Analysis of factors involved in the development of humoral response to vaccination against SARS-CoV-2 in patients with rheumatic pathology under biological treatment

Background and objective

In the context of the SARS-CoV-2 pandemic, the development of new vaccines and their efficacy in patients with immune-mediated rheumatic diseases has been a target to investigate. The objective of this study is to evaluate the vaccine response rate in patients with immune-mediated rheumatic diseases under treatment with immunomodulators, including rituximab (RTX), as well as the influence of possible factors involved in the vaccination response in these patients.

Material and methods

A single-centre, prospective cohort study was conducted in 130 patients with immune-mediated rheumatic disease on treatment with immunomodulators, including RTX, who received the full course of vaccination against SARS-CoV-2 with BioNTech/Pfizer, Moderna/Lonza, AstraZeneca, or Janssen between April and October 2021. Demographic factors such as age, sex, type of immune-mediated disease, immunomodulatory treatment and type of vaccine were analysed, as well as serological markers including anti-SARS-CoV-2 IgG antibody levels measured one and six months after vaccination, CD19+ lymphocyte levels and the presence or absence of hypogammaglobulinemia. A statistical analysis was performed to assess the influence of the different variables collected in the study on the antibody titres.

Results

A sample of 130 patients was studied, 41 under treatment with RTX and 89 with other immunomodulators. A lower vaccination response rate was observed in patients with RTX (12/34, 36.7%) one month after the primary vaccination compared to 96.5% (82/85) of patients who did not receive this drug and did respond. In the analysis of secondary variables, hypogammaglobulinemia was significantly associated with lack of development of a vaccine response. The administration of the last RTX cycle in the 6 months prior to vaccination and low CD19+ levels (<20 mg/dL) also had a negative influence on the development of a vaccine response. In the group of patients who were not receiving RTX treatment, the vaccination response was like that observed in the general population. We did not observe statistically significant differences in the vaccine response based on immunomodulatory treatment other than RTX, concomitant corticosteroid treatment, type of immune-mediated pathology, age, or sex.

Discussion and conclusions

In patients with rheumatic diseases receiving immunomodulatory treatment, the response to vaccination against SARS-CoV-2 is comparable to the general population, except in the case of patients receiving RTX, who have a lower response rate (around 36.7%) which is associated with factors such as hypogammaglobulinemia, pre-vaccination CD19+ lymphocyte levels, and a period between vaccination and the last dose of RTX of less than 6 months. It is important to take these factors into consideration to optimize vaccination in these patients.