Shoulder Injury Related to Vaccine Administration (SIRVA) happens when a vaccine is injected too high or too deep into the shoulder, damaging the tissues, tendons, or bursa around the joint. It is often diagnosed as a bursitis injury.

SIRVA is the most common type of vaccine injury. It is not caused by the vaccine itself, but by the needle going into the wrong place. The injury can make normal range of arm movement painful or difficult.

People with SIRVA usually feel sharp pain, weakness, or limited range of motion in the shoulder within 48 hours of the shot. The pain often keeps people up at night, and generally worsens during the winter months.

Treatment often includes anti-inflammatory medication, physical therapy, and sometimes steroid injections. Surgery may even be needed to repair tissue damage. Recovery can take weeks to years, and some people are left with long-lasting or even permanent pain or stiffness.

Guillain-Barré Syndrome is a rare condition where the body’s immune system attacks the nerves. It can sometimes happen after a vaccination. The attack damages the protective coating around nerves, causing them to misfire.

Symptoms often start with tingling or weakness in the legs and can spread upward to the arms and face. Muscles needed for breathing can even be affected, making hospitalization necessary.

Treatment usually includes IV immune globulin (IVIG) or plasma exchange to reduce the immune response. A full recovery is possible, though it can take months or years, and some victims are left with lingering weakness.

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is similar to GBS but lasts longer and can come on more slowly. It’s an autoimmune condition that attacks the body’s nerves, causing long-term damage. While GBS develops over days or weeks, CIDP may build gradually over months.

People with CIDP often have persistent weakness, numbness, and balance problems. Treatment focuses on controlling the immune system with IVIG, corticosteroids, or plasma exchange. Ongoing therapy helps maintain strength and mobility.

Some people improve completely, but others need long-term medical care to keep symptoms under control.

Transverse myelitis is inflammation of the spinal cord, which disrupts communication between the brain and body. This can sometimes happen after vaccinations, if the immune system reacts to the administration of the vaccine by attacking spinal cord tissue.

The condition often causes sudden weakness, numbness, or tingling in the legs and arms, and sometimes bladder or bowel problems. Treatment includes high-dose steroids to reduce inflammation and physical therapy to regain strength and movement.

Some people recover fully within weeks, while others may need long-term rehabilitation for partial improvement.

Vaccinations can be performed correctly and still result in injury. This may happen if the patient is allergic to some ingredient in the vaccine, such as egg ingredients. Injuries may vary, but the most common allergic reactions are covered below.

Anaphylaxis is a severe allergic reaction that can occur shortly after a vaccination. It happens when the body’s immune system overreacts to a component of the vaccine. The reaction can affect breathing, blood pressure, and heart function within minutes.

Symptoms include hives, swelling of the lips or throat, shortness of breath, dizziness, or fainting. It is a medical emergency treated with epinephrine (an EpiPen) and close monitoring in a hospital. Most people recover fully once treated, but follow-up care with an allergist helps identify the cause and prevent future reactions.

Encephalitis is inflammation of the brain tissue, usually caused by infection or a strong immune reaction, occasionally following vaccination. The swelling affects brain function and can cause serious neurological problems if not treated quickly.

Symptoms can include fever, confusion, headache, seizures, or behavior changes. Treatment depends on the cause and may include antiviral medication, corticosteroids, and supportive hospital care. Recovery can take weeks, and while many improve fully, some are left with memory or coordination problems.

Vasovagal Syncope is a brief loss of consciousness caused by a sudden drop in heart rate and blood pressure. It often occurs right after a shot because of fear, pain, or anxiety, not the vaccine itself.

The person may feel dizzy, light-headed, or nauseous before fainting. Recovery is usually quick — lying down or elevating the legs helps restore blood flow to the brain. Treatment isn’t usually needed, but medical staff observe the person to ensure it’s not something more serious.