Trending Now - US Officials Report Low Effectiveness of Flu Vaccines

WHO:

Dr. William Schaffner, Vanderbilt University vaccine expert

Centers for Disease Control and Prevention (CDC)

World Health Organization (WHO)

U.S. Food and Drug Administration (FDA)

WHAT:

The flu vaccine was around 25% to 30% effective in preventing adults from needing medical treatment due to flu.

Children who were vaccinated were about 40% less likely to seek treatment at a doctor’s office or hospital.

CDC estimates indicate at least 27 million illnesses, 350,000 hospitalizations, and 22,000 deaths from flu this season.

At least 101 children have died from flu this season, with about 85% of those known to be unvaccinated.

Adult vaccination rates increased to 46.5% this season.

An estimated 48% of U.S. children were vaccinated against flu by the end of February 2026.

The WHO recommended vaccines for the 2026-27 northern hemisphere flu season to address subclade K.

WHERE:

United States

New York City

WHEN:

The flu season is winding down in March 2026.

CDC data was posted on March 10th, 2026.

The flu infections surged in late December 2025.

The Trump administration stopped broadly recommending flu shots for all children in January 2026.

WHY:

A new strain of flu virus, A H3N2 subclade K, was not well matched to the vaccine, leading to low effectiveness.

Relatively low flu vaccination rates contributed to the flu's spread.

HOW:

The vaccine available this season was designed to address a different version of H3N2.

(UPDATED March 13, 2026 23:12 UTC)

The Centers for Disease Control and Prevention reported that the flu vaccine this season was only about 25% to 30% effective in preventing adults from needing medical treatment, while vaccinated children were roughly 40% less likely to seek care. With at least 27 million illnesses and 350,000 hospitalizations attributed to the flu this season in the U.S., the World Health Organization has recommended vaccines for the upcoming 2026-27 northern hemisphere flu season to better address the subclade K strain. Tragically, at least 101 children have died from the flu this season, with around 85% of those being unvaccinated, highlighting the importance of vaccination as adult rates reached 46.5% and approximately 48% of children were vaccinated by the end of February.