Do you get the flu shot? If you didn’t last year, you and others who declined receiving the annual flu vaccine as recommended by the Centers for Disease Control and Prevention (CDC) could have contributed to one the deadliest flu seasons in decades.

Last season, there was a significant drop of 6.2 percent of American adults who were vaccinated against the flu. Only 37.1 percent of American adults received the shot, lower than the previous seven seasons.

The CDC estimates influenza killed more than 79,000 Americans during the 2017-18 flu season, hospitalized 959,000, and infected 48.8 million.

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Ninety percent of deaths and 70 percent of hospitalizations occurred in people ages 65 and older. But even younger adults were affected. “An estimated 10,300 deaths occurred among working age adults (aged 18–64 years), an age group that often has low influenza vaccination,” the CDC reported.

The CDC estimates 80 percent of child deaths occurred among unvaccinated children. Health officials also reported 183 flu-related deaths among children, although the CDC estimates the actual number of deaths was more than 600.

Several groups have a higher risk for flu-related complications: children under 5, adults over 65, pregnant women, and American Indians and Alaska Natives.

Chronic medical conditions also put people at risk, including lung disease, heart disease, diabetes, and weakened immune systems. Millions of people have these conditions, including an estimated 2.7 percent of adults with compromised immune systems due to HIV, treatment for autoimmune diseases, and using immune-suppressing medications after organ transplant.

Flu-related deaths already being reported this year, so health officials are reminding people that the flu vaccine remains the best protection.

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And it’s not a precaution just for yourself, but for those around you who have higher risk for flu-related complications.

Nicole Basta, assistant professor in the school of public health at the University of Minnesota, says that higher vaccination rates protect both people getting the flu shot and those around them.

“When we each get vaccinated, we boost our own immunity and reduce our own risk of getting the flu,” Basta said. “But just as importantly, we reduce the risk to our families, friends, and our communities by blocking the spread of the flu.”