This study will investigate the function of the immune system in people with chronic kidney disease (CKD) compared to people with normal kidneys. The investigators will use standard vaccines - the seasonal flu vaccine and pneumococcal polysaccharide (Pneumovax) vaccine - to examine how the immune system responds to challenge. All subjects will receive these recommended vaccines as part of routine care. Blood and urine samples will be collected and tested at different time points to look at how the immune response develops to these vaccines and if there are any differences between people with CKD and those without. This will help us understand how CKD affects the function of the immune system.

Compared to the general population, people with CKD are known to get more infections and are more likely to have complications from them. Protective measures such as vaccinations for common infections are not as effective in patients with CKD as they are in people with healthy kidneys. The reasons why this happens are not very clear. It is known that with increasing age, the body's immune defences are weakened, but it is not yet clear how different this is in older people with CKD compared to older people with healthy kidneys. Understanding how CKD affects the body's immune defence to new infections is vital in helping to prevent severe consequences from infection and make vaccination more effective for this group of people. This project aims to look at the function of immune cells in CKD patients and people with normal kidney function, together with their responses to clinically recommended vaccinations, including Pneumococcus (common pneumonia organism) and the influenza virus (the flu).

Study participants are invited to receive the clinically recommended seasonal influenza and pneumococcal polysaccharide vaccines during the seasonal influenza vaccination season (September - December), mirroring routine care they would receive in the community. Information on age, gender and pre-existing health problems, together with blood and urine samples will be collected from CKD patients for comparison with healthy volunteers at the following timepoints: day of vaccination, day 7 and 28 and 6 months after vaccination.

Inclusion Criteria:

• any gender
• aged 65 and over

Exclusion Criteria:

• Subjects who have had Pneumovax within last 5 years
• Subjects who have had current season's influenza vaccine
• CKD patients: eGFR less than 15ml/min or greater than 60ml/min, immune mediated cause of kidney disease.
• Healthy control subjects: known kidney disease, eGFR less than 60ml/min
• Subjects with comorbidities that are associated with an immunosuppressed state including, but not limited to, the following: Malignancy diagnosed within last 5 years except non-melanoma skin cancer; Solid organ (including kidney) or bone marrow transplant recipients; Blood borne viral infections: HIV, hepatitis B and C; Autoimmune disease e.g. vasculitis, rheumatoid arthritis; Previous splenectomy or asplenia from any other cause.
• Subjects currently taking any of the following immunosuppressive medications: Systemic corticosteroids e.g. prednisolone/dexamethasone; Chemotherapy agents e.g. cyclophosphamide, methotrexate, azathioprine; Biological therapies e.g. rituximab, infliximab, etanercept - including any administration within preceding 12 months.
• Subjects who have previously had a serious reaction to influenza vaccination, including anaphylaxis and Guillain-Barre Syndrome within 6 weeks of previous influenza vaccination
• Subjects who have a severe egg allergy (contraindication to influenza vaccination)
• Subjects who have previously had a serious reaction to the whole or any components of pneumococcal vaccination
• Subjects who have an active infection and/or are febrile on assessment

CKD patients - individuals attending local tertiary care nephrology clinics.

Healthy control subjects - individuals accompanying CKD patients to nephrology clinics or individuals invited to participate from Birmingham 1000 Elders Cohort.