Tag: antigens

Are the Tdap and DTaP Vaccines the Same Thing?

You have probably already figured out the Tdap and DTaP aren’t the same vaccine, after all, if they were, why would they have different names, right?

Are the Tdap and DTaP Vaccines the Same Thing?

I bet you don’t know the difference between the two vaccines though.

Yes, they both are both combination vaccines that protect against diphtheria, tetanus, and pertussis.

The difference is that one (DTaP) is used as the primary series for infants and younger children (age 6 years and under) and the other (Tdap) is given to older children (age 7 years and above), teens, and adults.

Okay, that’s not the only difference.

The DTaP vaccine actually contains more diphtheria and pertussis antigens than Tdap, which is why it has the capital “D” and “P” in its name. The amount of tetanus toxoid antigens are about the same in both vaccines.

So Tdap contains the same amount of tetanus toxoid, plus a reduced amount of diphtheria and acellular pertussis antigens, as compared to DTaP.

While you would think that older children and adults would get the vaccine with the higher amount of antigens, since they are bigger, that’s not how this works. Vaccines typically start working at the injection site, so body size isn’t a key factor in determining the amount of ingredients.

As a booster dose of vaccine, the lower amount of antigens works just fine and helps reduce the risk of side effects from repeated doses that you might get with higher antigen counts.

More on Tdap vs DTaP

Where are the Saline Placebos?

Remember when anti-vaccine folks used to say that there were no double-blind, placebo-controlled randomized clinical trials for vaccines?

What happened once they realized that there actually were?

They moved the goal posts…

Where are the Saline Placebos?

Okay, they said.

So you have done double-blind, placebo-controlled randomized clinical trials when testing vaccines, but what placebo did you use?

Was it a pure saline placebo?

“Placebo Control – A comparator in a vaccine trial that does not include the antigen under study. In studies of monovalent vaccines this may be an inert placebo (e.g. saline solution or the vehicle of the vaccine), or an antigenically different vaccine. In combined vaccines, this may be a control arm in which the component of the vaccine being studied is lacking.”

WHO on the Guidelines on clinical evaluation of vaccines: regulatory expectations

Although no guidelines actually call for using a pure saline placebo, that’s all anti-vaccine folks will accept these days.

Why?

That’s there MO – or method of operation.

When one theory or myth gets squashed – they move to another.

They move the goalposts.

It doesn’t matter that there are often ethical and logistical problems with using pure saline placebos, that’s all they want to hear about it.

That they wouldn’t be satisfied and start vaccinating their kids if all vaccine studies started to use saline placebos should be evident when you consider that many vaccine studies have already used saline placebos!

There are many more vaccine studies that have used saline placebos and like other vaccine studies, have found vaccines to be safe and effective.

But how do you know that they used a real saline placebo and not some kind of saline solution with other stuff in it?

If it isn’t clear to you in the methods section of the study, go to the source – the original clinical trials record and it will be listed there.

What are you going to be worried about now?

More on Saline Placebos

What Is a Vaccine?

You know what a vaccine is, right?

The word vaccine comes from the vaccinia virus that was in the original smallpox vaccine.
The word vaccine comes from the vaccinia virus that was in the original smallpox vaccine.

The flu shot you get each year is a vaccine.

Vaccine: A product that stimulates a person’s immune system to produce immunity to a specific disease, protecting the person from that disease. Vaccines are usually administered through needle injections, but can also be administered by mouth or sprayed into the nose.

Immunization: The Basics

The smallpox shot that Edward Jenner developed was a vaccine.

Vaccine Definitions

While that is an easy enough definition to understand, that there are many different types of vaccines does make it a little more complicated.

There are:

  • Live-attenuated vaccines – made from a weakened or attenuated form of a virus or bacteria
  • Inactivated vaccines – made from a killed form of virus or bacteria
  • Subunit, recombinant, polysaccharide, and conjugate vaccines – made from only specific pieces of a virus or bacteria
  • Toxoid vaccines – made to target a toxin that a bacteria makes and not the bacteria itself

And of course all of these types of vaccines work to produce immunity to specific diseases – vaccination.

Immunization: A process by which a person becomes protected against a disease through vaccination. This term is often used interchangeably with vaccination or inoculation.

Immunization: The Basics

What other definitions are important to know when you talk about vaccines?

