Older woman coughing
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Up to 1.6 million people were sickened with influenza from Oct 1. through Nov. 11, the Centers for Disease Control and Prevention said Friday.

The agency published preliminary estimates based on data collected through the Influenza Hospitalization Surveillance Network, or FluSurv-NET. The overall range of illnesses during the specified time period was estimated to be 780,000 to 1.6 million.

The flu also resulted in 360,000 to 770,000 medical visits, 8,000 to 17,000 hospitalizations and 490 to 1,500 deaths, the CDC said.

Residents of long-term care facilities, adults aged 65 or more years and adults with chronic conditions — such as diabetes, asthma, heart disease or stroke — are among the populations most at risk for complications stemming from the flu. “In recent years, for example, it’s estimated that between 70% and 85% of seasonal flu-related deaths have occurred in people 65 years and older, and between 50% and 70% of seasonal flu-related hospitalizations have occurred among people in this age group,” the agency said in a website post.

A flu vaccine is the best way to protect against flu and its potentially serious complications, the CDC said, noting that people aged 65 or more years and older should get one of three higher-dose or adjuvanted flu vaccines available — including Fluzone High-Dose Quadrivalent, Flublok Quadrivalent or Fluad Quadrivalent — because such vaccines are potentially more effective than standard dose unadjuvanted flu vaccines.

Health officials recommend vaccination for long-term workers as well.

All flu vaccines for the 2023-2024 season are quadrivalent vaccines (protecting against four different flu viruses), but in the future, flu vaccines will go back to being trivalent (protecting against three different flu viruses), according to the CDC.

“Regulatory agencies have recommended that B/Yamagata lineage vaccine viruses be removed from flu vaccines in the future because these viruses have not been detected and, as a result, no human infections with it have been identified since March 2020,” the agency said.