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.
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.
If most adults aren’t immune because they haven’t been vaccinated or don’t get boosters, then since we aren’t seeing that many outbreaks, herd immunity itself must be a myth.
The thing is though, adults were either born in the pre-vaccine era and likely earned their natural immunity or were born in the vaccine era and are vaccinated and immune.
It is also important to understand that herd immunity is disease specific, so when we talk about herd immunity for measles, it doesn’t matter if everyone has herd immunity levels of protection against hepatitis A or Hib.
And adults do get a few boosters and some vaccines that are only recommended for adults, including the shingles vaccine.
In addition, some vaccines, like Hib and Prevnar, have indirect effects, protecting adults even though they aren’t vaccinated, because vaccinated kids are less likely to become infectious.
But back to the original question, how many adults are up to date on their immunizations?
“While modest gains occurred in vaccination coverage for pneumococcal, Tdap, hepatitis A (persons with chronic liver conditions), herpes zoster, and HPV vaccination, coverage did not improve for other vaccinations and many adults remained unvaccinated with recommended vaccines. “
Vaccination Coverage Among Adults in the United States, National Health Interview Survey, 2016
While most adults are immune to what were once common childhood diseases, like measles and mumps, because they were either vaccinated or had the disease naturally, many could do better with newer vaccines that weren’t available when they were kids.
“Existing evidence on the safety and effectiveness of MMR vaccine supports current policies of mass immunisation aimed at global measles eradication and in order to reduce morbidity and mortality associated with mumps and rubella.”
Cochrane Systematic Review on Vaccines for measles, mumps and rubella in children
Let’s see if you still are after we get all of your questions about the measles vaccine answered…
How long has the measles vaccine been around? The very first measles vaccine was licensed by John Enders in 1963. An improved measles vaccine was developed by Maurice Hilleman and licensed in 1968, and that is the measles vaccine that we still use today, at least in the United States. It was combined into the MMR vaccine in 1971.
How effective is the measles vaccine? A single dose of the measles vaccine is about 93% effective at preventing a measles infection. Two doses (the second dose was added to the routine immunization schedule in 1994) are up to 97% effective. That’s why almost all of the people who get measles in an outbreak are unvaccinated.
How long does immunity from the measles vaccine last? Immunity from the measles vaccine is thought to be life-long. It is important to understand that the second dose isn’t a booster dose, but is instead for those few folks who don’t respond to the first dose.
Who should get the measles vaccine? Everyone without a true medical contraindication should get the measles vaccine (MMR), with the first dose at 12-15 months and a second dose at 4-6 years.
Can my kids get their measles vaccine early? An advanced immunization schedule is available for kids in an outbreak or if they will be traveling out of the country. The first dose can be given as early as age 6-months, but is repeated when the child is 12 months because of concerns of interference with maternal antibodies. The official second dose can be given early too, as early as 4 weeks after the first dose, as long as the child is at least 12 months old.
Do I need a booster dose of the measles vaccine? People who are fully immunized do not need a booster dose of the MMR vaccine, but it is important to understand whether or not you are really fully immunized to see if you need a second dose. Some adults who are not high risk are considered fully vaccinated with only one dose, while others should have two doses. Are you at high risk to get measles? Do you travel, live in an area where there are measles outbreaks, go to college, or work as a health care professional?
Should I check my measles titers? In general, it is not necessary to check your titers for measles. If you haven’t had two doses of the MMR vaccine, then get a second dose. If you have had two doses of the MMR vaccine, then you are considered protected. Keep in mind that there is no recommendation to get a third dose of MMR for measles protection, although it is sometimes recommended for mumps protection during a mumps outbreak.
If my child gets a rash after getting his MMR, does that mean that he has measles? No. This is a common, very mild vaccine reaction and not a sign of measles.
Can the measles vaccine cause seizures? The MMR vaccine can cause febrile seizures. It is important to remember that without other risk factors, kids who develop febrile seizures after a vaccine are at the same small risk for developing epilepsy as other kids. And know that vaccines aren’t the only cause of febrile seizures. Vaccine-preventable diseases can cause both febrile seizures and more serious non-febrile seizures.
Why do people think that that the measles vaccine is associated with autism? It is well known that this idea originated with Andrew Wakefield, but the real question should be why do some people still think that vaccines are associated with autism after so much evidence has said that they aren’t?
What are the risks of the measles vaccine? Like other vaccines, the MMR vaccine has mild risks or side effects, including fever, rash, and soreness at the injection site. Some more moderate reactions that can rarely occur include febrile seizures, joint pain, and a temporary low platelet count. More serious reactions are even rarer, but can include deafness, long-term seizures, coma, or lowered consciousness, brain damage, and life-threatening allergic reactions.
When did they take mercury out of the measles vaccine? Measles vaccines, including the MMR, have never, ever contained mercury or thimerosal.
Why do we still have outbreaks if we have had a measles vaccine since 1963? In the United States, although the endemic spread of measles was declared eliminated in 2000, many cases are still imported from other countries. As measles cases increase around the world, that is translating to an increase in outbreaks here. Even though overall vaccination rates are good, because there are many pockets of susceptible people in areas that don’t vaccinate their kids, they get hit with outbreaks.
Can we eradicate measles? Because measles is so contagious, the vaccine does have failures, and some folks still don’t get vaccinated, there is some doubt that we can eradicate measles without a better vaccine. That doesn’t mean that the current measles vaccines can’t prevent outbreaks though…
Are you ready to get your kids their MMR vaccine so that they are vaccinated and protected against measles, mumps, and rubella?
“…California patients were genotyped; all were measles genotype B3, which has caused a large outbreak recently in the Philippines…”
Measles Outbreak — California, Dec 2014–Feb 2015
It wasn’t a vaccine strain.
For example, during 2011, 222 cases of measles and 17 outbreaks were reported in the United States, with most cases originating from just five countries (France, Italy, Romania, Spain, and Germany). Six different genotypes were identified, including B3, D4, G3, D8, H1, and D9. No vaccine strains…
And no, it doesn’t matter that the vaccine strain of measles, genotype A, differs from all of the wild strains of measles we see in the outbreaks.
“Vaccine induced immunity protects against all virus strains. Measles is considered a monotypic virus despite the genetic variations.”
Factsheet about measles
Unlike the flu, HPV, and pneumococcal bacteria, in which vaccines only protect against different serotypes, in the case of measles, the genotype simply helps us figure out where the measles case came from.
But if it isn’t the vaccine strain, then why do they that is it important to rapidly identify wild strains vs vaccine strains?
“During measles outbreaks, it is important to be able to rapidly distinguish between measles cases and vaccine reactions to avoid unnecessary outbreak response measures such as case isolation and contact investigations.”
Roy et al on Rapid Identification of Measles Virus Vaccine Genotype by Real-Time PCR
That’s easy to answer.
Outbreaks typically trigger a lot of folks to get vaccinated. While that’s great, one possible problem is that some of those folks might develop a fever and/or rash after their MMR vaccine. So it is important to quickly figure out whether they are part of the outbreak and have a wild strain (maybe they were exposed before their vaccine could start to work) or are having a common, mild vaccine reaction.
But couldn’t they have vaccine-associated measles if they have a rash and fever and a vaccine strain? Theoretically, but then they would likely have true measles symptoms. And even in these rare case reports, the children didn’t spread the measles to anyone else.
So why are you waiting to know the genotype of the measles strain causing the outbreak in your area? Hopefully, it isn’t to help you decide whether or not to vaccinate and protect your kids. While it is interesting to know where the outbreak originated, you can bet that it isn’t a vaccine strain.