  • active immunity – immunity that you get from having a disease (natural immunity) or getting a vaccine and making antibodies
  • adjuvant – a substance that helps boost your body’s immune response to a vaccine so that you can use a minimum amount of antigen, reducing side effects
  • antibodies – protective proteins that you make against antigens
  • antigens – specific substances (can be part of a virus or bacteria) that trigger an immune response
  • attenuation – a virus or bacteria that is made less potent, so that it can produce an immune response without causing disease
  • elimination – getting rid of a disease in a specific area
  • endemic – the baseline level of disease in an area
  • eradication – getting rid of a disease everywhere (smallpox)
  • epidemic – an increase in the number of cases of a disease over a large geographic area
  • herd immunity – when enough people in a community are protected and have immunity, so that disease is unlikely to spread
  • immunity – protection against a disease
  • incubation period – how long it takes to develop symptoms after you are exposed to a disease
  • outbreak – an increase in the number of cases of a disease over a small geographic area
  • pandemic – an increase in the number of cases of a disease over several countries or continents
  • passive immunity – temporary immunity that you get after being given antibodies, either via a shot of immunoglobulin or a mother’s antibodies are transferred to her baby through her placenta
  • placebo – classically defined as “a comparator in a vaccine trial that does not include the antigen under study”
  • quarantine – isolating someone so that they don’t get others sick
  • titer – an antibody count that can often be used to predict immunity

Got all of that?

So what about variolation, the process that was used before Jenner developed his smallpox vaccine? Was that also a vaccine?

It did produce immunity to smallpox, which is the basic definition of a vaccine, but still, variolation is typically concerned an immunization technique and not a vaccine.

More on Vaccine Definitions

What is Corvelva?

Have you heard of Corvelva?

People are dying of measles in Italy and groups like Corvela are pushing anti-vaccine propaganda to further scare folks away from vaccinating and protecting their bambini.
People are dying of measles in Italy and groups like Corvela are pushing anti-vaccine propaganda to further scare folks away from vaccinating and protecting their bambini.

Probably not, but they are getting some attention in the anti-vaccine world because they think that they have uncovered a Vaccingate!

What is Corvelva?

Specifically, they analyzed the Infranix Hexa vaccine, and instead of finding DTaP-IPV-HepB/Hib antigens, they think that they found “65 signs of chemical contaminants of which only 35% is known” and “7 chemical toxins.”

Should you be worried?

“Coming back to the two basic principles that have been our topic on this analysis path, we reaffirm what we have said in the recent interview on the scientific journal Nature: we are inquiring the vaccines efficacy and safety and we can’t quite understand how it is possible to claim that this vaccine is even able to generate the 6 protective antibodies – reason why it is designed for – and furthermore to understand how this cluster made of 6 neurotoxic antigens bound together can be claimed as not toxic for newborns.”

Corvelva on Vaccingate: Initial results on Infanrix Hexa chemical composition

Although they might not understand it, Infranix Hexa has been proven to be safe and has been proven to work. You can read study after study in well respected peer reviewed journals that say so.

The Corvela Vaccingate “study” wasn’t published in a well respected peer reviewed journal. It wasn’t even published in one of the typical bottom-feeder, pay-to-publish journals that anti-vaccine researchers frequently use.

What Corvela did was more like a very poorly done science fair project by a kid who got too much help from his anti-vaccine parents.

Using the Surface Activated Chemical Ionization-Electrospray-NIST Bayesian model database search (SANIST) platform is pretty cool, to be sure. But why are we supposed to believe that their method would actually deconstruct the Infanrix Hexa vaccine? Because that’s why they were trying to do – separate out all of the combined vaccine ingredients so that they could be detected by SANIST. The combined vaccine ingredients, including one of which is an emulsifier that keeps the ingredients from separating, in a 6-in-1 combination vaccine.

So what’s more likely? That the unnamed ‘scientists’ at Corvela, which is basically an anti-vaccine website in Italy, did the experiment wrong or that the Infanrix Hexa vaccine, which is used in countries all over the world, doesn’t contain any of the antigens that it is supposed to contain?

A previous study on vaccines that they also have posted to their website and to an open peer review site was not approved, getting a lot of criticism.

Have you figured out what Corvela stands for yet?

It’s Italian for covfefe.

