“We learn about a vaccine’s safety during clinical trials before it is licensed, and monitor it continually as millions of doses are administered after it is licensed. We also know there is not a plausible biologic reason to believe vaccines would cause any serious long-term effects. Based on more than 50 years of experience with vaccines, we can say that the likelihood that a vaccine will cause unanticipated long-term problems is extremely low.”
Parents’ Guide to Childhood Immunizations
These long term studies on vaccine safety have looked at:
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.
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.
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!
Year-round influenza immunisation during pregnancy in Nepal: a phase 4, randomised, placebo-controlled trial – “The control group will be placebo (saline injection). The justification for the use of a placebo injection in this trial is as follows: There is only one trial (Bangladesh) that demonstrates efficacy of influenza vaccination in pregnancy on perinatal outcomes and respiratory morbidity in early infancy. One of the issues with that study is that it was not placebo controlled. The “control” in that study was adult pneumococcal vaccine. It could be that the Bangladesh study underestimated the impact of influenza vaccine because the mothers and infants receive some indirect protection from the pneumococcal vaccine. In addition, influenza vaccine is not part of national policy or recommendations in Nepal at the current time and Ministry of Health officials are very interested in the results of our study as they consider their immunization program expansion over the next few years.”
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.