A new study finds that flu shots were associated with moderate protection against the virus during the 2024-25 flu season.

People vaccinated against influenza that season were 40% less likely to test positive for flu than unvaccinated people, according to a study of more than 1.1 million Californians.

Adults aged 65 and older who tested positive for flu were 29% less likely to die of an influenza-related cause if they had received the vaccine, according to the study, published yesterday in JAMA Network Open. The study included flu-related deaths within 30 days of testing.

“These findings are consistent with protection against severe and fatal influenza among people vaccinated against influenza,” the study authors wrote.

A ‘high severity’ flu season

The analysis comes from a case-control study of people aged 6 months or older who were tested for influenza from October 1, 2024 to May 31, 2025, which was considered a “high severity” flu season, with the highest rate of influenza-associated hospitalizations in 24 years.

Flu caused an estimated 610,000 to 1.3 million hospitalizations that season, along with 27,000 to 130,000 deaths, according to the study, led by the California Department of Public Health.

The flu killed 289 children that year, surpassing the previous record set during the 2009 to 2010 season, which was marked by the H1N1 flu epidemic.

Public health experts recommend annual flu shots to reduce the risk of illness, hospitalization, and death.

When Michigan State University researchers anonymously surveyed Centers for Disease Control and Prevention (CDC) staffers, 99% of respondents said that federal policy changes, dramatic reductions in staff and programs, and unstable or leadership have hobbled the agency’s ability to respond to a pandemic or other public health emergency—and 95% think Americans will die as a result.

In total, 624 workers (433 still in their positions, 191 who quit) responded to the survey from February to April. 

“Since the second Trump Administration took over leadership of the U.S. federal government on January 20, 2025, the Centers for Disease Control and Prevention (CDC) has undergone significant changes and challenges, including lack of permanent leadership, elimination of programs, reductions-in-force and loss of staff, a deadly shooting, new policies, and restrictions on hiring, communication, and spending,” the authors wrote.

96% doubt that CDC can remain global leader

Of all respondents, 95% of those who quit said they did so entirely or mostly because of federal changes, and 68% of current workers have taken action to leave (eg, applied for another job).

The difficulties described by CDC workers portend a U.S. government losing its ability to protect the public’s health.

In total, 94% said their unit has been so weakened that it can no longer achieve its mission, and 96% doubt that the CDC can remain a global public health leader.

In an open-ended answer, a CDC scientist wrote,” The safety and health of the U.S. population will suffer, but it will be hard to quantify because they have compromised our ability to collect the data to demonstrate the impact of what they have done.”

A former manager said, “The anti-vaccine, anti-science stance of this Administration meant that I could no longer in good conscience continue to work there given the type of work that I did.”

The researchers concluded, “The difficulties described by CDC workers portend a U.S. government losing its ability to protect the public’s health.”

• The US Department of Agriculture Animal and Plant Health Inspection Service noted three new H5N1 outbreaks in commercial poultry facilities and backyard flocks this past week. Twenty birds in Canyon County, Idaho, were affected. In Elkhart County, Indiana, which has been a hotbed of avian flu activity, a poultry facility reported an outbreak involving 19,200 birds. Finally, in Passaic County, New Jersey, a live bird market saw an outbreak involving 670 birds. In the past 30 days, avian flu has been confirmed in 22 flocks, with 240,000 birds affected.
• Florida is reporting an early jump in cases of Vibrio vulnificus, or flesh-eating bacteria. So far this year eight cases have been reported, double what was reported this time last year. The naturally occurring bacteria is found in warm marine water. Most people infected are exposed through eating undercooked seafood, but more serious infections occur when the bacteria enter the bloodstream through open wounds. Serious infections are more common in those with weakened immune systems. Among the eight cases this year is a 17-year-old boy who was hospitalized after he went swimming with a scrape on his leg.
• The Food and Drug Administration says 62 people have been sickened in a new Salmonella Enteritidis outbreak, but a source has not yet been identified. Patient ages and states where patients live have also not been published, according to Food Safety News.