Frequently Asked Questions By Providers

Welcome to our FAQ page.

Why are vaccinated people getting Pertussis?

The resurgence of Pertussis is a nationwide phenomenon; however, the problem has been particularly pronounced in Washington State, where we are having our worst outbreak in decades. One striking characteristic about the current Pertussis epidemic is the fact that cases are frequently occurring in persons who have been vaccinated against Pertussis--and even in those who have a confirmed history of whooping cough.

It is often asked if this is a result of a possible mismatch between the serotypes of Pertussis contained in the vaccine and those circulating in the community (evidence of such a mismatch has been found in multiple places). It is conceivable that this might be contributing to the problem, although there isn’t good evidence for this at this time. What clearly does appear to be the primary contributing factor is the fact that neither infection nor vaccination appears to produce lifelong immunity to Pertussis.

Data on duration of immunity following vaccination is variable. Older studies had suggested that vaccine-induced immunity only lasted 4-to-12 years in most people, but more recent studies (done on populations of children who have only received the newer acellular vaccine, i.e. DTaP) suggest that the problem may be even worse; they show that rates of infection increase markedly only three years following immunization. Even for those who become infected with wild-type Pertussis (i.e. who catch whooping cough), immunity is not long-lasting. It is estimated that immunity following infection is only 4 to 20 years.

This means that teenagers and adults are very often susceptible to Pertussis infection--and in fact catch it quite frequently. Because the symptoms of early Pertussis infection aren’t particularly distinctive (it looks exactly like the common cold), these people don’t isolate themselves from others, and therefore will often pass the infection on to high risk persons (e.g. young un-immunized infants) or to other susceptible persons who in turn can pass it on to high-risk individuals.

Upon hearing this information, the reaction of some parents has been something along the lines of “Well, if this is so ineffective, then why bother vaccinating for it?” Ironically enough, however, the very fact that vaccine-induced immunity wanes so quickly provides the strongest argument for attempting to vaccinate the greatest number of people.

In order to limit epidemic spread of disease, it is necessary to minimize the likelihood that an infected person will be exposed to someone to whom they can transmit the disease. This is relatively easy to do if most of the population has lifelong immunity from vaccination or illness (a “measles outbreak” is often limited to one or two dozen people) or if a disease does not spread easily with casual contact. Pertussis is a prime example of the opposite case; it spreads very easily from person to person, and because immunity to Pertussis fades over time, there are always large numbers of people that are susceptible to infection. Because we will not ever be able to depend on having a large population of persons that are permanently immune to Pertussis, it is critically important that we make sure that as many people as possible have been vaccinated in the recent past.

Therefore, essentially everyone that was vaccinated in young childhood or who had whooping cough in the past will need to be re-vaccinated at some point. CDC recommendations have recently been revised with this in mind:

-- All children age 11-and-up are to receive a single dose of Tdap now if they have not already done so (the old “minimum interval” of two years since the last Tetanus booster no longer applies).
-- Adults that have never received Tdap in the past are to receive a single dose of this.
-- Pregnant women who have not previously received Tdap should be vaccinated. This should ideally occur in the second half of pregnancy (though there isn't any absolute restriction on earlier dosing if necessary).
-- The vaccine is only FDA-labeled for use between ages 10 (or 11, depending on product) and 65. However, the CDC has recommended that any child aged 7 to 10 that was not fully immunized with the childhood form of the vaccine (DTaP) receive an off-label single dose of Tdap, and also that adults over 65 receive an off-label single dose of Tdap.

Another common question is whether a person that received the Tdap vaccine several years should be given a booster. The answer to this is currently “no”. However, that may change in the near future. Because rapid waning of immunity associated with DTaP vaccine is now well-documented, it is suspected that a similar phenomenon may very well occur following Tdap vaccination, and that therefore there will eventually be a recommendation for at least one booster dose of Tdap. However, data on this is only now becoming available (the vaccine was only licensed seven years ago), so there is not yet FDA approval for a second dose of the vaccine in any population. The CDC-ACIP and AAP, similarly, have not yet recommended more than one lifetime dose for anyone, and even though there's a local epidemic, neither the State DOH nor the King or Snohomish/Pierce County Health Departments nor local infectious disease experts are recommending a second dose of Tdap in anybody for any reason at this point.

How do I respond to parents who don't want the Hepatitis B birth dose because their babies are at such low risk?

