Chapter 51: Immunizations – Vaccines & Clinical Guidelines

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Welcome back to the Deep Dive.

Today, we're jumping right into immunizations.

You know, it's often called one of the greatest public health achievements ever.

It really is.

And we see the proof, right?

Childhood coverage for things like MMR, DTaP, it's often over 95 % in schools.

Which has led to those record low cases of polio, measles, things we barely see now, thankfully.

But that success can actually be a bit deceptive for advanced practice students, can't it?

Oh, absolutely.

It can lead to a kind of complacency.

So our mission today isn't just the basics you already know, we need to dig deeper.

Right.

We're focusing on the tricky stuff, the pharmacology, the special considerations, the complex schedules, the things you need to master as a clinician.

Exactly.

Like understanding the different pneumococcal vaccines or knowing precisely when high dose steroids mean you have to hold off on a live vaccine.

Those nuances.

Okay, so here's the reality check.

While childhood rates are great.

Adult and adolescent coverage.

It's worryingly low.

We're talking maybe 33 % to 70 % for flu or pneumococcus in adults under 65.

Wow, that low.

Yeah.

And think about this, pneumonia and influenza,

still the eighth leading cause of death in the US.

So that gap in adult vaccination, it translates directly into preventable deaths.

And that's before we even factor in growing vaccine hesitancy.

Which the WHO calls a global health threat.

So your role, your assessment and intervention is absolutely critical.

Okay, that definitely sets the stage.

So our plan, first, we'll distinguish the two main types of immunization.

Active versus passive.

Got it.

Then we'll tackle special populations like immunosuppressed patients, preterm infants.

Oracial areas.

And finally, we'll break down some key specific vaccines.

Pneumococcal, flu, Tdap, and those really critical contraindications.

Sound good.

Sounds like a plan.

Let's start with those core concepts.

Active versus passive, okay.

Active immunization, that's the one we think of most often.

Give a vaccine,

live, attenuated, maybe inactivated.

Right, you're giving an antigen.

And the goal is to stimulate the person's own immune system to build defenses for the future.

Like a practice run for the real infection, but safe.

Exactly.

It mimics natural infection.

Ideally giving long -lasting, sometimes lifelong, protection.

Passive immunization then is different.

It's more immediate.

It's borrowed immunity.

You're giving preformed antibodies directly.

Think of it as immediate, but temporary, protection.

So you'd use that when someone's already been exposed or exposure is like right now.

Precisely.

Or if the person is immunodeficient and can't make their own antibodies effectively.

Or just when there isn't time for an active vaccine to work.

Like with rabies, post -exposure maybe.

Or hepatitis B immune globulin for a newborn whose mom is positive.

Perfect examples.

You need protection now.

Okay, thinking about the vaccines themselves, they're not just the antigen, right?

There's other stuff in there.

Right.

Pharmacologically, you've got the active part, the antigen, but also suspending fluids, maybe preservatives, stabilizers, sometimes antibiotics,

and often adjuvants.

Adjuvants.

What's their role again?

They're basically immune boosters.

They help provoke a stronger response to the antigen, making the vaccine more effective.

And this is important clinically because?

Because allergic reactions.

They're almost always to one of those other ingredients.

The inert additives, maybe trace antibiotics,

egg protein in some flu shots, gelatin, not usually the antigen itself.

Ah, so that's why checking the full ingredient list against allergies is so key.

Absolutely.

You need to look at the package insert.

Okay.

Let's talk about administration and schedules.

Combination vaccines are helpful, less pokes.

Definitely helps with compliance.

But there are acceptable ranges for when doses can be given, which allows for catch -up.

That sounds like a practice management headache.

It can be.

That flexibility is necessary, but you have to have good systems, tickler files, electronic reminders, whatever works to make sure people actually complete the series.

Otherwise they just fall through the cracks.

Makes sense.

Okay.

Let's shift into those special circumstances.

Preterm infants first.

Generally we dose based on chronological age, right?

Mostly yes, but hepatitis B is the big exception.

It's all about the mother's HBS ag status.

Okay.

Break that down.

If mom is HBS ag negative,

the baby gets their first dose either at one month of age or when they're discharged from the hospital, whichever comes first.

