Anti-Flu virus immunoglobulin G (IgG) antibody, serum

What This Test Measures

The test detects IgG antibodies specific to flu viruses, which your immune system creates after exposure. These antibodies remain in your blood for months or years, helping your body defend against future flu infections. This test is often used to determine if you’ve been previously exposed to the flu virus, even if you didn’t get sick.

Why It’s Done

Your healthcare provider may order this test if you’ve had symptoms of the flu recently, or if you’re at higher risk of complications from flu exposure (e.g., chronic health conditions, elderly adults, or those with weakened immune systems). It can also help confirm if you’ve developed immunity after vaccination or past infection.

How It Works

A blood sample is taken from a vein in your arm. The sample is then tested using an immunoassay method to identify flu-specific IgG antibodies. This process detects the presence and concentration of these antibodies without measuring the virus directly.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small bruise or slight discomfort at the injection site, but this usually goes away quickly. If you’re on blood-thinning medication, let your provider know before the test.