Flu activity is low in most of the United States, but influenza viruses are still causing illness. CDC continues to recommend vaccination as long as flu viruses are still circulating. And remember that flu antiviral drugs are a second line of defense to treat flu illness. People at high risk of serious flu illness should call a health care provider if they get flu symptoms.

What You Should Know for the 2013-2014 Season

How Influenza (Flu) Vaccines Are Made

There are three different influenza vaccine production technologies approved by the U.S. Food and Drug Administration (FDA): egg-based flu vaccine, cell-based flu vaccine, and recombinant flu vaccine. All commercially available flu vaccines in the United States are made by private sector manufacturers. Different manufacturers use different production technologies, but all flu vaccines meet FDA safety and efficacy requirements. The different vaccines are approved with different indications.

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