Simple enough.

But if mom is positive.

That's an emergency.

The baby needs hep B immune globulin that's passive immunity and the first dose of the hep B vaccine at different injection sites, all within 12 hours of birth.

12 hours.

That's a tight window.

It's incredibly tight and absolutely critical for preventing transmission.

Miss it and the risk goes way up.

Got it.

Okay.

Now the immunosuppressed child may be HIV,

cancer treatment, long -term high dose steroids.

What's the role on live vaccines?

Is it always a no -go?

Generally?

Yes.

Live vaccines are contrary indicated.

There are two main reasons.

One,

the risk that the weakened virus could actually cause disease in them.

Because their immune system can't handle even the attenuated version.

Exactly.

And two, even if they don't get sick from the vaccine, their suppressed immune system likely won't mount an effective protective response anyway.

So the vaccine wouldn't even work well.

So if we can't use active vaccines, how do we protect these vulnerable kids?

We rely on passive immunity again.

Regular doses of immune globulin, often given intravenously IVH, it provides temporary ready -made antibodies.

But you mentioned generally.

Is there any exception for live vaccines and immunosuppression?

There is one very specific narrow exception.

The live varicella chickenpox vaccine.

Under specific compassionate use protocols, it can be considered for children, say, 12 months up to 17 years, who have acute lymphocytic leukemia but have been in remission for at least a year.

Why that specific case?

Because for that group, the risk and severity of getting natural chickenpox is deemed potentially higher than the risk from the vaccine.

But it's a very careful specialist decision.

Understood.

Now, corticosteroids.

This seems like a common clinical scenario with really high stakes for vaccine timing.

It is.

And the key is that deferral of live vaccines depends entirely on both the dose and the duration of the steroid treatment.

Okay, let's walk through the thresholds.

When do we not need to worry about deferring live vaccines with steroids?

You're generally okay if it's topical steroids, inhaled steroids, or injections into a joint.

Also, physiologic replacement doses, like for Addison's disease, are fine.

What about systemic doses?

If the systemic dose is low, meaning less than 2 milligrams per kilogram per day of prednisone equivalent,

or less than 20 milligrams total per day, if the person weighs over 10 kilos,

you generally don't need to defer live vaccines.

Okay,

so low dose or localized is fine.

But what if they hit those higher systemic doses, like 2 milligrams a day or more, or over 20 milligrams total?

Right.

Now, it depends on duration.

If they're on those high doses, daily or alternate days, but for a short period, 14 days or less, you just need to wait until they've completely stopped the steroids before giving the live vaccine.

Just wait till it's stopped.

Okay.

But what if that high dose course lasts longer than 14 days?

Ah, that's the crucial distinction.

14 days or more of high dose steroids causes more significant immunosuppression.

In that case, you must wait at least one month after they stop the steroids before giving any live vaccine.

One month, okay.

That's a critical delay to remember.

Requires really precise tracking.

Absolutely.

You need to know the exact dose, the exact duration.

Before we leave contraindications, quick point on seizures.

The guidance seems different for DTAP versus MMR.

Yeah, it's but context.

For DTAP, which is given early in infancy, if there's a suspicion of a progressive neurologic disorder, like infantile spasms that might be emerging around that time, you should defer the pertussis component.

Why?

It's not that the vaccine causes it, but the timing could coincide, confusing the diagnosis.

You want to see how the neurological picture unfolds first.

But MMR is given later, usually around 12, 15 months.

By then, if a child has a history of seizures, it's usually an established condition.

A known stable history of seizures is not a reason to defer MMR and give it on schedule.

Okay, that clarifies the distinction.

Now let's shift to some specific adult vaccines, which often involve complex choices.

Pneumococcal vaccine you mentioned, Pneumonia, is a major killer.

Huge.

Pneumococcal disease kills about 5 ,000 people a year in the US more than any other vaccine -preventable bacterial disease.

So vaccination is key.

And we have two main vaccines here, PCV13 and PPSV23.

What's the difference?

So PCV13, Prevnar13 is a conjugate vaccine.

