As healthcare professionals, it’s important to keep up with the new trends as well as understand why you do certain procedures. With much talk about vaccines in the past few years, we were curious about the placement of vaccine injections and thought others might be too.

According to the National Institutes of Health (NIH), vaccines should usually be administered intramuscularly in the deltoid or anterolateral area of the thigh. This optimizes the immune response of the vaccine. It also reduces any detrimental reactions at the site of injection. The NIH also advises the importance of correct administration of vaccines, including the length of injection needles.

Fatty Tissue Injection Sites

Vaccines may actually fail when administered in fatty tissue. This failure is caused by lowered vascularity and therefore reduced movement of the antigen throughout the body. Influenza vaccines, for instance, form antibody rates in blood serum that are less effective and decay more rapidly. The same is true with Hepatitis B, rabies vaccines, and many others.

In traditional medicine, the buttocks were used for vaccination sites. But the antigen-presenting or phagocytic cells required for the appropriate immune response are not found within layers of fat. Circulation is delayed of the antigen when deposited in fat. Macrophages processing and the overall effect of presentation to B and T cells involved in the immune response is greatly slowed. Also, the denaturing of antigens by enzymes is caused when left in fat for days or even hours. It has been found that thicker skinfolds are identified with an antibody response to vaccines that is lowered.

Muscular Injection Sites

Muscle has an abundant blood supply. Therefore, its reaction to injections is rarely serious, as injections do not remain long within them, unlike the adipose tissue, which has a poor route of drainage. The muscles do not generally form a local reaction, such as necrosis, granuloma, inflammation, or even irritation, which is why the route should be most commonly used. And because of the dispersal to the blood stream, the vaccine efficacy is much greater, as the response time to make the antibodies is vastly elevated.

You should also consider the size of the needle for injections. This will not only be determined by whether the patient is a child or adult but also which injection technique is used. For instance, pinching the skin may require a longer needle to reach past the subcutaneous tissue.

Though in traditional medicine, fatty tissue was once thought to be the best injection site, the NIH has determined that intramuscular routes are far more effective; antibodies are made more quickly and local reactions are nearly non-existent, due to the quick dispersal of the vaccine.