Flublok Flu Shot

Flublok Vaccine

Flublok is an egg-free flu vaccine for people over 18 years old. Unlike most other flu shots, Flublok is made in insect cells and it contains a flu virus protein rather than inactivated flu viruses.

What is Flublok?

Flublok® is a vaccine against influenza (“the flu”) that was developed by Protein Sciences Corporation. It is the first insect-based flu vaccine that can be given to people with severe egg allergies. Flublok Trivalent (three-strain) was approved in 2013. Flublok Quadrivalent (four-strain) was approved in 2016. Both are approved for adults who are at least 18 years old.

How is Flublok made?

Unlike other flu shots, Flublok is not made in eggs. Instead, Flublok is an insect-based flu shot. The manufacturing process involves programming insect cells that are grown in steel tanks to produce large amounts of a flu virus protein called hemagglutinin. This process can make a lot of vaccines far more quickly than egg-based vaccines, which is a big advantage in the event of a pandemic.

What insect helps make Flublok?

Flublok is made using the cells of Spodoptera frugiperda, a common pest known as the “fall armyworm” that mainly attacks corn crops. It is a type of moth that is native to North America.

How is Flublok given?

Flublok is given in a single 0.5-mL injection in the upper arm.

Can Flublok give you the flu?

No. Flublok contains non-infectious proteins that can’t cause the flu. In clinical trials, about 1-2% of people developed mild flu-like symptoms (cough, runny nose, sore throat, congestion, etc.) as their body developed immunity, but this is not the flu.

Can anyone get Flublok?

No. Flublok is only for people who are at least 18 years old.

Who should NOT get Flublok?

Flublok is contraindicated in people who are younger than 18 years old. It should not be given to anyone who has experienced a severe allergic reaction to any ingredient in the vaccine (see below for a list).

The decision to give Flublok should be carefully considered in anyone who experienced Guillain-Barré Syndrome (GBS) within 6 weeks of a previous flu shot. The 1967 swine flu vaccine was associated with an increased frequency of GBS.

What are the most common side effects of Flublok?

In adults 18 through 49 years old, the most common side effects of Flublok were pain (37%) where the shot was given, headache (15%), fatigue (15%), muscle pain (11%), nausea (6%), joint pain (4%), and chills (3%).

In adults 50 through 64 years old, the most common side effects of Flublok were pain (32%) and swelling (7%) where the shot was given, headache (17%), fatigue (13%), muscle pain (11%), joint pain (8%), nausea (6%), and chills (5%).

In adults 65 years of age and older, the most side effects of Flublok were pain (19%) and swelling (7%) where the shot was given, fatigue (13%), headache (10%), muscle pain (8%), joint pain (6%), chills (5%), nausea (4%), and fever (3%).

What are severe side effects of Flublok?

  • Allergic reaction
  • Anaphylactoid reactions
  • Anaphylaxis
  • Guillain-Barré Syndrome (GBS)
  • Hypersensitivity reactions
  • Shoulder Injury Related to Vaccine Administration
  • SIRVA

What ingredients are in Flublok?

Flublok contains 45 micrograms (mcg) of hemagglutinin (HA) for each of the three flu strains, for a total of 135 mcg HA per 0.5-mL vaccine. Flublok has about 3X the amount of HA compared to other flu shots.

A single 0.5 mL dose of Flublok contains sodium chloride (4.4 mg), monobasic sodium phosphate (0.195 mcg), dibasic sodium phosphate (1.3 mg), and polysorbate 20 (Tween® 20) (27.5 mcg).

Each 0.5 mL dose of Flublok may have residual amounts of baculovirus and Spodoptera frugiperda cell proteins (≤14.3 mcg), baculovirus and cellular DNA (≤10 ng), and Triton X-100 (≤100 mcg).

Does Flublok have thimerosal?

No. Flublok does not contain thimerosal, which is a mercury-based preservative, or any antibiotics or adjuvants.

Where can I get more information?

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