What are titers?

Question 9 of A Parent’s Guide to Vaccines: A Conversation About Vaccines for New Parents

A titer is a ratio used to explain the amount of something in a solution. When talking about vaccines or immunity to disease, titers identify the amount of antibodies in a person’s blood.

2016_1_27 0 istock - what are titers squareAntibodies are proteins that can be found circulating through your body. It is their job to find and remove potential pathogens like viruses and bacteria.

Detecting the types and amount of circulating antibodies can tell your doctor:

  • If you are immune to a disease (IgG)
  • If you actively have a disease (IgM)
  • If you are having an allergic response (IgE)

Titers are important because you could have been exposed to a disease, not shown symptoms, and developed immunity without even knowing it. This can be the case for some vaccine preventable diseases like chickenpox or measles. When this happens, vaccination is unnecessary, because your body is already protected.

In other cases, titers are important because you may have become immune to a disease after one vaccine dose, when two or more are required. This is the case for 93% of the population who become immune after one dose of the measles, mumps, and rubella (MMR) immunization. Only about 7% of vaccinated individuals actually need the second dose to complete immunity, according to the CDC.

The goal of the national vaccination program is not to simply increase vaccination rates, but to create immunity to potential diseases. If your titers show that you are already immune, you may not need another vaccine dose for that disease.

Remember, immunity is not always permanent. If your titers show that you are currently immune, you may need to be retested again in the future to ensure that you have retained that immunity.

A Side Note: Titers, MMR, and New Jersey

In New Jersey, parents have the option to have their child tested for titers that would show immunity to MMR before getting vaccinated a second time, and opt out of the second vaccine if the test comes back showing an adequate amount of antibodies.

This option is actually a law, nicknamed Holly’s Law, after a NJ family lost their daughter from an adverse vaccine reaction to her second MMR vaccine, a requirement for her to attend kindergarten.

The logic behind Holly’s law is that those who are already immune from their first vaccination no longer need to be vaccinated.

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Carole Avin

A Bone biopsy showed 5.2 titer results. What is the range of numbers that would indicate Shingles present but with no rash.

Denise Ford

My three children didn’t develope titers to their vaccines. They are adults and are being vaccinated again for their work positions. Could this be genetic?

Focus For Health Team

According to researchers at MedUni Vienna, genetic predisposition in certain HLA subgroups may contribute to having a high level of an immune system messenger substance called interleukin-10, which can play a part in the formation of regulatory T and B cells that slow down immune response to vaccination. This can potentially cause siblings to fail to form or maintain titers for several different vaccines (especially Hepatitis B). The CDC, however, states that most vaccine failure can be blamed on vaccines that were improperly stored (wrong temperature) or given after the expiration date. It is estimated that approximately 10% of individuals do not develop any response to some vaccinations independent of genetic predisposition. This could be caused by their current immune status at the time of immunization. In other cases, a good response to the vaccine is accomplished, but wanes over time. This is especially true of the DTaP combination vaccine, which now requires 6 doses to induce and maintain titers. Research on the exact cause of vaccine failure is ongoing, with no definitive answer in most cases.

Deanna Godines

Do you know if California accepts Titers Testing in place of vaccinations for school age kids?


Do you have percentages of immunity after each dose of other vaccines like you have for mmr?


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