Influenza A/H1N1 vaccination of patients with SLE: can antimalarial drugs restore diminished response under immunosuppressive therapy?

OBJECTIVE To assess the efficacy and safety of pandemic 2009 influenza A (H1N1) in SLE under different therapeutic regimens. METHODS A total of 555 SLE patients and 170 healthy controls were vaccinated with a single dose of a non-adjuvanted preparation. According to current therapy, patients were initially classified as SLE No Therapy (n = 75) and SLE with Therapy (n = 480). Subsequent evaluations included groups under monotherapy: chloroquine (CQ) (n = 105), prednisone (PRED) ≥20 mg (n = 76), immunosuppressor (IS) (n = 95) and those with a combination of these drugs. Anti-H1N1 titres and seroconversion (SC) rate were evaluated at entry and 21 days post-vaccination. RESULTS The SLE with Therapy group had lower SC compared with healthy controls (59.0 vs 80.0%; P < 0.0001), whereas the SLE No Therapy group had equivalent SC (72 vs 80.0%; P = 0.18) compared with healthy controls. Further comparison revealed that the SC of SLE No Therapy (72%) was similar to the CQ group (69.5%; P = 0.75), but it was significantly reduced in PRED ≥20 mg (53.9%; P = 0.028), IS (55.7%; P = 0.035) and PRED ≥20 mg + IS (45.4%; P = 0.038). The concomitant use of CQ in each of these later regimens was associated with SC responses comparable with SLE No Therapy group (72%): PRED ≥20 mg + CQ (71.4%; P = 1.00), IS + CQ (65.2%; P = 0.54) and PRED ≥20 mg + IS + CQ (57.4%; P = 0.09). CONCLUSION Pandemic influenza A H1N1/2009 vaccine response is diminished in SLE under immunosuppressive therapy and antimalarials seems to restore this immunogenicity. Trial registration. www.clinicaltrials.gov, NCT01151644.