Why do vaccines need to be given in different arms?

Vaccines injected into different parts of the human body will produce varying degrees of antibody responses. Among them, injection into the deltoid muscle has the highest antibody response titer, and injection into the buttock muscle has the lowest titer. Those injected into the deltoid muscle and buttock muscles have a moderate antibody response. . The deltoid muscle is closer to the armpit lymph nodes, which is conducive to the production of immunity.

In fact, when I was a child, vaccinations were mainly for the arms, but other injections were mainly for the buttocks. Nowadays, vaccines are occasionally injected into the inner thigh or taken orally, but they are mainly injected into the arm.

Why is this?

Let me talk about a secondary reason first. It is that spanking the arm is much more convenient than spanking the buttocks. In the past, when spanking the buttocks, there was always a popular joke like "you have to take off your pants", which is actually a kind of helplessness and embarrassment.

But it is much more convenient to hit the arm, and there is no need to take off the pants.

Let’s talk about the important reasons.

In fact, it is because there is a lot of fat tissue in the buttocks of the vaccine, and the blood circulation in the fat layer is poor, which reduces the vaccine absorption efficiency and reduces the contact between phagocytes (antigen presenting cells) and pathogenic antigens, thus affecting the processing The pathogen antigens after injection are transferred to immune active cells, resulting in low titer of antibodies produced after injection and rapid decline, seriously affecting the immune effect of the vaccine. The key point is that the effectiveness of the spanking vaccine is poor. If it is too poor and cannot play the role that the vaccine should have, then the gain outweighs the loss.

And why do you need to change your hands? Last time I was vaccinated on my left hand, this time I basically had to switch to my right hand.

This is actually to ensure the absorption effect of the vaccine, because after some vaccines are administered, there will be hard tuberculosis, which will take a certain amount of time to dissipate, and the presence of hard tuberculosis is also not conducive to vaccine absorption. .

Generally speaking, no matter what drug is injected, it is injected into the muscle. Why the vaccine should be injected on the arm instead of the butt is actually very simple. It has something to do with the amount of injection. Generally, it is easier to absorb the drug when it is injected into the muscle, while spanking injections are generally only used when the dosage of the drug is relatively large, usually 1-2ml. This is because the gluteus maximus muscle on the buttocks is relatively developed and is conducive to large-dose injections.

The injection volume of general vaccination is very small, about 0.1-0.5ml. Sometimes 1ml is also injected. It is usually injected into the triceps brachii on the left arm of the person. The muscles in this area are relatively developed and can meet the injection volume requirements for vaccination. Compared with spanking injections, the applicability here is greater, and the drug will take effect more quickly. It will also reduce the time to take off pants and improve efficiency, which is very conducive to group injections.