Influenza is a respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. Vaccination remains a primary defense against this contagious disease, reducing illness severity, preventing hospitalizations, and lowering the risk of flu-related complications. Annual flu vaccination protects individual health and contributes to broader public health by limiting viral spread.
Understanding Flu Vaccine Administration Methods
Flu vaccines are administered through various methods. Intramuscular (IM) injection is the most common approach, delivering an inactivated vaccine into a muscle. The intranasal spray uses a live attenuated influenza vaccine (LAIV) delivered into the nostrils. Subcutaneous injection, delivering vaccine into fatty tissue below the skin, is less common but used for certain vaccines.
The choice of administration route depends on the specific vaccine type and the patient’s age and health status. Inactivated vaccines, containing non-infectious, killed viruses, are given via IM injection. The intranasal spray vaccine (FluMist) contains live, weakened viruses and is administered directly into the nasal passages. Each method has guidelines to ensure the vaccine reaches the appropriate tissue for an optimal immune response and to minimize adverse reactions.
Step-by-Step Guide for Intramuscular Injections
Administering an intramuscular flu vaccine requires attention to patient safety and vaccine efficacy. Begin by preparing the injection site by cleansing a two-inch area of the deltoid muscle with an alcohol swab, moving outward in a circular motion, and allowing it to dry.
A 22- to 25-gauge needle is commonly used. For adults, a 1- to 1.5-inch needle is sufficient. A 5/8-inch needle may be used for individuals under 130 pounds (60 kg) if the skin is stretched taut and injected at a 90-degree angle. For infants 6 months and older, a 1-inch needle is recommended.
The deltoid muscle in the upper arm is the preferred site for adolescents and adults. To locate this site, find the acromion process (bony point at the shoulder’s end) and measure approximately two inches below it, above the armpit. For infants, the anterolateral thigh is the site for IM injections.
When administering the vaccine, hold the syringe like a dart with your dominant hand and insert the needle at a 90-degree angle with a quick thrust into the thickest part of the muscle. Steadily depress the plunger to inject the contents; aspiration is not necessary. After injection, withdraw the needle quickly at the same angle it was inserted. Immediately activate the needle’s safety feature and dispose of the used needle and syringe in a puncture-proof sharps container. Apply light pressure to the injection site with a dry cotton ball or gauze, then cover with a bandage if needed.
Administering Nasal Spray and Other Forms
Administering the intranasal flu vaccine (e.g., FluMist) differs from injections. This vaccine is for intranasal administration only and should not be injected. To begin, the patient should be in an upright position.
Remove the rubber tip protector from the sprayer, but do not remove the dose-divider clip. Gently place the tip of the sprayer just inside one nostril. The patient should breathe normally. With a single, rapid motion, depress the plunger until the dose-divider clip stops it, then remove the sprayer from the nostril.
Pinch and remove the dose-divider clip from the plunger. Insert the tip just inside the other nostril and, with another single, rapid motion, depress the plunger to deliver the remaining vaccine. If the patient sneezes, drips, or swallows after administration, the dose is still considered valid, and no re-administration is necessary. Dispose of the used applicator in a sharps container.
Subcutaneous injections, less common for flu vaccines, deliver vaccine into fatty tissue below the skin at a 45-degree angle. A 5/8-inch, 23- to 25-gauge needle is used for subcutaneous injections. For infants under 12 months, the anterolateral thigh is the site. For individuals 12 months and older, the upper triceps area of the arm is used. Pinching the skin might be necessary to ensure the vaccine is delivered into the subcutaneous tissue.
Essential Considerations for Safe Vaccination
Before administering any flu vaccine, confirming the vaccine’s expiration date is important. Using expired vaccines, diluents, or equipment must be avoided. Proper storage of flu vaccines is important to maintaining their potency. Inactivated flu vaccines should be stored in a refrigerator at temperatures between 35°F and 46°F (2°C to 8°C) and should never be exposed to freezing temperatures. Storing vaccines in the center of the refrigerator, away from the freezer compartment and the door, helps maintain consistent temperatures.
Verifying the correct dosage based on the patient’s age and the specific vaccine product is also important. For instance, inactivated influenza vaccine for ages 6 to 35 months might be 0.25 mL, while for ages 3 years and older, it is 0.5 mL. Screening for contraindications and precautions before vaccination helps prevent adverse reactions. Conditions such as a severe allergic reaction to a previous flu vaccine component or an acute febrile illness may require deferring vaccination.
Patients should be vaccinated while seated or lying down to help prevent syncope (fainting), and observation for at least 15 minutes after receiving the vaccine is recommended. Gloves are not always required unless there is a likelihood of contact with infectious body fluids or open lesions on the vaccinator’s hands. After vaccination, common mild side effects like soreness at the injection site, low-grade fever, or muscle aches can occur, usually resolving within one to two days. Patients should be advised on these potential reactions and when to seek medical attention for more serious or prolonged symptoms.