Tag: negative titers

How Do You Know If You Have Measles Immunity?

With all of the measles cases, you might be wondering if you have immunity to measles?

Are you worried that you might get measles?

Should you get a booster dose of MMR?

Or a titer test?

How Do You Know If You Have Measles Immunity?

Fortunately, most of us can feel confident that we do have measles immunity and that we won’t get caught up in any of the ongoing outbreaks.

Why?

If you have had two doses of MMR, then you can be confident that you have measles immunity.
If you have had two doses of MMR, then you can be confident that you have measles immunity.

Because we are vaccinated and protected!

If you haven’t had two doses of MMR (or any measles containing vaccine since 1967), then understand that two doses is your best protection against measles.

Is There a Blood Test for Measles Immunity?

What about titer tests?

While there is a blood or titer test for measles immunity, it isn’t routinely used.

The one situation in which a measles titer test might be useful though, is for those born before 1957 to confirm that they really had measles.

For others considering a titer test in place of vaccination, it is typically better to just get another dose of MMR, but only if you haven’t already had two doses.

Why Was My Measles Titer Negative?

A positive measles titer does mean that you are immune, but what about a negative measles titer?

“For HCP who have 2 documented doses of MMR vaccine or other acceptable evidence of immunity to measles, serologic testing for immunity is not recommended. In the event that a HCP who has 2 documented doses of MMR vaccine is tested serologically and determined to have negative or equivocal measles titer results, it is not recommended that the person receive an additional dose of MMR vaccine. Such persons should be considered to have presumptive evidence of measles immunity. Documented age-appropriate vaccination supersedes the results of subsequent serologic testing.”

Immunization of Health-Care Personnel: Recommendations of the Advisory Committee on Immunization Practices (ACIP)

If you have had two doses of MMR and have a negative measles titer, you don’t need another dose of MMR. You are likely immune, even with that negative titer.

“Most vaccinated persons who appear to lose antibody show an anamnestic immune response upon revaccination, indicating that they are probably still immune.”

Epidemiology and Prevention of Vaccine-Preventable Diseases

And since you would need a second dose if you had a negative titer after having just one shot, you might as well just get the second dose instead of checking your titer.

Do You Need a Measles Booster?

Have you had two doses of MMR?

If so, then you don’t need another dose.

The second dose isn’t technically a booster anyway. It is just for those who might not have responded to their first dose.

And two doses of MMR are about 97% effective at preventing measles.

That’s why most of the people in measles outbreaks are unvaccianted.

Neither primary nor secondary (waning immunity) vaccine failure are common with the measles vaccine.

What’s the biggest issue with the MMR? Folks who are still too scared to get their kids vaccinated and protected!

More on Measles Immunity

How Could Seven of My Vaccinated Kids Have the Measles Right Now?

Seven vaccinated kids with measles?!?

But doesn’t the measles rash typically show up after three to five days of fever?

Wait, that couldn’t really happen, could it? Seven vaccinated kids with measles in one family?

How Could Seven of My Vaccinated Kids Have the Measles Right Now?

While anything is possible, this story is very improbable once you look at the details…

“When her 12-year-old son spiked a fever and started complaining of a sore throat right before Passover, Mrs. Pearl (not her real name) wasn’t worried. She confidently crossed off a host of possible infections that he was fully vaccinated for.

She thought he had strep throat, like two of his siblings.

They headed to urgent care for a rapid strep test, but the result was negative. Undeterred, she put her son on antibiotics at the nurse’s recommendation, and sent her son to bed.

He’d worsened by morning.

He woke feeling feverish and broken out in a rash.”

Jennifer Margulis

Could that be measles?

He ended up testing positive for measles, even though he was fully vaccinated. Only two days of fever before he developed his rash though, and no word that the fever continued, as you would expect with measles…

“Not long after, Mrs. Pearl’s 10-year-old broke out in a similar rash.

This child didn’t spike a fever but his breathing was labored and he complained that his eyes hurt.

He also tested positive for the measles.”

Jennifer Margulis

Although they all could have been exposed to someone else, it is important to note that the incubation period for measles is 7 to 14 days. The “not long after” scenario sounds like too short a time to get “measles” from his brother. Also, no fever, which would be very strange for measles…

But the other five kids had more classic symptoms of measles, right?

Nope.

“Of the seven other children that Mrs. Pearl had tested—all of whom had been fully vaccinated—five more showed no immunity to measles.”

Jennifer Margulis

What about the negative titer tests?

That’s actually not unusual after measles vaccination. It’s not proof or any kind of indication that the vaccine didn’t work. It has been long known that most vaccinated people who have negative measles titers will show an anamnestic immune response if they get another dose of MMR.

