Feature Article: DYK Trivia? “Love Your Immune System” Edition
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Feature Article: DYK Trivia? “Love Your Immune System” Edition
February 12, 2026

February is the month of love, so what better time to spread a little love with a fun trivia game? We hope you’ll enjoy answering these trivia questions about the immune system — this 24/7 operation that protects us even when we are not thinking about it!

Questions

Scroll down for answers.

Q1. When can immune system cells first be detected during pregnancy?

  1. Around 4 weeks when the fetus is the size of a poppy seed
  2. Around 12 weeks when the fetus is the size of a lime
  3. Around 20 weeks when the fetus is the size of a banana
  4. Around 24 weeks when the fetus is the size of a cantaloupe

Q2. The immune system can be thought of as a police force; the former protects our bodies, and the latter, our communities. With that in mind, match the parts of the immune system to their symbolic equivalent in the police force using the lists below.

Immune system:Police force equivalent:
  1. Bone marrow
  2. Lymph nodes
  3. Innate immune system
  4. Adaptive immune system
  5. Antigen presentation
  6. T cells
  7. B cells
  8. Antibodies
  9. Memory cells
  1. Cops patrolling the local beat
  2. “All-hands-on-deck” alert
  3. Police academy
  4. Troops of officers
  5. Police stations
  6. Police chiefs and sergeants
  7. More experienced officers
  8. Special forces
  9. Weapons carried by officers

Bonus question: If we stick with the police force example, what role would vaccines serve?

Q3. Which of these is NOT an example of passive immunity?

  1. Maternal antibodies present at birth
  2. Immunologic memory
  3. Antibodies in breast milk
  4. Immunoglobulin treatments

Q4. What benefits does memory immunity offer over primary immunity?

  1. The immune response develops more quickly.
  2. The immune response is stronger.
  3. The immune response is more specific.
  4. All of these
  5. Both A and B
  6. Both B and C

Q5. Which of the following is NOT associated with development of autoimmunity?

  1. Inherited genetic variations
  2. Genetic rearrangement of lymphocytes during B and T cell development
  3. Immune tolerance
  4. Spontaneous genetic variations during fetal development
  5. Environmental triggers

Q6. An antigen is the part of the vaccine to which the immune system responds. Which infants received the most antigens from vaccines?

  1. Children born in 1900
  2. Children born in 1960
  3. Children born in 1980
  4. Children born in 2000
  5. Children born in 2025

Answers

A1. The answer is A. Early immune system cells can be identified at 4 weeks, often before a pregnancy has even been realized. Functional T cells can be found by 12-16 weeks, and quantities of macrophages are increasing rapidly by 16-20 weeks. Take a deeper dive into the development of the immune system.

A2. Answers: A=3, B=5, C=1; D=8, E=2, F=6, G=4, H=9, and I=7. Check out more details about each of these comparisons and find out about other parts of the immune system on our “Parts of the Immune System” webpage. 

Bonus question answer: Vaccines are like the practice drills that officers participate in to ensure they are ready for an emergency event.

A3. The answer is B. Immunologic memory is made by the individual’s own immune system, so it is long-lasting. In contrast, antibodies from other sources, such as placental transfer, breast milk, or medical treatments, are short-lived. This is why generating our own immunity through infection or vaccination is better. The benefit of vaccination over infection is that vaccines are tools that allow us to control the time and quantity for exposure to the pathogen to create immunity without the uncertainties that come with wild-type infections resulting from random community exposures. Find out more about active, passive and community (herd) immunity.

A4. The answer is D. Once our immune systems have experience with a particular pathogen, they are better prepared for future encounters, making subsequent immune responses to that pathogen faster, stronger and more specific. Vaccines take advantage of this by introducing our immune systems to potentially severe or deadly pathogens in a way that gives them experience without enduring the risks associated with natural disease. For details on primary and memory immunity as well as discussions of original antigenic sin and considerations related to vitamins, zinc, and other medications and treatments, check the “How the Immune System Works” webpage.

A5. The answer is C. Immune tolerance is something we all rely on so that our immune systems do not attack our bodies. When the immune system does attack some part of our body, that is called autoimmunity, and all of the other answer choices for this question can lead to diseases characterized as autoimmune conditions. Learn more about the different ways the immune system can malfunction.

A6. The answer is B. The smallpox vaccine contained about 200 antigens, and the whole-cell pertussis vaccine contained about 3,000 antigens, so babies born in 1960 received vaccines containing about 3,217 antigens because they got both of those vaccines in addition to a few others. Babies born in 1980 no longer got the smallpox vaccine, but they still got the whole-cell pertussis vaccine among others, so they also received vaccines with more than 3,000 antigens. However, the U.S. switched to using the acellular pertussis vaccine in the early 1990s, so babies born since then have received vaccines containing fewer than 200 antigens. Find out more about this and other concerns related to vaccines and the immune system.

How did you do? We hope you had fun and found new reasons to love your immune system!

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