Our Process

Most other licensed flu vaccines are made by using a process that dates back to the 1950s. Not us! We use 21st century technology that lets us make a vaccine without the use of eggs, preservatives (e.g., thimerosal, a mercury derivative), live flu virus or antibiotics. Plus, we can include more active ingredient in each vaccine.

What we do

Rather than make the whole flu virus like the others do, we make only the small piece of the virus that is needed for immunity. This piece is called the hemagglutinin, or HA protein. We do this by taking the genetic information that tells cells how to make the HA protein and putting it into cultured cells that are grown in large stainless steel tanks. These cells act as powerful protein-producing machines and make hundreds of copies of the HA protein. We then purify these proteins and package them into Flublok. Each Flublok dose contains HA proteins that match the three most prominent flu viruses circulating during a given year, so that you are maximally protected.

To learn more about our technology, click here.

Safety Information

Flublok is approved for people 18-49 years old to prevent influenza disease. The most common side effect from Flublok is pain at the site of injection. Other side effects may occur and include fatigue, headache and muscle aches.

Flublok should not be administered to anyone with a severe allergic reaction (e.g., anaphylaxis) to any vaccine component. Flublok does not contain any preservatives (e.g., thimerosal, a mercury derivative), antibiotics, egg proteins or latex.

Tell the doctor if you have ever experienced Guillain-Barré syndrome (severe muscle weakness) within 6 weeks of receipt of a previous dose of influenza vaccine. If you notice any other problems or symptoms following vaccination, please contact your healthcare professional immediately. Vaccination with Flublok may not protect all individuals.

Please see the complete Package Insert for more information.