Flu

Severe flu infections can lead to a range of deadly complications, especially in people whose immune systems are compromised by age or disease.

Many factors affect the infectious period of seasonal influenza, commonly called "the flu," but there are some good rules of thumb for when it's safe to return to work or school.

Data from the Southern Hemisphere hint that this year's flu shot lowers the risk of hospitalization among vulnerable demographics.

Unlike past flu shots, flu vaccines for the 2024-2025 season don't contain the "Yamagata lineage" of influenza viruses because evidence suggests that type of flu no longer exists.

The latest human case of bird flu in the U.S. occurred in a patient with no reported exposure to affected animals, sparking questions over whether the virus is spreading between people. Experts say that's unlikely but argue the case raises other concerns.

People could previously get the nasal spray flu vaccine, called FluMist, from a health care provider, but now they can administer it themselves.

Flu viruses that can use a second cellular entry point may move more effectively between animals and humans, scientists say.

Bird flu in cows and goats has raised alarm in the U.S. To date, four people are thought to have caught the virus from cattle, but the risk to the general public is low.

A fourth person in the U.S. has caught bird flu after working with infected cows on a farm.

Scientists found that contaminated milking equipment can harbor the H5N1 virus for more than an hour, increasing the risk of dairy farmers getting infected.