Originally posted here by co-authors Rachel Cunningham, MPH, Immunization Project at Texas Children’s Hospital and Carlie Machir, patient at Texas Children’s Hospital

As a mother of two, one of the lessons I’ve strived to teach my children is to think about others, not just themselves. How many of you have heard yourself say, “It’s not just about you!”? If you’re anything like me, you hear it quite a bit. Whether I’m taking my youngest daughter shopping for new shoes while her older sister complains, or trying to explain to them we can’t go to the playground today because we’re making dinner for a friend with a new baby. I’m constantly trying to teach my children to grasp the bigger picture – that life is not always about you. This common parenting sentiment holds true for many things including vaccine-preventable diseases. With that in mind, and as we start the school year, we’re preparing for influenza season and this lesson remains as important as ever.

One of the most critical – and easily forgotten – aspects of vaccination, is the protection it offers not just each individual but the community at large, in particular those who are unable to be vaccinated themselves. These individuals may be too young to be fully immunized or they may have a medical condition that makes them ineligible for vaccination. Some individuals may also be more vulnerable to the devastating effects of vaccine-preventable diseases, particularly influenza. This includes individuals with severe allergies to the flu vaccine and individuals with a compromised immune system (such as cancer patients). These individuals must rely on the people around them, within their families and communities, to get vaccinated and protect them from the flu. This concept is known as community immunity or herd immunity.

But what is community immunity? What does it mean in practical terms? What does protecting those who can’t protect themselves look like?

Let me introduce you to my friend, Carlie. A mother of two, Carlie is pictured here holding her younger daughter, Mia.

When Carlie was 27 weeks pregnant with Mia, doctors found a grapefruit sized mass in her chest which turned out to be non-Hodgkin lymphoma. After two rounds of chemotherapy, Mia arrived at 31 weeks on Sept. 3, 2015. While Mia was in the neonatal intensive care unit (NICU) at Texas Children’s Hospital, Carlie continued her treatment including four more rounds of chemotherapy and 17 sessions of radiation. Throughout this time, Carlie and Mia were incredibly vulnerable to any illness. As it was also the heart of flu season, vaccines were suddenly never more important to their well-being, leaving Carlie and Mia to rely on the protection of those around them. Here’s Carlie describing her experience with cancer and the importance of community immunity in her own words.

“I have always been more inclined to live a more natural, crunchy lifestyle. I was never quick to use medicine on myself or my first baby. When I was diagnosed with cancer and had Mia early, vaccines suddenly became really critical as it was the start of flu season. Knowing any virus, particularly the flu, could be deadly to me and my daughter and that most people don’t get the flu vaccine, we were forced to stay home most of the time and limit contact with others. It simply wasn’t worth the risk. My immune system was so weak that while a healthy adult will have a white blood cell count between 5,000-10,000, my white blood cell count was in the hundreds at its lowest point. Not only was I incredibly vulnerable to any illness, my doctors had to delay my treatment until my white blood cell count improved. We stopped going to church and others brought us food and groceries. I had to ask everyone who visited and brought food over to get the flu vaccine. I never imagined myself requesting this of people, but I had no choice. We needed the protection of others around us to keep us healthy. And honestly, as I was going through chemotherapy and radiation and watching my premature baby learn to breathe and eat, all of the reasons to not get the flu vaccine became quite trivial. It is free, or nearly free, available everywhere and the flu is a life-threatening condition when your immunity is non-existent. One year later, I’m in remission and my daughter is healthy and developing normally. Even so, my family will continue to get our flu shots so we can protect others who are unable to protect themselves. After all, there are always people who need it just like we did.”

I hope this paints a picture of the impact your decision to vaccinate has on those around you, whether it’s a loved one fighting cancer or your best friend’s new baby who is too young to receive her flu shot. Flu season is just around the corner and each year it affects hundreds of thousands of individuals. While flu is especially dangerous to the medically vulnerable, it is dangerous to healthy people also. The influenza virus can affect anyone – rich, poor, young and old. It cannot be prevented through exercise, rest and healthy eating, even though those are all good things. Getting vaccinated against the flu is single-handedly the best way to protect yourself and your loved ones. By choosing to vaccinate, you are choosing to help protect the vulnerable members in your family, your circle of friends and your community. At the end of the day, their well-being depends on it.