Methods: One hundred thirty-four adult patients [RA (n=45), AS (n=61), PsA (n=28)] under anti-TNF agents (62 infliximab, 43 adalimumab and 29 etanercept) regularly followed in our Rheumatology Division and 125 age-matched healthy controls were vaccinated with a non-adjuvanted preparation of influenza A/California/7/2009 (H1N1) virus-like vaccine. All participants were evaluated pre- and 21 days post-vaccination and serology for anti-H1N1 was performed by hemagglutination inhibition (HI) assay. Seroprotection (HI antibody titer≥1:40), seroconversion (percentage of subjects with either a pre-vaccination HI titer < 1:10 and a post vaccination HI titer ≥ 1:40 or a pre-vaccination HI titer > 1:10 and a minimum four-fold rise in post-vaccination HI antibody titer) rates, geometric mean titres (GMTs) and factor increase (FI) in GMT (ratio of the GMT after vaccination to the GMT before vaccination) were calculated. The effect of concomitant drugs on vaccine response was assessed and adverse events were also evaluated.
Result: Patients and controls had comparable mean current age (43.8±13.1 vs. 45.7±12.2 years, p=0.233). Three weeks after immunization, seroconversion (61.2% vs. 70.4%, p=0.119) and seroprotection rates (64.9% vs. 75.2%, p=0.072) were similar in both groups, whereas the FI in GMT was significantly lower (7.29 vs. 11.54; p=0.0089) in patients versus controls. The assessment of the influence of concomitant use of other drugs in patients under anti-TNF showed a trend of a higher frequency of seroconversion rate in patients under diphosphate chloroquine compared to those without it (90.9% vs. 58.5%, p=0.05), but association with other drugs, such as prednisone, methotrexate and leflunomide did not interfere in the response (p>0.05). Local and systemic vaccine adverse events were mild and with similar frequencies in patients under anti-TNF and controls (p>0.05).
Conclusion: The overall immune response to influenza A H1N1/2009 in rheumatic disease patients under TNF blockage therapy is adequate with an excellent safety profile. (ClinicalTrials.gov, #NCT01151644)
Disclosure: I. L. A. França, None; A. C. M. Ribeiro, None; N. E. Aikawa, None; C. G. S. Saad, None; A. L. G. Calich, None; J. C. B. Moraes, None; I. Laurindo, None; J. Miraglia, None; M. A. Ishida, None; E. Bonfa, none, 2 ; C. Silva, none, 2 .