The 2017 to 2018 flu season in the U.S. was the worst in at least four decades, with around 80,000 deaths and 900,000 hospitalizations, according to the Centers for Disease Control and Prevention (CDC). Those figures include a record-breaking number of deaths in children.
Some of the lethality of last season's flu can be attributed to a particularly bad strain of the virus, called H3N2, which was especially devastating in older adults, Dr. Daniel Jernigan, the director of the CDC Influenza Division, said during a news conference today (Sept. 27). Indeed, 90 percent of the deaths and 70 percent of those hospitalizations attributed to that strain were among people over the age of 65. [Flu Shot Facts & Side Effects (Updated for 2018-2019)]
But last season's flu strain wasn't the only reason for the high numbers of deaths and hospitalizations. Another factor was low vaccination rates, which not only remained far below what they should have been but also slightly decreased last season. According to the National Foundation for Infectious Diseases (NFID), 57.9 percent of people in the U.S. received their flu shot last season, down from 59 percent the season before.
Among the 180 children who died from the flu last season, 8 in 10 weren't vaccinated, Dr. Wendy Sue Swanson, the chief of Digital Innovation and Digital Health at Seattle Children's Hospital, said at the conference.
The CDC recommends that everyone 6 months and older be vaccinated against the flu. Though the vaccine doesn't provide perfect protection from the flu, "give [it] credit for softening the blow," Dr. William Schaffner, the medical director of the NFID, said during the briefing.
Getting the flu vaccine will at the very least give some protection against the flu and could also make the difference between a severe illness resulting in hospitalization and a mild one, Schaffner said.
Schaffner emphasized that the effects of the flu aren't over once the disease ends. Acute influenza initiates a "whole-body inflammatory reaction." Inflammation can affect blood vessels to the heart and the brain and increase the risk of heart attack and stroke in the two to four weeks following recovery from the disease, he said.
Children, older adults, pregnant women and those with chronic health conditions such as heart disease, lung disease, diabetes and obesity are especially at risk of complications from the flu. Especially for older, more frail people, catching the flu can "knock down that first domino of progressive decline," such that a person can't fully bounce back to preflu functionality, Schaffner said.
The CDC is also recommending that those with certain health conditions and adults 65 and older receive vaccinations against pneumococcal diseases that can result from the flu.
But even those who think they're "young and invincible" can be hard-hit by the flu, Schaffner said.
Though children between 6 months and 4 years remain the most highly vaccinated groups, with 67.8 percent being vaccinated last season, the number dropped from 70.1 percent from the season before. Teens between ages 13 to 17 had the lowest rates of vaccination last season, at 47.4 percent, the CDC said.
But everyone, no matter their age, has a "social responsibility" to get the vaccination so as not to contribute to spreading the virus, he added.
Originally published on Live Science.
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Yasemin is a staff writer at Live Science, covering health, neuroscience and biology. Her work has appeared in Scientific American, Science and the San Jose Mercury News. She has a bachelor's degree in biomedical engineering from the University of Connecticut and a graduate certificate in science communication from the University of California, Santa Cruz.