The effect of infliximab and timing of vaccination on the humoral response to influenza vaccination in patients with rheumatoid arthritis and ankylosing spondylitis

Objectives: To assess the effect of the timing of vaccination in relation to administration of infliximab on the efficacy and safety of influenza vaccine in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

Methods: The study population comprised 38 patients treated with infliximab at a mean dosage of 3 mg/kg (20 RA patients; 18 AS patients; 23 RA controls (treated with disease modifying antirheumatic drugs other than anti-tumor necrosis factor-alpha; and 17 healthy controls). Split-virion inactivated vaccine containing 15 mug hemagglutinin/dose of each of A/New Caledionan/20/1999 (H1N1), A/Wisconsin/67/2005 (H3N2), and B/Malaysia/2506/2004 (M) was used. Patients treated with infliximab were divided into 2 groups: 22 were vaccinated on the day of administration of infliximab, while 16 received the vaccine 3 weeks after infliximab. Baseline and 4- to 6-week clinical assessment of disease activity included erythrocyte sedimentation rate and C-reactive protein for all patients, the 28-joint disease-activity score for RA patients, and Bath Ankylosing Spondylitis Disease Activity Index for AS patients. Hemagglutination inhibition (HI) antibodies were tested by a standard World Health Organization procedure. Response was defined as >or=4-fold rise in HI antibodies 4 to 6 weeks after vaccination, or seroconversion in patients with a nonprotective baseline level of antibodies (<1/40). Geometric mean titers (GMT) were calculated to assess the immunity of the whole group.

Results: At baseline, RA patients and controls had similar occurrence of protective levels of HI antibodies and GMT, while AS patients had lower levels reflecting lower rates of previous vaccination. Four weeks after vaccination, a significant and similar increase in GMT for each antigen was observed in all groups (P < 0.004) except in the RA-infliximab group, vaccinated 3 weeks after administration of infliximab, in whom the increase in GMT was not significant for H1N1 (P = 0.12) and H3 (P = 0.06). AS patients demonstrated an increase in GMT, independently of the time of vaccination. The percentage of responders was similar in all groups. The response was not affected by variables such as age, gender, methotrexate, or prednisone use. Parameters of disease activity remained unchanged. No adverse effects other than injection site pain were recorded.

Conclusions: Influenza virus vaccine generated a good humoral response in RA and AS patients treated with infliximab.