With the arrival of fall, we are quickly approaching the season of cooler temperatures, turning leaves, and festive holidays. We are also at the start of flu season and the onslaught of the end of the year bugs and illnesses. During this time of year, many people focus on strengthening their immune system, but what exactly goes into keeping ourselves and the ones around us immune from sickness?

Active Immunity vs Passive Immunity

First, let’s talk about what immunity is. Immunity is generally your body’s ability to resist succumbing to an illness caused by pathogenic (disease-causing) bacteria or viruses.

The body achieves this by creating antibodies to fight off specific illnesses. Antibodies are special proteins that attack toxins or organisms that cause disease, including bacteria and viruses. There are two types of immunity that fall within this type of system: active immunity and passive immunity.1

Passive Immunity

Passive immunity occurs when one receives antibodies from another person immune to a disease instead of having their bodies actively produce antibodies. For example, infants acquire passive immunity through maternal immunoglobulins passed down through the placenta or through breastmilk.2

Passive immunity has the advantage of providing immediate protection against disease, but its protection is short-lived. Passive immunity may last only a few weeks or months. In adults, common vaccines use immunoglobulins to provide immediate protection against disease include the post-exposure vaccines for Hepatitis B, rabies, tetanus, and chicken pox.3 This is a manufactured way of acquiring passive immunity.

Active Immunity

Active immunity is exactly what it sounds like – it occurs when your body is exposed to a disease-causing bacteria or virus and your body produces antibodies to fight and protect against disease. Active immunity can be split into two categories – natural immunity or vaccine-induced immunity.

Natural immunity occurs when you naturally encounter an organism and your body produces antibodies to fight it off. Vaccine-induced immunity occurs when a dose of a killed/weakened organism or toxin is administered and your body produces antibodies against the introduced vaccination. Common vaccinations to provide active immunity include those for diphtheria, pertussis, tetanus, and hepatitis A. Active immunity may take a little longer to form, but may provide life-long protection against certain diseases.4

Innate vs. Adaptive Immunity

Now that we know about how we become immune to pathogens, let’s talk more about what happens during an immune response.

When your immune system is triggered, there are two systems of immunity that are activated – first the innate immune system followed by the adaptive immune system.

Your innate immune system acts as a general response to any invading bacteria or virus attempting to cause illness. It is composed of several systems including physical barriers, such as the skin, respiratory tract and gastrointestinal tract, chemical responses, and cellular components, including cells that identify, surround, and kill pathogens.5

Once the innate immune system is activated, the adaptive immune system activates to respond to specific pathogens by creating antibodies. The antibodies attach to pathogens and make it easier for other cells (like T cells or natural killer cells) to get rid of the disease.

Adaptive immunity is unique in that the immune response is “remembered” for each disease encountered. In other words, if the same disease is encountered a second time, the adaptive immune response can be faster and help you recover in a shorter period of time.6

In order to support your immune system to work at its best, lifestyle behaviors like proper sleep, physical activity, handwashing, and sunlight exposure (for extra vitamin D) can be helpful. Diet is an important component of maintaining immune health as well – a balanced diet containing fruits and vegetables which provide vitamins and minerals for enzyme function and antioxidants can make a huge difference in how your body responds to illness.

For an extra boost to your immune system, IVL’s All Day Energy Greens contains a blend of 27 nutrient-dense ingredients that provide essential vitamins and minerals, antioxidants, phytonutrients, probiotics and prebiotics. All Day Energy Greens can help naturally support your immune system during cold and flu season.

Yours in Health-

Ana Reisdorf, MS, RD
IVL’s Community Registered Dietitian


  1. Immune Response. MedlinePlus. U.S. National Library of Medicine. Updated Sept 11, 2019. Retrieved from: https://medlineplus.gov/ency/article/000821.htm
  2. Verhasselt V. Is infant immunization by breastfeeding possible? Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 2015 Jun; 370(1671). https://www.ncbi.nlm.nih.gov/pubmed/25964452
  3. Vaccines & Immunizations: Immunity Types. Centers for Disease Control and Prevention. Updated Mar 20, 2017. Retrieved from: https://www.cdc.gov/vaccines/vac-gen/immunity-types.htm
  4. Baxter D. Active and passive immunity, vaccine types, excipients and licensing. Occupational Medicine. 2007 Dec; 57 (8): 552-6. https://www.ncbi.nlm.nih.gov/pubmed/18045976
  5. Hato T & Dagher PC. How the innate immune system senses trouble and causes trouble. Clinical Journal of American Society of Nephrology. Aug 2015; 10(8) 1459-1469. DOI: https://doi.org/10.2215/CJN.04680514
  6. Features of an Immune Response. National Institutes of Health National Institute of Allergy and Infectious Diseases. Updated Jan 16, 2015. Retrieved from: https://www.niaid.nih.gov/research/immune-response-features