The flu vaccine is more effective than expected, federal health officials said on Thursday at a special news conference held to discuss the dangerous flu season, which is expected to kill more than 50,000 Americans.
This year’s vaccine is about 25 percent effective against the H3N2 strain of flu that is causing most illnesses and deaths, said Dr. Anne Schuchat, acting director of the Centers for Disease Control and Prevention.
In a bigger surprise, the vaccine is about 51 percent effective in children, according to the C.D.C.’s preliminary analysis.
In Australia, the same vaccine was rated about 10 percent effective overall against H3N2, and a recent Canadian analysis found it to be about 17 percent effective there. (The C.D.C.’s final analysis will not be ready until the flu season ends in late spring.)
Dr. Schuchat and Alex M. Azar II, the new secretary of health and human services who led the news conference, also pointed to a C.D.C. study published Monday in the journal Pediatrics showing that two-thirds of the 675 children and teenagers who died of flu between 2010 and 2016 had not gotten the vaccine the year they died.
“Go get a flu shot!” Mr. Azar said loudly as he ended his portion of the news conference. “Do it for yourself, your family and your community!”
He, his wife and his children had all had flu shots, he said, and so had President Trump.
The vaccine is 39 percent effective overall, Mr. Azar said, and 59 percent effective in children. He compared the vaccine to seatbelts.
“Imagine if we could cut our chances of being in a car crash by 39 percent, or our child’s by 59 percent,” he said. The comparison was only partly correct but very apt.
The figures refer to the effectiveness of the vaccine against all circulating strains, including H1N1 and B strains, which have only barely begun to appear this year.
But seatbelts are a telling analogy for flu shots. Studies done since the 1970s have shown them to be only about 40 percent protective against preventing any injury in a crash.
But they are highly protective against death; that is, when crashes are so severe that some occupants are killed while others live, it is almost always the ones not wearing belts who die.
Likewise, studies like the C.D.C.’s suggest that flu shots do a better job of preventing death than preventing sniffles and aches.
Mr. Azar’s news conference, at H.H.S. headquarters, was brief and unusual. It was held midafternoon on only a few hours’ notice. It was televised, but no questions were taken from outside the room.
The event ended with a large panel of experts awaiting questions. Only one was asked: whether administration officials wished they had done anything differently about flu this year.
Dr. Schuchat replied by describing problems that vaccine makers face. She did not address a bigger issue of concern to the C.D.C.: Only about 40 percent of Americans get flu shots each year by the time the season begins in November, and that number has been going down, not up.
The Trump administration and its top health officials have been criticized for showing little public leadership as the flu season became more dangerous. The news conference appeared to be an attempt to remedy that.
Mr. Azar was followed at the podium by Dr. Schuchat and Dr. Jerome Adams, the surgeon general, both in naval uniforms. They were referred to on the podium as “admirals” — which is correct, because they hold ranks in the Public Health Service Commissioned Corps, although the use of their military titles in medical settings is somewhat unusual.
Also on the dais were Dr. Anthony S. Fauci, director of the National Institute for Allergy and Infectious Diseases; Dr. Scott Gottlieb, commissioner of the Food and Drug Administration; and Dr. Robert P. Kadlec, assistant secretary for preparedness and response at H.H.S.
But they had little to say because the session ended abruptly.