Longevity and Immunity: Preparing Your Defences for Winter

Why immunity is a longevity issue this winter

As the days shorten, influenza, RSV and COVID-19 begin to circulate together, and the European Centre for Disease Prevention and Control has already urged Europeans to prepare before the winter peak [2]. For many people a winter virus means a week in bed; for others it means weeks of lingering fatigue, a cough that will not settle, or a serious complication. The difference often lies in how well the immune system has aged. With time, the immune system loses some of its precision (immunosenescence) while developing a chronic, sterile, low-grade inflammation known as "inflammaging", which researchers now link to most age-related diseases, from type 2 diabetes to cardiovascular disease [1]

Protecting and restoring immune function is therefore not a seasonal luxury: fewer infections, faster recovery and a lower inflammatory burden are core goals of longevity medicine.

What a longevity clinic can measure

Immunity cannot be captured by a single number, but a structured assessment can reveal where your defences are weak. A post-infection and immune-resilience assessment starts with a detailed infection history and validated fatigue and sleep questionnaires. It then moves to a one-day diagnostic panel. This includes a full blood count with differential (lymphocyte and neutrophil counts), inflammatory markers (hs-CRP, ESR) and immunoglobulins (IgG, IgA, IgM). It also covers immune- relevant nutrients (vitamin D, zinc, ferritin, B12, folate), glucose control (HbA1c, HOMA-IR), thyroid function and morning cortisol. Functional measures should follow in a personalized and customized manner and could include body composition (InBody), VO2max, heart-rate variability, Detox scan. This information combined will show in what extent the body is exposed to inflammaging and how well it is coping and recovering from it. Futhermore after an infection, an ECG and, where symptoms suggest it, cardiac and lung testing exclude complications. For people with recurrent, severe or unusual infections, a second-line panel (lymphocyte subsets, vaccine antibody responses, complement) can identify a true immune deficiency that needs specialist care.

The foundations: sleep, movement, food and vaccination

The strongest evidence for immune resilience is not found in a pill. In a study in which healthy adults were deliberately exposed to a cold virus, those who slept less than six hours a night were 4.2 times more likely to develop a cold than those who slept more than seven [3]. Regular movement matters just as much: among 1,002 adults followed through autumn and winter, those doing aerobic exercise on 5 or more days a week had 43% fewer days with upper respiratory infections than largely sedentary adults [4]. A protein-adequate Mediterranean diet rich in vegetables, fibre and fermented foods, limited alcohol, and good control of blood sugar complete the picture. Finally, vaccination remains the most effective protection against severe illness. Influenza and COVID-19 vaccines are recommended for older adults and people with chronic conditions, and RSV and pneumococcal vaccines are available for older adults too. These go alongside simple measures such as hand hygiene, ventilation and staying home when unwell [2].

Supplements: what the evidence actually supports

Supplements work best when they correct a measured need, which is why we test before we prescribe.

• Vitamin D. A large 2017 analysis found daily or weekly vitamin D modestly reduced respiratory infections, with the clearest benefit in people who were deficient [5]. A 2025 update of 40 trials found a smaller effect that was no longer statistically significant [6]. The sensible approach is to check your level and correct a deficiency, not to take high doses blindly.
• Zinc. Taken preventively, zinc has little or no effect. Started at the first symptoms, it may shorten a cold by about two days, although altered taste and nausea are common [7].
• Vitamin C. Regular vitamin C does not reduce how often most people catch colds, but it shortens them slightly (about 8% in adults). In people under heavy physical stress, such as marathon runners, it roughly halved the risk [8].
• Probiotics. These may lower the chance of an upper respiratory infection and reduce antibiotic use, but the certainty of the evidence is low [9].

"Immune boosting" should mean restoring normal function, not stimulating the immune system beyond it. Products such as echinacea are therefore avoided in autoimmune disease or during immunosuppressive treatment. IV therapies could be considered only selectively, under medical supervision and according to country legislation.

Your personal winter plan

Longevity medicine has a goal and this is to turn your results into a personalised plan: correcting deficiencies, improving sleep and fitness, reviewing your vaccinations and, after an infection, guiding a structured recovery so you return to full energy safely. This is especially worthwhile if you catch infections frequently, feel you never fully recovered from a previous virus, are over 50, or live with a chronic condition. Some symptoms need prompt medical attention and we should be clear about it: persistent high fever, breathlessness, chest pain, confusion, or an illness that worsens after initially improving, so that acute illness is controlled in a hospital environment before a longevity plan could be considered. Book your immune-resilience assessment and enter this winter prepared.

Sources

1. Franceschi C, Garagnani P, Parini P, Giuliani C, Santoro A. Inflammaging: a new immune–metabolic viewpoint for age-related diseases. Nature Reviews Endocrinology. 2018;14(10):576–590.

2. European Centre for Disease Prevention and Control. Respiratory infections season. 22 October 2026.

3. Prather AA, Janicki-Deverts D, Hall MH, Cohen S. Behaviorally assessed sleep and susceptibility to the common cold. Sleep. 2015;38(9):1353–1359.

4. Nieman DC, Henson DA, Austin MD, Sha W. Upper respiratory tract infection is reduced in physically fit and active adults. British Journal of Sports Medicine. 2011;45(12):987–992.

5. Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583.

6. Jolliffe DA, Camargo CA, Sluyter JD, et al. Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data. Lancet Diabetes & Endocrinology. 2025;13(4):307–320.

7. Nault D, et al. Zinc for prevention and treatment of the common cold. Cochrane Database of Systematic Reviews. 2024. CD014914.

8. Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2013;(1):CD000980.

9. Zhao Y, Dong BR, Hao Q. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database of Systematic Reviews. 2022. CD006895.

Reviewed by Dr. Erietta Galani, MD, PhD in cellular immunology, dual specialty in internal medicine and intensive care, Founder and Medical Lead, minus10med, Athens.
Professional identification number: 2995
Last reviewed: 6 November 2026

This article is for general information and does not replace an individual medical consultation.