This study aims at evaluating the immunogenicity and safety of two "reinforced" innovative pneumococcal vaccine regimen [one double dose at day0 and one double dose at day7 or a quadruple dose of 13-valent anti-pneumococcal conjugate vaccine (PCV13) followed by one dose of 23-valent unconjugated vaccine (PPV23) at month 5], compared to the standard regimen (one dose of PCV13 followed by one dose of PPV23 at month 5), in patients with ANCA-associated vasculitides receiving rituximab therapy.