More on Corvelva

What Is a Hexavalent Vaccine?

Most folks know that we have combination vaccines that help reduce the number of injections that kids have to get at one visit.

You might not think of it as a combination vaccine, but one of the first, DPT, simply combines protection against diphtheria, pertussis, and tetanus into one shot.

Of course, we have come a long way since the days when DPT and MMR were considered combination vaccines.

Wait, why aren’t they considered combination vaccines anymore?

It’s not part of any conspiracy. It’s simply because you can’t get their individual components separately anymore. There is no measles or rubella shots anymore. Just the MMR. There is no tetanus shot.

Combination Vaccines

Not surprisingly, it is now becoming routine for kids to get combination vaccines instead of separate shots.

That’s because while the great majority of us want our kids vaccinated and protected, few enjoy shots and needles.

“The use of licensed combination vaccines is preferred over separate injection of their equivalent component vaccines.”

AAP on Combination Vaccines for Childhood Immunization

Does this mean more vaccines at one visit?

Nope.

“So, at a doctor’s visit, your child may only get two or three shots to protect him from five diseases, instead of five individual shots. Fewer shots may mean less pain for your child and less stress for you.”

CDC on Combination Vaccines

It just means fewer injections.

Combination vaccines combine the vaccines that you are already getting into one injection.

What Is a Hexavalent Vaccine?

And they might get even fewer with the latest hexavalent vaccines (six-in-one).

This is the next step up from our current pentavelent vaccines (five-in-one), like Pediarix (combines DTaP, Hep B, and IPV) and Pentacel (combines DTaP, IPV, and Hib).

The hexavalent vaccines combine protection against diphtheria, tetanus, acellular pertussis, Haemophilus influenzae type B, poliovirus and hepatitis B (DTaP-Hib-IPV-HepB) into one injection.

Sounds good, right?

Although not approved in the United States, hexavalent vaccines, including Infanrix Hexa have been used in many other countries since 2000! Another, Hexavac was withdrawn from the market because of issues with waning hepatitis B antibody titers (kids had levels that were still protective, but were on the low side).

When will get a hexavalent vaccine in the United States?

Obviously, the early problems with Hexavac kept us from getting a hexavalent vaccine, at least before the next generation of vaccines was developed.

Hexavalent vaccines are widely available in most parents of the world.
Hexavalent vaccines are widely available in most parents of the world.

Two new hexavalent vaccines, Vaxelis and Hexyon, have recently been licensed in Europe, after many studies showed that they worked and were safe when given with all of the other vaccines on the schedule, including Prevnar, rotavirus, Men C, and MMRV.

And one of these might soon be coming to the United States.

Vaxelis

V419 (Vaxelis), which was developed in collaboration between Merck and Sanofi Pasteur, has been under review by the FDA since 2014 has already received a Complete Response Letter that was “deemed complete and acceptable for review.”

And it was approved by the FDA on December 21, 2018.

Remember, that could mean just two shots at infant well check ups, but continued protection against eight vaccine-preventable diseases, as they get a hexavalent vaccine, Prevnar and the rotavirus vaccine!

It may be at least another year before Vaxelis makes it way to your pediatrician’s office though.

More on the Hexavalent Vaccine

Why Do Some Vaccines Need Boosters?

Vaccines work.

They aren’t perfect though, which is why some vaccines need booster doses to help them provide long lasting protection.

Why Do Some Vaccines Need Boosters?

To be clear, just because you get more than one dose of a vaccine, that doesn’t make it a booster dose.

For example, infants get multiple doses of the DTaP, polio, Hib, hepatitis B, Prevnar, and rotavirus vaccines, but those are part of the primary series for those vaccines. They aren’t boosters.

“A “classical” prime-boost immunization schedule is, thus, to allow 4 to 6 months to elapse between priming and booster doses, hence the generic “0-1-6 month” (prime-prime-boost) schedule. Secondary antigen exposure thus results in the production of higher-affinity antibodies than primary responses.”

Plotkin’s Vaccines (Seventh Edition)

Getting the booster shot in a vaccine series is important to get full protection.
Getting the booster dose in a vaccine series is important to get full protection.

Classic booster doses are the:

But why do we need these booster doses?

While one or more doses of the primary series of the vaccine leads to the production of plasma cells and protective antibodies, the booster dose then causes a secondary immune response and the production of more long-lived plasma cells. That’s how we get higher levels of protective antibodies that will last longer.

