Tag: immune response

How is the Immunization Schedule Developed?

For some reason, there still seems to be a lot of confusion out there about just how the immunization schedule is developed.

Jay Gordon wonders about the research used to set the current immunization schedule...
ICYMI – Jay Gordon was Jenny McCarthy‘s pediatrician.

Who decides which vaccines we give and get?

How do they make that decision?

History of Immunization Schedule Development

While the current immunization schedule is developed by the CDC based on recommendations of the Advisory Committee on Immunization Practices (ACIP), that’s not how it was always done.

It has just been since 1995 that we have had this single, simple vaccine schedule and format.

The first unified immunization schedule was developed in 1995.
The first unified immunization schedule was developed in 1995.

Before that, we had separate vaccine schedules from the:

Even earlier, we had recommendations and schedules from

  • WHO Expanded Programme on Immunization (EPI)
  • AAP’s Special Committee on Prophylactic Procedures Against Communicable Diseases – from its start in the early 1930s, it evolved into today’s Committee on Control of Infectious Diseases
  • American Public Health Association Subcommittee on Communicable Disease Control

Differences in those schedules, which could lead to confusion, lead experts to create a simpler, unified schedule.

Well, at least in the United States. Of course, other countries still set their own schedules…

The Science Behind Setting the Immunization Schedule

Now that you know who sets the immunization, you are probably wondering how they set the immunization schedule.

To truly understand how the immunization schedule gets set up, it is best to go to an ACIP meeting when they make those decisions.

Can’t make it to Atlanta for one of the ACIP meetings?

You can watch them online!

Thoughtful discussions on setting the immunization schedule at ACIP.
Thoughtful discussions on setting the immunization schedule at ACIP.

Past ACIP meetings, agendas, minutes, slides, and videos, are archived online too.

Reading the minutes from the third meeting of the Advisory Committee on Immunization Practices on November 19-20, 1964 shows how they work, looking at data to make decisions about our vaccines and set the immunization schedule.
Reading the minutes from the third meeting of the Advisory Committee on Immunization Practices on November 19-20, 1964 shows how they work, looking at data to make decisions about our vaccines and set the immunization schedule.

Review them and you will get a very good idea of how the immunization schedule gets set up.

The first flu vaccine was developed in 1945.

ACIP basically told folks to go back to the drawing board and make a better flu vaccine at this 1966 meeting.
ACIP basically told folks to go back to the drawing board and make a better flu vaccine at this 1966 meeting.

Did you ever wonder why it took so long to get it on the immunization schedule?

Why was the primary series of polio vaccines made up of three doses?

At the Advisory Committee on Immunization Practices meeting on May 24-26, 1967 they discussed polio vaccine scheduling.
At the Advisory Committee on Immunization Practices meeting on May 24-26, 1967 they discussed polio vaccine scheduling.

Hopefully you are starting to understand how this works…

And no, all of this work doesn’t get done over a couple of days a few times a year. ACIP members belong to workgroups which focus on specific vaccines and they gather, analyze, and prepare information and research about those vaccines throughout the year.

It is at the ACIP meetings where the workgroup findings are presented.

“Development of vaccine schedules is based on a large body of basic sciences and epidemiologic research. There is constant review of evidence, adverse events, and epidemiology by a panel of experts.”

Shetty et al on Rationale for the Immunization Schedule: Why Is It the Way It Is?

And yes, among that body of research are studies of vaccines tested together, vaccines tested with placebos, vaccines tested vs unvaccinated kids, vaccines tested for long periods of time, and studies looking at risk factors to make sure vaccines don’t cause long-term health problems.

It’s a very thorough process!

And that’s why the great majority of folks understand that following the immunization schedule is the best way to keep their kids protected from vaccine-preventable diseases.

Vaccines are safe, with few risks, and are obviously necessary.

What’s not safe? What hasn’t been well studied?

Following a non-standard, parent-selected, delayed protection vaccine schedule.

Thinking that an individualized approach is better doesn't trump the 55 years of ACIP meetings that went into setting the current immunization schedule...
Thinking that an individualized approach is better doesn’t trump the 55 years of ACIP meetings that went into setting the current immunization schedule…

Studies have actually shown that delaying or skipping vaccines offers no benefits and actually puts kids at extra risk.

It puts the rest of us at risk too.

