Can Vaccines Cause ITP?

ITP is an abbreviation for idiopathic thrombocytopenic purpura.

It is a condition in which our platelets get destroyed, leading to excessive bruising and bleeding, since platelets are needed for normal blood clotting.

What Causes ITP?

To understand what causes ITP, it is important to know it is also often referred to as immune thrombocytopenic purpura, because it is typically the cells of our own immune system that destroys our platelets.

Why?

Well, that’s where the idiopathic part comes in.

We don’t know why people develop ITP, although classically, ITP is thought to follow a viral infection, including Epstein-Barr virus (mono), influenza, measles, mumps, rubella, and varicella (chicken pox). ITP has also been associated with many other viral infections, from Dengue fever to Zika.

“Often, the child may have had a virus or viral infection approximately three weeks before developing ITP. It is believed that the body’s immune system, when making antibodies to fight against a virus, “accidentally” also made an antibody that can stick to the platelet cells. The body recognizes any cells with antibodies as foreign cells and destroys them. Doctors think that in people who have ITP, platelets are being destroyed because they have antibodies.”

Pediatric Idiopathic Thrombocytopenia Purpura (ITP)

These children with ITP, usually under age 5 years, develop symptoms a few days to weeks after their viral infections. Fortunately, their platelet counts usually return to normal, even without treatment, within about 2 weeks to 6 months. Treatments are available if a child’s platelet count gets too low though.

Can Vaccines Cause ITP?

The measles vaccine is the only vaccine that has been clearly associated with ITP.

“The available data clearly indicate that ITP is very rare and the only vaccine for which there is a demonstrated cause-effect relationship is the measles, mumps and rubella (MMR) vaccine that can occur in 1 to 3 children every 100,000 vaccine doses.”

Cecinati on Vaccine administration and the development of immune thrombocytopenic purpura in children

Even then though, the risk of ITP after a measles containing vaccine, like MMR or ProQuad, is much less than after getting a natural measles infection, so worry about ITP is a not a good reason to skip or delay getting vaccinated.

What about other vaccines?

There is no good evidence that other vaccines, including the chicken pox vaccine, DTaP, hepatitis B vaccine, or flu vaccine, etc., cause ITP.

What about Gardasil? ITP is listed in the package insert as an adverse reaction for Gardasil, but only in the postmarketing experience section, so it does not mean that the vaccine actually caused the reaction, just that someone reported it.

Although ITP is listed in the PI for Gardasil, studies have shown that there is no association.
Although ITP is listed in the PI for Gardasil, studies have shown that there is no association.

Several large studies have actually been done that found no increased risk for ITP after getting vaccinated with Gardasil.

What to Know About Vaccines and ITP

Although measles containing vaccines can rarely cause ITP, vaccines prevent many more diseases that can cause ITP.

More on Vaccines and ITP

 

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