• must have a documented diagnosis of Multiple Myeloma (MM)

-who recently started teclistamab within the first 8 weeks of their planned treatment schedule and are planned to receive teclistamab for the next 12 months.

The participant or the participant's legally acceptable representative has provided informed consent

The participant is at least 18 years of age at the time of signing the ICF.

If a person of childbearing potential engages in sexual relations that carry risk of pregnancy, they agree to the following for the period from screening until 30 days after the last dose of study drug:

To use a highly effective contraceptive method.To avoid donating ova.

-has not achieved at least a minimal response to teclistamab within 8 weeks during the screening period.

-has a current serious infection or greater than (>) 1 serious infection in the past 3 months before screening.

-has a documented polyclonal IgG level less than (<) 150 milligrams per deciliter (mg/dL) at the most recent assessment before teclistamab initiation (within 4 weeks) as assessed by the investigator according to the site's standard practice.

-currently receiving immunoglobulin products or has received immunoglobulin products within 16 weeks before screening.

-has received a hyperimmune or specialty high-titer immunoglobulin product (example, cytomegalovirus immune globulin, varicella-zoster immune globulin, hepatitis B immune globulin) within 30 days before screening.

• has received live viral vaccines within 30 days before screening.

-has an Eastern Cooperative Oncology Group performance status score of >2.

• has an active viral or bacterial infection or symptoms/signs of such an infection requiring treatment with anti-infectives within 1 week before enrollment.

-has received other B Cell Maturation Antigen (BCMA)*Cluster of Differentiation (CD3)-directed Bispecific Antibody therapy any time before screening.

-scheduled to undergo plasmapheresis during the course of study or has undergone plasmapheresis in the last 16 weeks before screening.

-may be excluded from the study if, in the opinion of the investigator, the participant is at high risk for symptomatic hyperviscosity syndrome.

-has major surgery scheduled during the study, or the participant has not fully recovered from a recent major surgery (as judged by the investigator) during screening (participants with planned surgical procedures to be conducted under local anesthesia may participate).

-has an active secondary (non-MM) malignancy or other medical condition with life-expectancy of less than (<) 2 years.

-has a known history of hypersensitivity or persistent reactions (urticaria, breathing difficulty, severe hypotension, or anaphylaxis) after Intravenous Immunoglobulin (IVIG) and/or immune serum globulin infusions.

-known history or current diagnosis of thromboembolic episodes such as deep vein thrombosis, pulmonary embolism, myocardial infarction, ischemic stroke, transient ischemic attack, peripheral artery disease within 6 months before screening.

• moderate to severe renal dysfunction based on an estimated glomerular filtration rate less than or equal to (<=) 30 milliliters per minute per 1.73 square meters (mL/min/1.73 m^2), as defined by kidney disease

-has a known history of or is positive at screening for one or more of the following: hepatitis B surface antigen, Polymerase Chain Reaction (PCR) for hepatitis C virus, PCR for Human Immunodeficiency Virus (HIV) Type 1 and Type 2. Cured participants with a history of hepatitis C infection who have a negative PCR test at screening are eligible.

-has a documented diagnosis of a form of primary immunodeficiency (PID)