Why is The Coronavirus Vaccine Injected Into The Arm?
Some vaccines, such as rotavirus, are given by mouth. Other vaccines are given subcutaneously, such as measles, mumps, and rubella. However, many other vaccines are injected into the muscle. Why are muscles so important?
Immune Cells Are Located in The Muscles
Muscle is a good place to inject vaccines because muscle tissue contains important immune cells. These immune cells recognize an antigen – a small piece of virus or bacteria injected with a vaccine – and trigger an immune response. In the case of the coronavirus vaccine, it is not an antigen that is administered, but an “antigen production plan” that controls antigen production.
Immune cells in muscle tissue pick up these antigens and send them to the lymph nodes. Injecting the vaccine into muscle tissue localizes the muscle tissue and allows the cells to alert other immune cells to start working.
Once the vaccine is recognized by immune cells in the muscle, these cells carry the antigen to the lymphatic vessels, which deliver the antigen-carrying immune cells to the lymph nodes. They contain other immune cells that recognize antigens in vaccines and stimulate the immune process to produce antibodies.
Clusters of lymph nodes are located near the injection site. For example, many vaccines are injected into the deltoid muscle because it sits near the lymph nodes in the armpit. When the vaccine is injected into the thigh, the lymph tract does not need to travel long distances to reach the lymph nodes in the groin.
Muscles Keep The Vaccine Localized
Injection of the vaccine into the deltoid muscle can cause local inflammation or pain at the injection site. Some vaccines that are injected into adipose tissue are at increased risk of irritation and inflammation due to insufficient blood supply to the adipose tissue, which results in malabsorption of some components of the vaccine.
Vaccines that use adjuvants – or components that enhance the immune response to antigens – must be injected into the muscle to avoid widespread irritation and inflammation. Adjuvants work in different ways to stimulate a stronger immune response.
Another factor that determines where the vaccine is administered is muscle size. Adults and children 3 years of age and older are usually vaccinated in the deltoid region of the forearm. However, for young children, the vaccine is given in the middle of the thigh because the muscles in their arms are smaller and less developed.
Another aspect of vaccination is patient comfort. Can you imagine pulling your pants down in a mass vaccination clinic? It’s much easier to roll up your sleeves.
Outbreaks of infectious diseases, for example, during the flu season or epidemics like COVID-19, require our healthcare system to vaccinate as many people as possible in a short period of time, for these reasons it is best to inject the drug into an arm that is easily accessible.
The arm is the preferred vaccination method for most adults and children for influenza and coronavirus vaccines.
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