Questions about the timing of the first dose of Hepatitis B vaccine (e.g. administration shortly after birth, rather than at two months of age) are quite common. The logic behind the question is understandable: Hepatitis B is transmitted by blood and body fluids, meaning that it is usually acquired through sexual activity, IV drug use, or engagement in activities with multiple persons in which there is a possibility of broken skin and exposure to blood.

The reason for which the first dose is given at birth, however, has little to do with the risk of contracting Hepatitis B in the community. Rather, it is done in order to minimize the risk associated with perinatal transmission of the virus from a mother with an unrecognized infection to her newborn infant. Administration of Hepatitis B vaccine (as well as Hepatitis B Immune Globulin) within the first few hours after delivery significantly decreases the likelihood that an exposed infant will actually develop Hepatitis B infection.

3,400 newly-diagnosed cases of Hepatitis B were reported to the CDC in 2009, and it is felt that this likely represents only a small fraction (possibly as little as 10%) of the actual number of new infections that occurred. Roughly 25,000 women with chronic Hepatitis B infection give birth in the United States each year – and although screening of expectant mothers for Hepatitis B is now commonplace in the U.S, this has proven to be an imperfect process, and maternal infection can still easily be missed.

Certain subsets of women are, of course, at much greater likelihood of having unrecognized infection (e.g. those with limited or no postnatal care). However, even women that are followed regularly during pregnancy will occasionally have unrecognized infection. The proper test used to identify chronic infection is HBsAg; however, HBsAb is sometimes ordered by mistake. Even when the correct test is ordered, the results may be mis-transcribed, or even misinterpreted. For example, a positive result for HBsAb is good (indicates immunity), but a positive result for HBsAg is bad (indicates active infection). In addition, the possibility always exists that the mother contracted Hepatitis B late in pregnancy (after screening labs were drawn).

The end result of this is that although most maternal Hepatitis B infections will be recognized prior to delivery, some will not, and the consequences of missing the opportunity to provide at least some post-exposure prophylaxis (i.e. vaccination) are potentially disastrous. In the absence of post-exposure prophylaxis, the likelihood of infection in cases of perinatal transmission is extremely high (between 70% and 90%), and if infection occurs, this is likely to be a lifelong condition. Up to 90% of infants who acquire Hepatitis B at birth will become chronically infected (in contrast to adults, only 5% of whom develop chronic Hepatitis B if infected). This will place them at substantially higher lifetime risk for cirrhosis and hepatocellular carcinoma.

The principle-of-practice here is analogous to the principle that we follow when a two-week-old develops a high fever and is irritable. We do a spinal tap on all of them, admit all of them to the hospital, and start IV antibiotics on all of them while waiting for the culture results. We do this not because there’s a high likelihood of meningitis; even though the vast majority (way over 90%) of these kids will end up having some benign illness that requires no treatment at all, a small fraction actually will have meningitis. Rather, we test all of them for it because the downside of not treating one of the infrequent kids that actually does have meningitis is enormous.

All of that said, realistically, this is not a battle that can always be won, or that you will even always choose to fight. There will be parents who remain adamant that there is absolutely no likelihood that they could have an unrecognized Hepatitis B infection, and who will refuse to have the first dose given at birth despite everything said above. In most cases, these parents will in fact be correct. If maternal testing for Hepatitis B was done recently, done correctly, recorded properly, and the social situation is such that the likelihood that the mother has contracted Hepatitis B since the test was done and/or that the infant will contract Hepatitis B in the home are truly quite low, then you may well choose not to damage your relationship with (and, by extension, your degree of influence over) such a family by insisting on this. However, they should understand that the Hepatitis B vaccine is safe and well-tolerated, and the potential benefits of the birth dose still outweigh any theoretical risks.

What can MAs do to help doctors in reaching the goal of higher immunization coverage?

Questions like this are always a little bit difficult to give specific answers to because the role of each member of the care team varies greatly from practice-to-practice.

That said, there are a few basic principles that hold true for almost everyone. You’ll note that some of these guidelines relate to helping with immunization hesitancy…but others deal with simply making sure that opportunities for vaccination aren’t missed. Many children are behind on immunizations not because their families don’t want to get them, but because they haven’t been coming in for all of their well-child visits (or otherwise have missed scheduled vaccinations).

