilcoxon signed-rank test. Confounding and effect modifiers of covariates were explored using binary regression models.
Seventy-six individuals were included. Mean age was 51.9 (SD 11.3) and 73.6% were female. Mean years since diagnosis were …
Footnotes
Handling editor Josef S Smolen
Contributors Authors report no competing interests, and all significantly contributed to this work. JD, MEB and MC: acquisition, interpretation of data, drafting the work and final approval of the version to be published. PIB, NLC, CRT, CM-V, VM and PN: acquisition, interpretation of data and drafting the work and final approval of the version to be published. All authors have agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding This work was supported by PANLAR Stimulus Award 2021, PANLAR.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.