According to a study published in the journal Pediatrics, due to the high risk of excessive needle penetration through the muscle when using CDC needle length guidelines for vaccination, a review of the current approach to intramuscular injection of vaccines into the shoulder and thigh may be necessary.

An intramuscular route of administration is most preferred for the administration of most vaccines in children. For children aged 12 to 18 months, the injections are carried out in the broad thigh muscle, for children over 18 months - in the shoulder deltoid muscle. Correct entry of the vaccine into the intramuscular layer increases immunogenicity and the immune response compared to the subcutaneous or intradermal routes of administration.

The United States Centers for Disease Control and Prevention (CDC) issued recommendations in February 2007 for needle length for intramuscular injection in the thigh and shoulder, taking into account the age of the patient. 'child. For example, the CDC has recommended a 1 inch * needle for all intramuscular thigh injections for immunization of children 1 to 12 months of age, a 1-1.25 inch needle for immunization of elderly children from 12 to 24 months also in the area of the wide hips and muscle 5 / 8-1 inches for all i / m injections of the vaccine in the deltoid muscle in children aged 1 to 18 years. There have already been cases of excessively deep penetration of the needle into the muscle layer, of which a potential risk is damage to the periosteum or bones. At the same time, insufficient penetration of the needle and introduction of the vaccine into the subcutaneous fatty layer can lead to an insufficient immune response to vaccination.

The objective of the study, conducted at the Cincinnati Children's Hospital Medical Center (Ohio, USA), was to determine the optimal needle length for intramuscular vaccination in the thigh and shoulder area in children of different ages based on the results of magnetic resonance imaging (MRI) and computed tomography (CT)

This study is the first study to determine the risk of excessive and insufficient penetration of the needle into the muscle layer during IM vaccination.

The authors studied the results of 250 MRI and CT examinations of the shoulder and thigh in children 2 months to 18 years of age and measured the thickness of the subcutaneous layer of fat and muscle. Regression analysis revealed a correlation of these measures with age and weight.

If we follow the CDC recommendations for needle length for IM vaccination using 1 inch and 1.25 inch needles, this would lead to excessive penetration of the needle through the muscle layer in 11% and 39% cases, respectively, when there is a risk of insufficient needle penetration It would be noted in 2% of cases.

For shoulder vaccinations with CDC needles (5/8, 7/8 and 1 inch), the needle would penetrate excessively deep through the muscle layer in 11%, 55% and 61% of the cases, respectively.

Thus, when using the current CDC recommendations during vaccination, there is a high risk of excessively deep penetration of the needle through the muscle layer.

According to the thickness measurements of the fatty and muscular layers subcutaneous in this study according to MRI and CT, a 7/8 or 1 inch needle is suitable for intramuscular injection in the thigh in children of both sexes under the age of 6, which is in line with CDC recommendations. At the same time, the needle length recommended by the CDC for an i / m injection in the shoulder is too long and leads to penetration of the needle through the muscle to the periosteum and bones in 11%, 55% and 61% of patients using 5/8, 7/8 or 1 inch of needle. This can cause severe pain, damage to bone tissue, as well as reduce the amount of vaccine that has entered the muscle layer, and as a result, the child will develop a less pronounced immune response to vaccination.

Based on the data obtained, the study authors recommend the following needle lengths for IM vaccination in the deltoid muscle of the shoulder:

The implementation of these recommendations should guarantee that in 90% of cases, patients of both sexes will be correctly vaccinated with the needle entering the muscular layer without excessive penetration of the needle through the muscle.

Thus, the authors conclude that the CDC guidelines for the length of vaccination needles should be reviewed. The limitation of this study may be the retrospective design, as well as the uneven weight and age distribution of the patients. In addition, the average statistical mass of children in a city in the United States may not fully reflect the characteristic image of the country as a whole, and the increase in the number of obesity cases among children and adolescents and l Huge variability in the thickness of subcutaneous fat and muscle layers can hinder the development of universal recommendations for needle length for IM vaccination.