Waning humoral immunity of SARS-CoV-2 vaccination in a rheumatoid arthritis cohort and the benefits of a vaccine booster dose.

OBJECTIVES

We aimed to assess SARS-CoV-2 spike-specific antibody kinetics postvaccination and the benefit of a mRNA vaccine booster dose in rheumatoid arthritis (RA) patients treated with immunosuppressive drugs.

METHODS

Consecutive RA patients on immunosuppressive therapies, with no known history of SARS-CoV-2 infection or high-risk contact, vaccinated with 2 doses SARS-CoV-2 mRNA, BNT162b2 or mRNA-1273, or viral vectored ChAdOx1 nCoV-19 vaccine were recruited during their routine rheumatology consultation. Anti-SARS-CoV-2 IgG spike-specific antibodies were quantified at 1, 3 and 6 months respectively following the second vaccine dose. The incidence of SARS-CoV-2 infection post-vaccination during this 6-month longitudinal study was also assessed.

RESULTS

Of the 104 RA patients included, 79 patients completed the 6-month trial follow-up. A significant decrease in anti-SARS-CoV-2 spike-specific IgG titres was observed between 1-month and 3-month postvaccination (p<0.01). Among the 46 patients (46/79) receiving a booster dose, all developed detectable anti-SARS-CoV-2 spike-specific IgG antibodies at the 6-month follow-up with significantly higher titres compared to 1-month (p<0.001) and 3-month (p<0.0001) post-vaccination. Conversely, the antibody titres among the 33 patients (33/79) not receiving a booster dose decreased significantly at the 6-month follow-up compared to 1-month (p<0.0001) and 3-month (p<0.01) post-vaccination. The incidence of COVID-19 disease postvaccination was 8.9% without severe forms.

CONCLUSIONS

To our knowledge, this is the first study to report on anti-SARS-CoV-2 spike-specific antibody kinetics postvaccination and the effect of a booster dose in a cohort of RA patients. The latter is essential given the waning humoral immunity observed in vaccinated RA patients and the increased incidence of COVID-19 diseases postvaccination in this 6-month longitudinal study.