To help with HESITANCY …

1) Present a united front! During the training, I pointed out that among vaccine-hesitant parents that ultimately decide to vaccinate, the most important factor influencing their decision was the recommendation from their child’s provider. By extension, this includes YOU! I have often had new families that hadn’t met me yet and were unsure whether they’d feel comfortable asking me what I thought about vaccines…so they’d ask my flow staff instead. Answering doesn’t require any particular knowledge about vaccines – just letting them know that “yes”, you and the others all feel that immunizations are very important for their infant’s health and well-being will help. If you have kids yourself, and had them vaccinated on schedule, let them know that, and let them know that you felt absolutely safe in doing so.

2) Screen for red flags! When you ask if the parents “have any questions” while rooming a child, if you know that this is a typical vaccine visit (e.g one of the checkups in infancy), ask if they have any questions for the doctor about the immunizations to be given that day. If they say yes, make a note of it, and pass the information on to the provider. That way they can be sure to make time for the conversation during the visit.


1) Screen records in advance! At our clinic (and many others), the flow staff reviews the immunization record when preparing for the visit (often the day before) and figures out whether any regular immunizations are due—and whether any catch-up vaccines are needed. They will then collect all of the necessary consent forms and Vaccine Information Sheets, fill them out, and have them ready to go at the time of the visit. This minimizes the time that the doc needs to spend on paperwork, and, by extension, minimizes the likelihood that the conversation will get forgotten or that missing doses will be overlooked.

2) Consider EVERY visit an opportunity for vaccines! Our staff does the screening described above for every single child that comes in all day long, whether for a well-checkup, an ear infection, or a broken arm. There will occasionally be situations where I’ll decide not to give the vaccine, but bona fide contraindications to immunization are actually few and far between (there’s no problem with giving immunizations during mild illnesses). This makes the screening and advance-preparation described above especially important! Because these aren’t what we’d normally consider “vaccine visits”, it may very well not cross my mind to discuss them (or I may not want to spend the time) unless the forms are right there in front of me to remind me, and already filled out so that I can touch on the issue with a minimum of fuss.

What is the problem with Dr. Sears' 'alternative schedule'?

Dr Robert Sears published “The Vaccine Book: Making the Right Decision for Your Child” in 2007. This book addresses concerns that many parents have about vaccines; however, it does so in a way that propagates factual errors and unfounded concerns that have caused vaccine hesitancy to become such a widespread phenomenon.

One of the most popular elements of this book is the two alternative immunization schedules contained therein – “Dr Bob's Selective Vaccine Schedule” (for parents who want to decline or delay vaccines) and “Dr Bob's Alternative Vaccine Schedule” (for parents who are concerned that their children are receiving too many vaccines at once and wish to space them out).

The misguided advice contained in this volume – and the inaccurate information on which Dr. Sears guidance is based – is far too extensive to address in depth here (Paul Offit & Charlotte Moser from the University of Pennsylvania published a journal article on this very subject that ran six pages in length). For those interested in their specific concerns about Dr. Sears’ recommendations, this article was published in the journal Pediatrics in 2009 (Pediatrics Vol. 123 No. 1 January 1, 2009 pp. e164 - e169).

The general concern with using these alternative schedules is that they introduce the potential for harm (by allowing children to remain temporarily or permanently unprotected against vaccine-preventable diseases) while offering no proven benefit. Children vaccinated according to Dr. Bob’s “Selective” schedule will remain unvaccinated for several conditions, including polio and influenza (and, possibly, MMR, among others). And although children vaccinated on Dr. Bob’s “Alternative” schedule will have only minor delay of some vaccines, they will not be vaccinated against hepatitis B until age 2-and-a-half, against measles until age 3, and against influenza vaccine until age 5. Such delay is not necessarily benign; as Dr. Offit points out in his critique, tens of thousands of children under age 4 are hospitalized every year with complications resulting from influenza.

In most cases, the recommendations made by Dr. Sears do not even have a sound theoretical basis, based as they are on erroneous assumptions. And, yes, that statement about “no proven benefit” actually HAS been investigated. A 2010 study by Michael Smith from the University of Louisville School of Medicine examined data (results of several standardized tests) from over 1,000 7-to-10 year old children who were first vaccinated between 1993 and 1997. He compared the results for a subset of children that were vaccinated on time with the results from a group whose vaccinations were delayed. There was no single variable examined on which the children with delayed vaccinations outperformed those who were vaccinated on time.

Lastly, Dr. Sears clinic is one of extremely few in the country to have experienced a measles outbreak because unvaccinated children spread the disease to one-another.

What is the risk of autism from vaccination? Where did this information come from?

The short answer is that there doesn’t appear to be any risk. This issue has been researched in considerable depth in several countries over the past decade-plus, and studies have consistently shown no relationship between immunizations and autism spectrum disorders.

