The influenza vaccine, commonly known as the flu shot, protects against various influenza viruses. Its primary purpose is to help individuals develop immunity, preventing severe illness and reducing the spread of seasonal flu. Because influenza viruses change rapidly, new vaccine versions are developed annually to offer protection against expected prevalent strains. This yearly vaccination is recommended for nearly all people over six months of age to support public health.
Types of Flu Vaccines and Their Administration Methods
Two primary types of flu vaccines are available, each with a distinct administration method. The most widespread is the inactivated influenza vaccine (IIV), which contains killed virus particles. This vaccine is administered as an intramuscular (IM) injection, typically into the deltoid muscle in the upper arm for adults and older children, or the anterolateral thigh for infants and younger children. This form is suitable for most age groups, including infants as young as six months and pregnant individuals.
The other type is the live attenuated influenza vaccine (LAIV), known as the nasal spray flu vaccine, which contains weakened live viruses. This vaccine is delivered as a spray into each nostril, offering a needle-free alternative. The nasal spray vaccine is approved for healthy individuals between the ages of 2 and 49 years. However, it is not recommended for pregnant women, immunocompromised individuals, or those with specific underlying medical conditions.
What to Expect During Vaccine Administration
Before administering any flu vaccine, healthcare professionals follow a standardized protocol to ensure patient safety and proper delivery. This process begins with thorough hand hygiene, verification of the patient’s identity, confirming consent, and checking for any contraindications.
For the flu shot, the healthcare provider selects the injection site, which is the deltoid muscle in the upper arm for adults and older children. For infants, the anterolateral thigh is the preferred site. The chosen area is then cleaned with an antiseptic wipe. The needle is inserted into the muscle at a 90-degree angle with a quick, smooth motion, and the plunger is depressed to deliver the entire vaccine dose. After administration, the needle is swiftly removed, and pressure is applied to the injection site with a dry cotton ball or gauze for several seconds. A bandage may be applied if there is any bleeding.
Administering the nasal spray flu vaccine involves a simpler, non-invasive process. The patient should be in an upright position. The healthcare professional places the tip of the single-use sprayer just inside one nostril and depresses the plunger rapidly to deliver half of the vaccine dose. The dose-divider clip is then removed, and the remaining vaccine is delivered into the other nostril in the same manner. Patients can breathe normally throughout this process; if sneezing, dripping, or swallowing occurs immediately after administration, it does not require a repeat dose as sufficient vaccine is still absorbed.
After Receiving Your Flu Vaccine
Following flu vaccine administration, patients may be asked to remain at the vaccination site for a short observation period, typically around 15 minutes, to monitor for any immediate adverse reactions. This precaution allows healthcare providers to promptly address any rare, severe allergic responses, such as anaphylaxis.
Mild and temporary side effects are common in the hours and days following vaccination, indicating the body is building protection. These can include soreness, redness, or swelling at the injection site for the flu shot, as well as general symptoms like a low-grade fever, headache, muscle aches, or fatigue. These “flu-like” symptoms are generally milder than actual influenza and resolve within one to two days. Applying a cold compress to the injection site or taking over-the-counter pain relievers can help manage discomfort. However, if symptoms are severe, persistent, or include signs of a serious allergic reaction like difficulty breathing, swelling of the face or throat, or dizziness, immediate medical attention should be sought.