Tag: immunodeficiency

How Often Should You Do Vaccine Titer Testing?

We sometimes hear about folks doing vaccine titer testing.

A vaccine titer is a blood test that can determine whether or not you are immune to a disease after you get a vaccine.

While that sounds good, after all, why not check and be sure, it has downsides. Chief among them is that the results aren’t always accurate.

That’s right. You can sometimes have a negative titer test, but still be immune because of memory B cells and the anamnestic response.

How Often Should You Do Vaccine Titer Testing?

So how often should you do vaccine titer testing?

It depends, but most folks might never have it done!

Why not?

Vaccines work very well, so you would typically not need to routinely check and confirm that you are immune after being vaccinated. And, this is also important, the vaccine titer tests don’t always work that well, titer testing isn’t available for all vaccines (you can’t do titer testing for Hib and pertussis), and the testing can be expensive.

So we usually just do the testing (a quantitative titer) for folks that are in high risk situations, including:

  • pregnancy – rubella titer only (HBsAg is also done, but that’s not a vaccine titer test, but rather to see if you are chronically infected with hepatitis B)
  • healthcare workers – anti-HBs (antibody to the hepatitis B surface antigen to confirm immunity after being vaccinated)
  • students in nursing school and medical school, etc. – anti-HBs
  • children and adults exposed in an outbreakmeasles, chicken pox, mumps, etc., but only if we are unsure if they were previously vaccinated and protected
  • after a needlestick injury, etc. – to confirm immunity to hepatitis B
  • babies born to a mother with hepatitis B – to confirm that their hepatitis B vaccine worked

Vaccine titer testing might also be done for:

  • internationally adopted children – to confirm that they are immune if we unsure about all of the vaccines the child got in other countries
  • children and adults with lost vaccine records – to confirm that they are immune, since we are unsure about all of the vaccines they got
  • evaluation of children and adults with immune system problems – to help identify what immune system problems they might have – typically involves checking pneumococcal titers, giving Prevnar, and then checking pneumococcal titers again
  • people at continuous or frequent risk for rabies – rabies titer testing every 6 months to 2 years
  • patients with inflammatory bowel disease, before starting immunosuppressive therapy – hepatitis A and hepatitis B titers, as they might be at increased risk for hepatitis

While checking titers is easy, it is sometimes harder to know what to do with the results you get.

Of all of these different titers, only one tells you that you are immune due to vaccination.
Of all of these different titers, only one tells you that you are immune due to vaccination.

It is especially important to know that:

  • most people don’t need to have their titers checked routinely if they are not in one of the high-risk groups noted above
  • it isn’t practical to get titers tested as a method of potentially skipping one or more doses of your child’s vaccines, after all, if the titer is negative, then you are still going to have to get vaccinated
  • a healthcare provider with a negative measles titer after two doses of the MMR vaccine does not need another dose of vaccine
  • a healthcare provider who has anti-HBs <10 mIU/mL (negative titer) after three doses of the hepatitis B vaccine should get another dose of vaccine and repeat testing in 1 to 2 months – if still <10 mIU/mL, they should then get two more doses of hepatitis B vaccine (for a total of 6 doses) and repeat testing. If still negative, these documented nonresponders will need HBIG as post-exposure prophylaxis for any future hepatitis B exposures, but no further doses of hepatitis B vaccine.
  • vaccinated women of childbearing age who have received one or two doses of rubella-containing vaccine and have rubella serum IgG levels that is not clearly positive should be administered one additional dose of MMR vaccine, with a maximum of three doses, and should not be tested again
  • postvaccination titer testing is not recommended after the chicken pox vaccine
  • in addition to not being able to test titers for pertussis and Hib immunity, it is becoming difficult to test poliovirus type 2 titers, as the test uses a live virus that isn’t routinely available anymore (type 2 polio has been eradicated)

Still think you need vaccine titer testing?

More on Vaccine Titer Testing

Is a Family History of Altered Immunocompetence a Contraindication to Getting Vaccinated?

Have you ever wondered why a “family history of altered immunocompetence” is listed as a contraindication to getting varicella and MMR vaccines?

If family members have altered immunocompetence, getting and exposing them to measles isn't a good idea either.
If family members have altered immunocompetence, getting and exposing them to measles isn’t a good idea either.

It’s probably not why you think…

Is a Family History of Altered Immunocompetence a Contraindication to Getting Vaccinated?

Which vaccines are contraindicated if you have a family history of altered immunocompetence?

Typically MMR and Varivax, the chicken pox vaccine.

Is this about side effects?

Kind of.

As they are live vaccines, you don’t usually want to give them to anyone who might be immunocompromised. And since some conditions that cause immune system problems can run in families, if there is a family history of these conditions, you want to make sure your child doesn’t have one before they are vaccinated.

(g) family history of congenital or hereditary immunodeficiency in first-degree relatives (e.g., parents and siblings), unless the immune competence of the potential vaccine recipient has been substantiated clinically or verified by a laboratory.

General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP)

Fortunately, these types of severe immune problems are rare.

They might include:

  • Severe antibody deficiencies (e.g., X-linked agammaglobulinemia and common variable immunodeficiency)
  • Complete defects (e.g., SCID disease, complete DiGeorge syndrome)
  • Partial defects (e.g., most patients with DiGeorge syndrome, Wiskott-Aldrich syndrome, ataxia- telangiectasia)
  • Phagocytic deficiencies that are undefined or accompanied by defects in T-cell and NK cell dysfunction (such as a Chediak-Higashi syndrome, Leukocyte Adhesion Deficiency [LAD], and myeloperoxidase deficiency)

Talk to your pediatrician if your child has a first degree relative with one of these conditions, before they get their MMR or chicken pox vaccines.

Still, by twelve months, infants with a severe congenital or hereditary immunodeficiency or any other severe immunodeficiency will almost certainly have symptoms already.

Most children, for example, had been diagnosed with severe combined immunodeficiency (SCID), in early infancy when they have severe and life-threatening infections and failure to thrive.

And most newborns in the United States are now screened for SCID as a part of their routine newborn screening test, and can be diagnosed and treated before they have symptoms! That’s also long before they might be due for their MMR or chicken pox vaccines.

So, if your child has a family history of congenital or hereditary immunodeficiency, and it is in a first-degree relative, but has no symptoms themselves, then they can get safely vaccinated on schedule.

Not surprisingly, anti-vaccine folks try to abuse their family history of altered immunocompetence as an vaccine exemption, even when their own child isn’t immunosuppressed!

More on Vaccine Contraindications