Efficacy and Safety of Mepolizumab in Adults With Chronic Rhinosinusitis With Nasal Polyps (CRSwNP)/ Eosinophilic Chronic Rhinosinusitis (ECRS)

Inclusion Criteria: * Participants of 18 years of age and older inclusive, at the time of signing the informed consent. * Body weight greater than or equal to 40 kilograms (kg). * Male or female participants (with appropriate contraceptive methods) to be eligible for entry into the study. * Female participant is eligible to participate if she is not pregnant or breastfeeding, one of the following conditions applies: * Is a woman of non- childbearing potential (WONCBP) : or * Is a woman of child bearing potential (WOCBP) and using a contraceptive method that is highly effective \[with a failure rate of less than (\<)1percent (%) per year\], preferably with low user dependency, during the study intervention period and for at least 105 days after the last dose of study intervention. The investigator should evaluate the potential for contraceptive method failure (for example \[e.g.\] noncompliance, recently initiated) in relationship to the first dose of study intervention. * A WOCBP must have a negative highly sensitive urine pregnancy test within 24 hours before the first dose of study intervention. * If a urine test cannot be confirmed as negative (e.g., an ambiguous result), a serum pregnancy test is required. In such cases, the participant must be excluded from participation if the serum pregnancy result is positive. * The investigator is responsible for review of medical history, menstrual history, and recent sexual activity to decrease the risk for inclusion of a woman wi…