It links the polysaccharide antigen to a protein, which triggers a stronger T -cell dependent immune response, especially good for immune memory.

PPSV23, Umovax23 is a polysaccharide vaccine.

It covers more serotypes 23 versus 13.

But the immune response is generally less robust and shorter lived.

Okay, so who needs this?

Definitely everyone 65 and older.

And then younger adults, say 19 through 64, who have specific high -risk conditions,

chronic heart, lung, or liver disease, diabetes,

alcoholism, smokers.

Also people without a functioning spleen or who are immunocompromised.

The list is quite detailed.

Got it.

For the 65 plus group, what's the strategy now?

Do they get both?

Yes, generally.

All adults 65 and older should get PPSV23.

The recommendation for PCV13 in this age group is now based on shared clinical decision making between the patient and provider.

Okay, and if they do get both, is there a specific order?

Yes, absolutely.

If someone hasn't had either vaccine before, you give PCV13 first.

Why first?

Giving the conjugate vaccine, PCV13, first seems to prime the immune system for a better overall response.

Then you give PPSV23 usually one year later.

One year later.

Okay.

What about revaccination?

Do people need boosters?

Generally, revaccination with PPSV23 is recommended only once for those at highest risk.

Like Asplenia or immunocompromised.

And for those initially vaccinated before age 65, who are now 65 or older, provided at least five years have passed since the previous PPSV23 dose.

There's no data supporting more than two lifetime doses of PPSV23 for most people.

Okay, complicated but critical.

Let's move to influenza.

Who needs the flu shot?

Pretty much everyone.

Anyone aged six months or older every single year,

universal recommendation.

There are different types, right?

The shot versus the nasal spray.

Correct.

You have the inactivated influenza vaccine,

or that's the standard flu shot.

Then there's the live attenuated influenza vaccine, LAIV, which is the nasal spray.

Full missed.

And the LAIV being live has some specific contraindications.

Big ones.

Yeah.

It's contraindicated in anyone who's immunocompromised.

But also, and this is key, it's generally not recommended for their close contacts or health care workers who care for severely immunocompromised patients in protected environments.

Why not for the contacts or health care workers?

Because the person who gets the live nasal spray vaccine can potentially shed the weakened virus for a short period.

So if they're around someone severely immunocompromised, there's a theoretical, albeit small, risk of transmission.

The guidance is if they do get LAIV, they should avoid contact with those severely immunocompromised individuals for seven days.

Wow, okay.

That's an important counseling point.

Any specific dosing considerations for flu?

Yes.

Annual dosing is needed because the circulating strains change.

For adults 65 and older, there's a high dose IFA available, designed to elicit a stronger immune response in older adults whose systems might not respond as robustly.

And what about kids?

Kids aged six months through eight years who are getting vaccinated for the very first time need two doses in that first season, given at least four weeks apart, to build adequate immunity.

Got it.

Two doses for the newbies under nine.

Okay.

T -dap tetanus, diphtheria, a cellular pertussis.

This has expanded beyond just childhood series, right?

A single dose of T -dap is recommended for adolescents, usually around age 11, 12, and then for adults who haven't had one before.

It substitutes for one of the routine TDs boosters.

But there's a really critical indication for T -dap in pregnancy.

Absolutely non -negotiable standard of care now.

Every pregnant woman needs one dose of T -dap during each pregnancy, ideally between 27 and 36 weeks gestation.

Each pregnancy, why?

To maximize the mother's antibody levels late in pregnancy, so she passes high levels of protective antibodies against pertussis when we go off to her baby before birth.

This protects the infant during their most vulnerable first few months.

Makes perfect sense.

Okay, briefly HPV vaccine.

Human papillomavirus vaccine.

Routine vaccination recommended at age 11 or 12 can start as young as nine.

It's usually a two or three dose series, depending on age and initiation.

Catch -up is recommended through age 26 and shared decision -making for ages 27, 45.

Key contraindication, pregnancy.

Right, and rotavirus.

That one has a famously tight schedule.

Infamously tight.

Rotavirus causes severe gastroenteritis in young kids.

The vaccine is oral.

The first dose has to be given before the infant turns 15 weeks old, ideally starting around 6 -12 weeks.

