Secondary Immunodeficiency (SID)

Some people with blood cancers (hematologic malignancies) develop a weakened immune system because of their condition or the medicines used to treat it. This is called a secondary immunodeficiency or SID. A weakened immune system can make it harder for the body to fight infections. SIDs make participants more likely to have serious infections, need treatment at a hospital, and need longer treatment periods with antibiotics. SIDs are common but often overlooked in people with blood cancers in Kazakhstan. Currently, Kazakhstan does not have national guidelines for diagnosing and managing SIDs, which leads to differences in how people are assessed and treated across healthcare settings. The main aim of this study is to understand how common SIDs are in adults with blood cancers in Kazakhstan, which people are most affected and how often related health problems such as infections happen. Other aims are to learn more about SIDs in Kazakhstan: how SIDs are treated, how they affect a person's health and daily life (clinical burden) and how certain factors (such as age, health condition, treatment, type and stage of the blood cancer) may influence SIDs. This study will not collect any new data. It will use existing health records and data from Kazakhstan's national oncology registry.

In this study, multiple myeloma participants with secondary immunodeficiency (SID) will be treated with HyQvia according to their clinic's standard practice. The study's main aim is to look into infusion parameters of HyQvia administration.

The goal of this observational study is to improve the treatment of hematological patients with secondary immunodeficiency (SID) by developing a patient-reported outcome (PRO) instrument to detect clinically diagnosed infections. The study focuses on adults diagnosed with chronic lymphocytic leukemia (CLL) or multiple myeloma (MM) who are at increased risk of infections due to SID. The main questions it aims to answer are: 1. Can a newly developed PRO screening tool for infection-related symptoms reliably detect infections in patients with SID? 2. How does the health-related quality of life change over the treatment course Participants will: * Complete daily electronic PRO questionnaires (ePRO) to monitor infection-related symptoms * Complete ePRO health-related quality of life questionnaires every 1.5 months * Participate in study visits every three months to ensure documentation of clinical data