What does that mean? It means that they were likely immune, even with the negative titer.

“In the event that a HCP who has 2 documented doses of MMR vaccine is tested serologically and determined to have negative or equivocal measles titer results, it is not recommended that the person receive an additional dose of MMR vaccine. Such persons should be considered to have presumptive evidence of measles immunity. Documented age-appropriate vaccination supersedes the results of subsequent serologic testing.”

Immunization of Health-Care Personnel: Recommendations of the Advisory Committee on Immunization Practices

In fact, we don’t routinely check titers after MMR, at least not for measles.

And their symptoms?

“Two hours after getting the MMR booster, Mrs. Pearl’s 16-year-old spiked a 102-degree fever and broke out in a measles rash.

Four days later her three other children, all of whom had received the MMR booster, all had measles rashes, canker sores in their mouths, gastrointestinal problems, and lethargy.”

Jennifer Margulis

Canker sores with measles? Kids with measles get Koplik spots, but no one describes them as canker sores.

Fever and a rash developing at the same time?

Yeah, none of that sounds like measles. At all.

Remember, the classic symptoms of measles include 3 to 5 days of a high fever with cough, coryza, and conjunctivitis, followed by a rash, with continued fever.

“According to Mrs. Pearl, the health department official also told her that measles vaccine failure is common and that about half the people getting measles in the current measles clusters in Brooklyn are fully vaccinated.”

Jennifer Margulis

Actually, only 27 of the 566 people in Brooklyn with measles have been known to be fully vaccinated, with two doses of MMR. How much less than half is that? It is less than 5% of cases.

Measles vaccine failure is not common at all.

Why Did They Say That Seven of My Vaccinated Kids Have Measles?

So how do you explain what happened to this family?

Besides the likelihood that they had another, more common virus causing their symptoms? With mouth ulcers and diarrhea, like maybe Coxsackie virus?

Do you really need another explanation?

How do you explain the positive measles tests?

They were almost certainly a false positive.

“The test kits in use have been shown to have high sensitivity and specificity. However, cross-reactions with other viral diseases, e.g. rubella and Parvovirus, may occur.”

Dietz et al on The laboratory confirmation of suspected measles cases in settings of low measles transmission: conclusions from the experience in the Americas.

They didn’t state which test was done, but it is important to note that several are available. This includes an immunoglobulin test, PCR from a throat swab, and PCR from a urine specimen. The most accurate testing is done by the CDC.

“Detection of specific IgM antibodies in a serum sample collected within the first few days of rash onset can provide presumptive evidence of a current or recent measles virus infection. However, because no assay is 100% specific, serologic testing of non-measles cases using any assay will occasionally produce false positive IgM results.”

Serologic Testing for Measles in Low Prevalence Setting

Did they have confirmatory tests, after their initial positive test? Were they done at a state lab? Did all of her other kids test positive for measles?

“She’s angry at the measles vaccine failure and worried about her family members, especially her pregnant daughter.”

Jennifer Margulis

She should be angry at folks pushing misininformation in her community.

“I used to think people who don’t vaccinate were crazy,” Mrs. Pearl says. “Now I’m not so sure. Maybe they’re right. Maybe my body doesn’t want to take garbage. Something is a red flag. After my story, I’m not so sure where the measles started. I’m legit. I did vaccinate. All my kids are up to date. Children ages 22 to 7 all getting the measles?”

Jennifer Margulis

Something is indeed a red flag. To get to the bottom of it, Mrs. Pearl should revisit the idea that her kids really had measles.

More on Vaccinated Kids with Measles

Titers for Vaccine vs Natural Immunity

It probably seems like a silly question, but can titers help you tell the difference between vaccine induced vs natural immunity?

After all, you should know if you had the disease naturally or if you had a vaccine, right?

Titers for Vaccine vs Natural Immunity

Still, there might be situations in which you need to know if someone has immunity and you want to know if it was vaccine induced or if they earned their immunity naturally.

Unfortunately, you typically can’t, especially as most vaccines mimic having a natural infection.

In a few situations, if a vaccine targets a very specific part of a virus or bacteria, it may be able possible to tell the difference between vaccine-induced and natural immunity though.

anti-HBs is positive with natural infections and vaccination, but only anti-HBc is positive after a natural infection.

The hepatitis B vaccine, for example, is derived from HBsAg particles, so won’t induce antibodies against hepatitis B core antigen or other hepatitis B proteins.

Most other vaccines, like MMR and Varicella, aren’t so specific. Titers might just show that you are immune, although titer tests aren’t always sensitive enough to pick up vaccine-induced immunity. That’s why, expect for a few high risk situations, titer testing isn’t usually recommended.

More on Titers for Vaccine vs Natural Immunity

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