A Study to Evaluate the Long-Term Effect of TEV-48574 in Moderate to Severe Ulcerative Colitis or Crohn's Disease

The primary objective of the study is to evaluate the efficacy of 2 different maintenance dose regimens of TEV-48574 subcutaneous (sc) administered every 4 weeks (Q4W) in adult participants with inflammatory bowel disease (IBD). Secondary objectives of the study are to: * evaluate the efficacy of 2 different maintenance dose regimens of TEV-48574 sc administered Q4W in adult participants with IBD * evaluate the safety and tolerability of 2 different maintenance dose regimens of TEV-48574 sc administered Q4W in adult participants with IBD * evaluate the immunogenicity of 2 different maintenance dose regimens of TEV-48574 sc administered Q4W in adult participants with IBD The total duration for a participant in the double-blind period only is 66 weeks; and for a participant in the open-label extension (OLE) period, up to an additional 268 weeks.

Inclusion Criteria: * Maintenance Period- Participants who achieved clinical response and/or clinical remission at week 14 of TV48574-IMM-20036 (the 14-week DRF study) or in the re-induction period of this study. * Re-induction- Participants who did not achieve clinical response and/or clinical remission at week 14 of the TV48574-IMM-20036 DRF study NOTE- Additional criteria may apply, please contact the investigator for more information Exclusion Criteria: * Participants who discontinued the TV48574-IMM-20036 study before scheduled week 14 visit (any reason including lack of efficacy, safety, or personal reasons) * Participant has any concomitant conditions or treatments that could interfere with study conduct, influence the interpretation of study observations/results, or put the participant at increased risk during the study as judged by the investigator and/or the clinical study physician. * Participant anticipates requiring major surgery during this study. * Participant is currently pregnant or lactating or is planning to become pregnant or to lactate during the study or for at least 50 days after administration of the last dose of IMP in case of early termination. Any woman becoming pregnant during the study will be withdrawn from the study. NOTE- Additional criteria apply, please contact the investigator for more information