More on Setting the Immunization Schedule

Did Dr. Bob Uncover a CDC Plot to Give Adult Flu Shots to Babies?

Have you heard the news?

Uh, the ACIP can't request a license for a vaccine...
Uh, the ACIP can’t request a license for a vaccine…

Dr. Bob and his new podcasting side kick think that the “CDC wants the FDA to approve adult doses of the flu vaccine for babies, because the normal half-doses approved for babies don’t work well enough.”

Did Dr. Bob Uncover a CDC Plot to Give Adult Flu Shots to Babies?

This is likely going to surprise Dr. Bob, but many infants already get the same dose of flu vaccine as adults.

Both FluLaval and Fluarix are given at the same 0.5ml dose, containing 15 µg of HA per vaccine virus, to infants, older children, and adults.

Fluzone, on the other hand, is still given at a 0.25ml dose, containing 7.5 µg of HA per vaccine virus, to children between the ages of 6 months to three years, and a larger 0.5ml dose to older kids and adults.

Why the differences?

“In a randomized trial comparing immunogenicity and safety of 0.5 mL FluLaval Quadrivalent with 0.25 mL Fluzone Quadrivalent, safety and reactogenicity were similar between the two vaccines.”

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season

Because they are just as safe at the lower doses and might actually work better.

Then why did we ever use a lower dose for infants?

That recommendation was based on the older, whole-virus version of the flu shot, which did cause more side effects for infants when given at a full dose. We now use split-virus flu shots that don’t have this problem.

And now, the manufacturer of Fluzone has done a study, and not surprisingly, they have also found that “safety profile of a 0.5 ml (full-dose) is similar to 0.25 ml (half-dose) and may be more immunogenic.”

So they are submitting a BLA to the FDA for the use of the 0.5ml dose of their flu vaccine for infants.

What about the idea of an “adult dose of mercury” for infants?

Over 80% of flu vaccines were thimerosal free this year. You almost have to go out of your way to get your kids a flu vaccine with thimerosal, so no, this won’t mean an “adult dose of mercury” for your infant.

Most importantly though, if you understand how vaccines work, you know that the dose of vaccines for kids and adults is not calibrated by weight or age, so none of this really matters. The immune reaction that helps antibodies travel all through your body starts locally, near where the vaccine was given, so a 20-pound infant and a 200-pound adult can get the same dose of flu shot and both can be protected.

More on Dr. Bob’s CDC Plot to Give Adult Flu Shots to Babies

Is There a Grace Period for Getting Vaccines?

You know about the standard immunization schedule.

Looking at the latest immunization schedule from the CDC and AAP, it should be clear that kids don't get 69 vaccines.
What happens if you get a vaccine a few days too early?

You may even know about the minimum ages or minimum intervals between vaccines, but what happens if your child gets a vaccine just a few days early?

Is There a Grace Period for Getting Vaccines?

Fortunately, in most cases, getting a vaccine just a little early isn’t going to mean that the vaccine dose has to be repeated.

“Doses administered too close together or at too young an age can lead to a suboptimal immune response. However, administering a dose a few days earlier than the minimum interval or age is unlikely to have a substantially negative effect on the immune response to that dose. Known as the “grace period”, vaccine doses administered ≤4 days before the minimum interval or age are considered valid; however, local or state mandates might supersede this 4-day guideline.”

General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP)

That’s because the Advisory Committee on Immunization Practices (ACIP) allows a 4-day grace period for most vaccines. So if your child got their vaccines 3 or 4 days before their 1st birthday, instead of on or after turning 12 months old, they would still count!

It is important to keep in mind that:

  • day 1 is the day before the day that marks the minimum age or minimum interval for a vaccine.
  • the grace period doesn’t apply to the rabies vaccine
  • if a vaccine is given 5 or more days too early, beyond the grace period, then the interval to the next dose starts from the day that invalid dose was given. For example, if the second dose of Hib is given two weeks after the first dose (instead of the minimum 4 weeks), then you don’t repeat this invalid dose in two weeks (four weeks from the first dose), but instead wait an additional four weeks from the invalid second dose
  • you can’t usually add the grace period to an accelerated schedule
  • live vaccines must be given at least 28 days apart if they are not given at the same time and the grace period can not be used to shorten this interval

Most importantly, in place since 2002, the grace period protects kids from having to repeat vaccines because of minor vaccine scheduling errors.

More on the Vaccine Grace Period

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