More than 80,000 Americans died of the flu in the winter of 2017-2018, the highest number in over a decade, federal health officials said last week.
Although 90 percent of those deaths were in people over age 65, the flu also killed 180 young children and teenagers, more than in any other year since the Centers for Disease Control and Prevention began using its current surveillance methods.
The estimates were released at a news conference held by the National Foundation for Infectious Diseases to urge Americans to get vaccinated and to fight the myths that scare off some people — such as the common misconception that flu shots can cause flu.
The high mortality rate was unusual because it was caused by a “normal” — albeit severe — flu season, not by a new pandemic influenza strain.
In the 2009-2010 swine flu epidemic, by contrast, 59 million Americans are thought to have caught the novel strain that first appeared in the spring, but only about 12,000 died because the infection was relatively mild, according to the C.D.C.
(That flu, an H1N1 strain, was called a “swine flu,” despite the objections of the pork industry, because it emerged in a pig-farming region of Mexico and was the first human flu virus to contain genes from both North American and Eurasian pig flus.)
The dominant strain last season was an H3N2 flu, which is usually the most deadly of the four seasonal flu strains that typically circulate.
Last season’s flu vaccine was only about 40 percent effective at preventing infection — approximately the same as the previous season’s, according to the C.D.C.
Vaccine effectiveness varies quite a bit each year, from a high of 60 percent in 2010-11 to a low of 19 percent in 2014-2015.
It is impossible to know yet how effective this year’s vaccine will be.
Infectious disease specialists have long expressed frustration that medical science has not come up with a universal lifetime flu vaccine. Currently available vaccines target the spikes on the virus’s outer shell, which are the parts that mutate the fastest.
Because it takes more than six months to make each year’s vaccine, manufacturers have to choose in February what strains to put into shots that will be shipped in September. During that interim, circulating flus can mutate to become a partial mismatch to whatever was chosen.
But experts still urge people to get even imperfect shots, because while they may be only 40 percent effective at warding off body aches and runny noses, they are much more effective at preventing influenza’s worst outcome — death.
Donald G. McNeil Jr. is a science reporter covering epidemics and diseases of the world’s poor. He joined The Times in 1976, and has reported from 60 countries.