Needle in the Wrong Spot can Turn Injection into a Big Pain

misplaced vaccine injury
Vaccine shots aren’t pleasant, but they are necessary for keeping diseases at bay. That said, it takes expertise and great care to properly administer a vaccine shot. Without the right skills, a misplaced vaccine injury can occur, leading to short or long-term injury to the patient.

What’s the Right Way to Administer a Vaccine?

Different types of medication require different methods of administration. The safest method of administration is always the method recommended by the vaccine’s manufacturer. Administering the medication any other way endangers the patient’s health.

Most injectable vaccines are intramuscular injections. Intramuscular administration is suitable when no other method will safely and effectively deliver the dose. For example, if an intravenous injection will irritate the veins, intramuscular injection is a safer alternative. 

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Intramuscular Injection Sites

Intramuscular injection involves injecting the vaccine into muscle tissue. That’s because muscle tissue has a high blood supply and can safely hold a large volume of medication. The safest intramuscular injection sites are:

Arm Deltoid Muscle 

The deltoid muscle is a popular location for most vaccinations, including flu shots. It’s easy to reach and doesn’t require disrobing. That said, because of the small muscle size, the site isn’t ideal for injection doses higher than 1 milliliter.

Thigh Vastus Lateralis Muscle 

The thigh location is not a common choice for vaccination shots. But it is a popular choice for self-administering an injection.

Hip Ventrogluteal Muscle 

Of all the injection sites, this is the safest for anyone above seven months old. That’s because it’s large and has fewer nerves and major blood vessels. Fewer nerves and vessels mean there’s a lower risk of injury during the injection.

Buttocks Dorsogluteal Muscles 

The buttocks muscles are no longer the preferred injection site due to the high risk of injuring the sciatic nerve. Damaging the nerve can cause reduced mobility of the leg.
vaccine injury

What Happens If You Get a Flu Shot in the Wrong Spot?

The National Institute of Health recommends injecting vaccinations, including flu shots, into the anterolateral muscle in the thigh, or the deltoid muscle in the arm. The Center for Disease Control (CDC) has similar recommendations – Anterolateral thigh muscle for children under three years, and deltoid arm muscle for anyone above three years old.

These muscles are ideal because of their high blood supply, which boosts the vaccine’s effectiveness. The high blood flow also minimizes the risk of an adverse reaction at the injection site. But despite the suitability of these sites for flu shots and other intramuscular vaccines, accidents can still happen.

For example, the healthcare provider may miss the muscle and inject the vaccine into subcutaneous fat beneath the skin. When this happens, an insufficient dose may enter the bloodstream, meaning the patient won’t have the necessary protection.

The same mistake can lead to even graver consequences, such as an adverse reaction at the injection site. The reaction may occur because the subcutaneous fat has no blood flow, which causes the vaccine to stagnate in the fat and cause severe inflammation, or worse, necrosis. 

Signs of Flu Shot Injury

A flu shot injury may be due to the needle hitting a nerve or bone, or the needle not being long enough to reach its target. It could also be due to injecting the wrong site.

The discomfort from the injury may initially feel like regular injection discomfort, but you should consult a doctor if the following symptoms persist:

  • Tingling or numbness at the injection site
  • Severe pain 
  • Continuous bleeding
  • Redness or swelling at the injection point
  • Abscess at the injection site
  • Difficulty breathing, facial swelling, or other allergic reactions
  • SIRVA (Shoulder Injury Related to Vaccine Administration)

What is SIRVA?

SIRVA is a shoulder injury that occurs after a misplaced injection into the deltoid muscle. The injury can lead to a short-term reduction in mobility or permanent loss of range of motion in the affected arm.

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SIRVA typically occurs when an injection is too high up in the deltoid muscle. When that happens, the needle penetrates the shoulder’s rotator cuff or the bursa (sac of lubricating fluid). Injecting either will cause severe and lasting pain. It could also lead to long-term loss of movement of the shoulder.

According to the Vaccine Adverse Event Reporting System (VAERS), cases of SIRVA are on the rise. For some patients, symptoms last from six months to several years, while 30% of patients require surgery.

What Happens if a Flu Shot is Given Subcutaneously?

For many years, the buttocks were the preferred site for flu shots and other vaccinations. But that changed with a rise in sciatic nerve injuries and accidental subcutaneous fat injections.

Accidental subcutaneous fat injections cannot get a vaccine dose into the bloodstream fast enough. That’s because there isn’t enough blood flow in the fatty layers to circulate the vaccine. Also, while in the fat layers, enzymes can begin denaturing the vaccine’s antigens, leading to a less potent dose and an episode of vaccine failure. 

Another problem is fat layers do not contain the phagocytic or antigen-presenting cells for triggering an immune response. These factors are why healthcare experts recommend administering flu shots intramuscularly. 

But according to the CDC, if there is an accidental subcutaneous administration of an intramuscular flu shot, it is best to simply repeat the injection. The second injection ensures the patient gets the right dose and reduces the risk of vaccine failure. 

That said, aside from reduced effectiveness, subcutaneous injections, accidental or deliberate, come with the risk of abscesses and granulomas. Because of the health risks involved, it’s best to avoid injecting subcutaneously whenever possible.
arm injury cause by vaccines

Do I Have Any Recourse After Getting A Flu Shot In The Wrong Spot?

A misplaced vaccine injury can cause untold pain and suffering. For example, patients with an immobilized limb from the injury may no longer be able to work, causing hardship for them and their dependents.

Fortunately, victims of misplaced vaccine injury can get financial compensation by filing a petition through the proper channels. Instead of filing a lawsuit, which costs more time and money, a claimant can seek restitution through the National Vaccine Injury Compensation Program (VICP).

From 1988 to 2020, the program has paid vaccine injury victims over $4 billion in compensation. But you can only file a petition for damages if the VICP covers the vaccine that caused the injury. The flu shot is a covered vaccine.

Best Locations for Injections

Reduce the risk of a misplaced vaccine injury by injecting vaccines into a site with minimal risk of vascular, neural, or tissue injury. Depending on the age of the patient and vaccine quantity, the optimal injection site could be the deltoid muscle or anterolateral thigh muscle. 

Larger doses should go into the anterolateral thigh muscle, while smaller doses (under 1 milliliter) should go into the deltoid.

Also, if administering two vaccines at once, space them 1-inch apart. Doing so will prevent the vaccines from mixing and possibly causing an adverse reaction.

Aside from injecting the vaccine into the right location, the length of the needle is also important. If the needle isn’t long enough, it could end up injecting the vaccine subcutaneously.

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It's important that you start the process as soon as possible.
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For infants under 1-month-old, a 5/8-inch needle is ideal for an anterolateral thigh injection. For a 1 through 12-month old infant, a 1-inch needle is enough for an intramuscular injection. The same goes for adults that weigh under 150 pounds. An adult that weighs over 150 pounds may require a 1½-inch needle to get through the fat layers and into the muscle.

But the needle must also not be too long. If it is, it could damage blood vessels, nerves, or skeletal structures. 


Modern medicine has given us many benefits, including vaccines. But a misplaced vaccine injury can turn a life-saving medication into a health risk. To avoid complications, make sure a healthcare professional administers all your vaccinations.

If something goes wrong, don’t hesitate to seek damages through the Vaccine Injury Compensation Program.


You Only Have Three Years To File Your Claim

The first step in helping yourself or a loved one after a serious vaccine related injury is to contact us for a free review of your case.

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