The influenza virus has caused epidemics every 1-3 years during the past 400 years, including four major pandemics. This year is actually the 100th anniversary of the 1918 pandemic, which affected a third of the global population and killed 50 million people.

When it comes to an infection like influenza, your body’s natural defense system works by deploying roaming cells that capture small viral particles and immediately raise alert. This triggers your immune system to start generating antibodies and the ‘symptoms’ you feel are the result of your body killing off your own infected cells. The discovery of vaccines was one of the biggest medical breakthroughs in history—with the idea that you could ‘train’ your immune system to recognize a virus before it begins infecting your human cells and other people.

Many people think the flu isn’t a big deal. But the virus itself is a freak of nature, having shed every single organelle through evolution to be able to hijack our own cells and replicate. While most elderly deaths from influenza happen through complications like pneumonia, when young and healthy people die of the flu, it can involve the stuff of nightmares: blood-hemorrhaging, self-demolition, and drowning in your own lungs.

Vaccines are the best defense we have against infectious diseases. Through them, we’ve eradicated smallpox and nearly eliminated polio. Illnesses like measles, diphtheria, tetanus, and whooping cough are no longer large scale public health crises. But as infectious diseases become less common, we gain the privilege to ask about and better understand vaccine safety, especially on the individual level. With flu season upon us, we’re here to address some of your most common questions about the influenza vaccine.

Does the flu vaccine work?

The flu vaccine isn’t 100% effective (no vaccine is). In fact, it’s likely the least effective vaccine. This is because the influenza virus mutates so often, it can be difficult to target the exact strains that will be the most prevalent. However, that doesn’t mean it’s useless. Flu vaccinations reduce the risk of illness by 40-60% during well-matched seasons—specifically, from 2.3% to 0.9% (REF). That being said, new therapies with superior efficacy and a similar or better safety profile are urgently needed.

Aren’t flu shots just Big Pharma pushing agenda to make money?

Worldwide sales of flu vaccines are around $3 billion. While that may sound like a lot, put it in the perspective of all pharmaceutical products ($1 trillion) and suddenly it’s not much: <0.3%. The real problem is actually the opposite—companies are making so little money from influenza, that there’s very little R+D spending as these initiatives are deprioritized. The most recent flu vaccine cost over $1 billion to get approved, but won’t break even for another 9 years (REF). While officials recognize that better vaccines are needed, current policy has created an environment lacking the political will to develop novel-antigen game-changing vaccines.

I heard flu shots are filled with heavy metals and poisonous ingredients.

Most are worried about ‘toxins’ like thimerosal (REF) and formaldehyde. Your calls for alternatives have already fostered new choices: thimerosal was stripped from all pediatric vaccines in 2001 (REF) and there are numerous thimerosal and preservative-free (and even vegan) options available today, like single dose or nasal sprays.

Formaldehyde is used in very tiny amounts in some vaccines to inactivate the virus so it can’t cause actual disease. Sounds scary, but formaldehyde occurs naturally in many fruits and vegetables like apples, pears, apricots, spinach, onions, and carrots (REF), and is even produced by the human body (and circulates in our bloodstream) for a variety of functions, including producing amino acids.

Can’t I just prevent the flu by living a healthy lifestyle?

This is a great start. A healthy immune system is your body’s best natural defense against pathogens. Your daily choices—diet, exercise, stress, sleep, caring for your microbiome—are all factors that support or subtract from immune health. Some people even have genetic factors that equip them with flu-fighting antibodies. But a healthy immune system is not a failsafe, especially if a strain is especially virulent.

Is herd immunity a reason to get the flu shot?

Your choices extend beyond your body. A healthy immune system may help you ward off the flu or recover from it quickly, but it doesn’t help you not infect others, especially the elderly and immunocompromised in your community. 80,000 Americans died from the flu last year (REF) and they all caught it from someone else. While the flu shot may not have immediate benefits for you, a well-vaccinated community is generally better defended from outbreak. We have no way of knowing when the next pandemic will be, which raises the question: are health decisions we make for our own bodies able to benefit our greater ecosystem?

So, what now?

Immunology is an incredibly complex field—and our understanding of antibodies, T cells, and molecular mimicry grows each year. As science progresses, the future of combating influenza may not even include vaccines. Just last week, breakthrough research was published around non-vaccine therapies that could immediately neutralize influenza virus of all strains (REF). We will continue to track this research and share breakthroughs as they progress into the clinic.