The CDC estimates that every year, between nine and 36 million will get the flu each year in the US; 12,000 to 56,000 will die from it, and 140,000 to 710,000 will be hospitalized because of it. And yet every year, people consider whether or not to get a flu shot, if getting vaccinated is worth the potential risk. However, the more you know about how the virus and vaccine work, the more obvious it becomes that getting vaccinated is almost always the right decision.

There is a common misconception that the flu shot will give you the flu, a lie which the Harvard Health Blog shut down in a November 2014 post. In fact, according to the Center for Disease Control and Prevention (CDC), which conducts studies every year to determine how well the vaccine protects against the flu, the vaccination reduces the risk of illness by between 40 and 60 percent. More specifically, flu vaccines tend to work better at preventing influenza B and influenza A (H1N1) than influenza A (H3N2), as the latter has more frequently resulted in antigenic changes (mutations) than the other two.

Two factors play an important role in determining how effective a flu vaccine will be. First, the characteristics of the person being vaccinated, particularly age and general health. And second, the similarity of the flu virus to the vaccine designed. If the flu vaccine is not well matched to the circulating virus, it is possible that there will be no benefit from vaccinating. So, scientists specifically match the vaccine given to the most popular strain of the virus currently circulating. In January 2018, the New York Times published an article describing how scientists match the flu vaccine each year to that of Australia’s, whose flu season is before ours.

Besides preventing you from getting the flu, the vaccination has many other benefits. The CDC explains that the vaccine can be beneficial to people with chronic health conditions, specifically by lowering the rates of cardiac events and reducing hospitalizations among people with diabetes and chronic lung disease. It also helps protect women during and after pregnancy, and helps protect the baby from getting the flu after birth (as the mother passes antibodies onto the fetus during pregnancy.) The vaccine can also reduce a child’s risk of death from influenza, making the illness milder, reducing the risk of it developing into pneumonia, and protecting the people who are more susceptible: young children, pregnant women, older adults, and people with chronic health conditions like heart disease, asthma and diabetes.