Before 15 weeks for the first dose.

Yes, and all doses in the series must be completed before the child reaches eight months of age.

After that, it's too late you can't start or continue the series.

That requires meticulous tracking and pediatric practices.

Definitely.

No room for error there.

Okay, let's try to pull this together with a quick case application.

Think about DB from the case study 22 years old works as a nurse's aide and she smokes.

What vaccines jump out immediately based on just those facts?

Okay, multiple flags there.

Nurse's aide healthcare worker means she absolutely needs documented immunity or vaccination for hepatitis B, likely hep A too, depending on the setting.

MMR, varicella, and annual flu shots.

And the smoking?

Smoking puts her in a high -risk category for pneumococcal disease, even at age 22.

So what's her pneumococcal plan?

Because she's under 65, but has that risk factor, smoking,

she should receive PCV13 first, followed by PPSV23 at least one year later.

Okay, what else for a 22 -year -old?

She definitely needs a Tdap booster if she hasn't had one as an adult.

And she's right in the age range for HPV vaccination if she hasn't completed that series.

See, that's the kind of synthesis needed pulling together occupation, age, risk factors.

Now, let's throw a wrench in it.

What if DB needs an emergency splenectomy?

How does that change her immediate vaccine needs?

Splenectomy drastically increases risk for sepsis from encapsulated bacteria,

pneumococcus, Hib, meningococcus.

Ideally, you vaccinate before the splenectomy, but if it's an emergency - Right, post -op, what's needed?

She needs several vaccines, ideally before discharge or within 14 days post -op.

That includes PCV13, even if she already had it, the timing might need adjustment relative to PPSV23.

Hape vaccine, meningococcal conjugate vaccine, MenSCWY, and also meningococcal B vaccine, MenB.

That's a lot immediately post -op.

It is, but the risk is that high.

And then she'll need the PPSV23 dose eight weeks after PCV13,

and regular boosters of MenSCWY every five years, possibly PPSV23 too.

It's a lifelong increased risk.

That really highlights the importance of identifying those high -risk conditions.

Okay, nearly done.

Let's summarize the absolute universal contraindications again.

The main ones are a history of a severe allergic reaction, like anaphylaxis, to a prior dose of the vaccine or to one of its components.

You have to know what's in it.

Like egg allergy for some flu vaccines or neomycin gelatin in others?

Exactly.

And the other big one is moderate or severe acute illness.

With or without fever, you'd postpone vaccination until they're better.

But a minor illness, like a cold low -grade fever, that's not a contraindication, right?

Correct.

Mild illness is not a reason to delay vaccines.

That's a common misconception that leads to missed opportunities.

And if an adverse event does occur or is suspected, what's the procedure?

Reporting is crucial.

We use the Vaccine Adverse Event Reporting System, VAEAR.

It's a national system set up after the Childhood Injury Act of 1986.

What information do you need to report?

You need a detailed description of the event, the timing relative to vaccination,

patient info like allergies or immune status, and specifics about the vaccine manufacturer or lot number, where it was given.

It's vital for monitoring vaccine safety.

So as advanced practitioners, we're responsible for recognizing, managing, and reporting these events.

Absolutely.

It's part of the job.

Okay.

So wrapping up our deep dive today, we've gone from the basics of active versus passive, really drilled down on those corticosteroid rules.

Nailed the PCV13 PPSV23 strategy for adults.

And reinforce critical points like Tdap in every pregnancy and those tight rotavirus windows.

I think the final thought, the real takeaway for practitioners has to be about systems.

How so?

Knowing all this is great, but if you don't have a system in your practice to routinely check immunization status at every visit,

not just well visits, but sick visits too, you will miss opportunities.

So building that review into the workflow.

Exactly.

Chart reminders,

standing orders where appropriate,

making it automatic.

That's how we close these persistent gaps,

especially for adolescents and adults who often don't have regular, well, checkups.

Every encounter is a chance to vaccinate.

Make every encounter count.

A perfect challenge to end on.

Thanks so much for walking us through all these complexities.

My pleasure.

It's incredibly important stuff.

And thank you all for joining us for this deep dive.

We'll catch you next time.