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.
“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?
Thimerosal was taken out of most childhood vaccines in 2001, only remaining in muti-dose vials of flu vaccines, which could easily be avoided, as a good supply of thimersosal-free flu vaccine has been available for many years.
“Thimerosal is a mercury-based preservative that has been used for decades in the United States in multi-dose vials (vials containing more than one dose) of medicines and vaccines. There is no evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site. However, in July 1999, the Public Health Service agencies, the American Academy of Pediatrics, and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure.”
CDC on Thimerosal in Vaccines
For some reason, that hasn’t kept some parents from still being concerned about mercury in vaccines.
Does Pentacel Contain Mercury?
Pentacel is vaccine that combines the diphtheria and tetanus toxoids and acellular pertussis adsorbed, inactivated poliovirus and Haemophilus b conjugate (tetanus toxoid conjugate) vaccines (DTaP-IPV/Hib) into one shot.
It is routinely given to children as a four dose series, when they are 2, 4, 6, and 15 to 18 months old.
Like most other vaccines given to children, Pentacel is thimerosal-free.
It is very easy to get confused when thinking or talking about chicken pox and shingles.
Remembering a few things should help though:
shingles (herpes zoster) is a reactivation of chicken pox (varicella zoster) – since they are caused by the same virus, you had to have been exposed to the chicken pox virus (varicella zoster virus) to later get shingles
exposure to the chicken pox virus can come from a natural chicken pox infection or from getting vaccinated against chicken pox, as it is a live, attenuated vaccine (Varivax)
So no, getting the chicken pox vaccine will not prevent you from later getting shingles. The shingles vaccine is a different vaccine that is given to seniors to help prevent them from getting shingles.
Can You Still Get Shingles After Having the Chicken Pox Vaccine?
Have you ever heard of a child vaccinated against chicken pox getting shingles? It can happen. It’s not a vaccine injury.
Remember that you can get shingles at any age – it is not just a disease of senior citizens. Even preschools or teens can get shingles, with the risk increasing with age.
Although the chicken pox vaccine won’t prevent you from getting shingles, it does work well to prevent you from getting chicken pox.
And it is thought that getting vaccinated and protected against chicken pox will decrease your risk of later getting shingles, even before you ever get the shingles vaccine.
“In the early post-varicella vaccination period, incidence rates of medically attended herpes zoster did not increase for the overall population and decreased moderately for children 9 years and younger, the age group targeted for varicella vaccination.”
Tanuseputro et al on Population-based incidence of herpes zoster after introduction of a publicly funded varicella vaccination program