Which Vaccines Don’t Need Boosters?

In general, live vaccines don’t need booster doses.

So why do we get a second dose of MMR?

This isn’t a classic booster dose. It protects the small percentage of people who don’t respond to the first dose.

Some folks may need a booster dose of the MMR vaccine in certain circumstances though, specifically if they are caught up in a mumps outbreak.

What to Know About Vaccine Booster Doses

Some vaccines need booster doses to help you get full protection. Don’t skip them.

More on Vaccine Booster Doses

Aren’t Vaccines Made for Adults?

Have you ever heard someone bring up the argument that vaccines are made for adults, so kids shouldn’t be getting the same dosage?

If they do, you should understand right away that they don’t really understand how vaccines work.

And that they really don’t understand immunology either, for that matter.

Are Vaccines Made for Adults?

To be fair, some vaccines are made just for adults. In fact, some, like the shingles vaccines and high-dose flu shot (has four times the amount of antigen in the regular flu shot) are only for seniors.

Other vaccines, like the rotavirus vaccine, are made just for kids.

And a few vaccines come in different forms depending on your age.

For example, younger kids get the DTaP vaccine, while older kids and adults get a Tdap vaccine. They both protect against the same three diseases (diphtheria, tetanus, and pertussis), but they contain different amounts of antigens. In this case, the Tdap vaccine actually contains 3-5 times less of the diphtheria component as the DTaP vaccine. That’s because before they lowered it, repeated dosing of the original Td vaccine every ten years led to worsening local reactions in some people.

The hepatitis B and hepatitis A vaccines are also available in different formulations for kids and adults, with adults getting twice the amount of antigens.

Most other vaccines though, come in the same form for both kids and adults, including the MMR vaccine and vaccines that protect us against HPV, chicken pox, polio, meningococcal disease, and pneumococcal disease, etc.

Are Vaccines Calibrated by Weight or Age?

Why does this question even come up?

Science event in Washington, D.C. reminding folks that Vaccines Work.
Pediatricians at the March for Science event in Washington, D.C. reminded folks that Vaccines Work. We shouldn’t forget that others also need a reminder of how they work.

It’s because some folks push the myth that infants are getting too high a dose of vaccines, since in most cases, older kids and adults get the very same dose.

They don’t though.

Does that mean that those older kids and adults are getting too low a dose then?

Nope.

You see, vaccines aren’t like antibiotics or other medications. They aren’t typically dosed based on your weight or age and don’t have to build up to a steady state in your blood stream.

That’s right, for most vaccines, it doesn’t matter if your child weighs 8 pounds or 80 pounds.

Why not?

Because the antigens in the vaccine don’t have to travel all around your child’s body in order for them to work!

Understanding the Immune Response to a Vaccine

Instead, the small amount of antigens in a vaccine simply get the vaccine response started near where the vaccine was given, whether that is in their arm or leg (shot), nose (nasal), or small intestine (oral).

“B cells are essentially activated in the lymph nodes draining the injection site.”

Claire-Anne Siegrist on Vaccine Immunology

Antigen-presenting cells (APCs) then take up the antigens and migrate towards a nearby lymph node. It is at these lymph nodes that the APCs activate other cells, including:

  • antigen-specific helper T cells
  • killer T cells
  • B cells

The activated T and B cells then go to work, with many B cells becoming plasma cells, and some T and B cells transforming into memory cells.

This illustration from the NIH and National Library of Medicine helps explain how vaccines work.
This illustration from the NIH and National Library of Medicine explains how vaccines work.

Next, within days to weeks of getting vaccinated, the plasma cells begin producing protective antibodies, which are released into our bloodstreams.

The same thing happens if you are exposed to a disease naturally, which is why it is silly to think that a vaccine could weaken or overwhelm your immune system.

The big difference about getting exposed to a disease naturally vs getting a vaccine? With the vaccine, you don’t have to actually have the the symptoms of the disease or any of its complications to get immunity. In other words, you don’t have to earn your immunity.

What to Know About Vaccine Dosage Myths

The dose of vaccines for kids and adults is not calibrated by weight or age because the immune reaction that helps antibodies travel all through your body starts locally, near where the vaccine was given.

More on Vaccine Dosage Myths