aPML risk is inferred from the estimated US incidence. The risk estimates are based on postmarketing data in the United States from approximately 100,000 TYSABRI-exposed patients. The anti-JCV antibody status was determined using an anti-JCV antibody test (ELISA) that has been analytically and clinically validated and is configured with detection and inhibition steps to confirm the presence of JCV-specific antibodies with an analytical false-negative rate of 3%.
bAs of June 2020.