Most vaccines on the National Immunisation Program (NIP) are administered via intramuscular or subcutaneous route. Correct injection technique is of paramount importance when administering vaccines to ensure optimal immune response, minimise side effects and to reduce the risk of injury to the patient.

Preparing the site for injection

The skin at the injection site should be visibly clean prior to administering a vaccine. The swabbing of clean skin before giving an injection is not necessary. If the skin is visibly dirty, clean the site with alcohol wash/single use alcohol swab and allow the site to dry completely before administering the injection. If active/infected eczema is present at the recommended site, consider an alternate site to minimise the risk of injection site abscess. If there is no alternate site suitable, consider cleaning the site with an alcohol based wash/single use alcohol swab and allowing the site to dry completely before injecting.

Recommended injection sites by age

Infants < 12 months

The recommended injection site is the middle third of the vastus lateralis (anterolateral thigh).

To locate the correct anatomical site for injection:

  • ensure the infant’s leg is completely exposed
  • locate the upper and lower anatomical landmarks- greater trochanter of femur and patella
  • draw an imaginary line between the 2 landmarks down the front of the thigh
  • then imagine the thigh is divided into thirds
  • the correct injection site is located in the middle third and on the outer aspect of the imaginary line (see images below).

Where only two vaccines are scheduled it is recommended to give one vaccine into each thigh. If more than two vaccines are recommended at the one visit, two vaccines may be given into each thigh ensuring they are separated by 2.5 cm.

Do not inject into the anterior aspect of the thigh as underlying structures may be damaged.

In some circumstances (eg; congenital limb malformations, active eczema or hip brace placement) alternate sites should be considered. In these scenarios, alternate sites include the deltoid or opposite anterolateral thigh (ensuring that each vaccine has a 2.5cm spacing).

Children ≥ 12 months of age, adolescents and adults

The recommended injection site is the deltoid (upper arm).

To locate the correct anatomical site for injection:

  • expose the arm completely from the top of the shoulder to the elbow; remove shirt or clothing if needed
  • locate the upper and lower anatomical landmarks- acromion (shoulder tip) and the muscle insertion of the deltoid (deltoid tuberosity)
  • draw an imaginary inverted triangle below the shoulder tip, using the identified landmarks (see images below)
  • the site for injection is halfway between the acromion and the deltoid tuberosity, in the middle of the deltoid muscle (triangle).

More than one vaccine can be given into the deltoid muscle ensuring each vaccine is separated by 2.5cm.

For children at 12 and 18 months of age the anterolateral aspect of the thigh may be used as an alternate site when giving more than 2 vaccines [see resources].

Recommended needle size, length and angle for administering vaccines

Age or size of the patient Needle type Angle of needle insertion
Infant, child or adult for IM injection 22 – 25 gauge, 25mm in length
Preterm infant or very small infant for IM injection 23 – 25 gauge, 16mm in length
Very large/obese patient for IM injection 22 – 25 gauge, 38mm in length
Subcutaneous injection in all patients 25 – 27 gauge, 16mm in length

* Table adapted from the Australian Immunisation Handbook

Implications of incorrect injection technique

Injection site reactions are more likely following inadvertent administration into subcutaneous tissue as opposed to the intended muscular tissue.

Shoulder injury related to vaccine administration (SIRVA) is a rare complication of incorrect vaccine administration causing an immune-mediated inflammatory reaction within the shoulder joint. When a vaccine is given into the shoulder joint (too high) it can cause a sudden onset of pain and limited range of movement which can persist for variable lengths of time and require medical investigations and treatment.

Impaired immune response can follow administration of vaccines utilising an incorrect injection technique. Depositing vaccines into the subcutaneous tissue (when muscular tissue was intended) or into the joint can lead to a decreased immune response to the vaccine.


Authors: Mel Addison (SAEFVIC Research Nurse, Murdoch Children’s Research Institute) and Rachael McGuire (SAEFVIC Research Nurse, Murdoch Children’s Research Institute)

Reviewed by: Rachael McGuire (SAEFVIC Research Nurse, Murdoch Children’s Research Institute)

Date: July 2020

Materials in this section are updated as new information and vaccines become available. The Melbourne Vaccine Education Centre (MVEC) staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family’s personal health. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult a healthcare professional.