IFNB1 and infection: Before adjusting for differences in patient characteristics, the incidence rate of serious infections was similar for patients treated with IFN-β and GA (incidence rate, 8.9 [95% CI 6.4–12.1] per 1000 person-years), and natalizumab (11.4 [95% CI 8.3–15.3] per 1000 person-years).