Those who are concerned about a possible relationship between vaccines and autism have proposed various mechanisms for this, and will cite studies that suggest such an association. However, each of the proposed mechanisms – including “use of Thimerosal preservative”, “simultaneous administration of Measles, Mumps, and Rubella vaccines”, “administration of large numbers of vaccines simultaneously”, etc – has been examined and refuted in subsequent studies. To date, there are no studies involving individual-level data and original data sets that suggest an association between vaccines and autism.

This question first arose because the percentage of children diagnosed with autism has risen steadily since the early 1990s – and this happened to be a period during which some new vaccines were introduced into the routine childhood immunization schedule. However, this was about the time that the diagnostic criteria for autism were revised to include Autism Spectrum Disorder (ASD), Asperger’s, PDD, Rett’s, etc. This greatly increased the number of children to whom this diagnosis could be applied; in fact, the vast majority of children that fall into this category today would not have qualified for an Autism diagnosis in 1990. There is evidence to suggest that many were simply classified as having other conditions – there are studies that show that as the incidence of autism-spectrum diagnoses rose during the 1990s, the incidence of “mental retardation” and “learning disability” diagnoses declined(1).

The early 1990s was also about the time that autism spectrum disorders were added to the list of diagnoses that would qualify a child for school-based services under the Individuals With Disabilities Education Act (IDEA). As the implications of this change became understood in the education and lay communities, having one’s child labeled with a diagnosis of ‘autism or ‘autism spectrum’ evolved from being a stigma (that was strongly resisted by families even in fairly profound cases) to being something actively-sought-after by families (even in milder cases).

The resulting increase in milder cases being brought to medical attention (where they may not have been in the past) has likely had a profound effect on the rate of diagnosis. Only two years after adding autism to the list of qualifying diagnoses for services under IDEA, the Department of Education reported a 23% rise in autism spectrum diagnoses.

1. Shattuck “Contribution of Diagnostic Substitution to the Growing Administrative Prevalence of Autism in US Special Education” Pediatrics 2006;117;1028-1037.

How do you encourage adults to update to Tdap from Td? Their response is usually, ‘No, I don’t spend a lot of time around children.’

The key here is to emphasize that even though they’re not around children, they are still at personal risk of contracting Pertussis, and can still place young infants at risk of contracting Pertussis.

The immunity conferred by the Pertussis vaccine – and, for that matter, the immunity conferred by Pertussis infection – is not permanent. A person who contracts clinical Pertussis will have immunity for a few years following the infection, but within 5-to-20 years this immunity will have waned, and they can again become infected. Vaccine-induced immunity fades even more quickly – recent studies have suggested that within 3 to 12 years people are again susceptible to disease. Consequentially, many adults who assume that they are immune to Pertussis are, in fact, not.

Because this may appear clinically to be nothing more than a cold-with-a-cough in its early stages, infected adults will generally not isolate themselves from others or seek care until well into the illness; in the interim, they will spread the infection to potentially large numbers of family members, friends, and colleagues.

Therefore, an un-immunized adult can easily contract Pertussis even if they aren’t around children because most adults catch Pertussis from other adults.

Similarly, an un-immunized adult can play a role in transmitting Pertussis to young infants, even if they have no personal contact with children. If such an adult becomes infected, they will be contagious for some time before they even begin to cough, they will very likely transmit the infection to other adults, some of whom may have daily contact with infants too young to be vaccinated.

This serves as a classic example of the importance of “herd immunity” in control-of-disease-outbreaks.

How do you respond to patients that believe vaccines are not effective?

This is the sort of question that lends itself to the impulse to simply bludgeon people over the head with data – the numbers are so overwhelming that it’s simply hard to look at them & draw any other conclusion…

In these cases, try to elicit the source of this impression that vaccines, and then gently remind them of little facts that would suggest otherwise. Personal anecdotes are particularly helpful in these situations; if you’ve had the experience of caring for a child with Haemophilus meningitis, it was likely an experience that you would never again wish to undergo. If you have children or families in your practice who have been the unfortunate victims of some of these conditions, a story about the child with deafness from congenital Rubella will be much more effective than statistics about the decline-in-disease-rates.

If, on the other hand, you need to convince somebody with hard facts, then present them with this data (from the CDC’s “Epidemiology and Prevention of Vaccine-Preventable Diseases”, Vol. 12, pub. April 2011).

Remember, these diseases didn’t go away by themselves!

1950 cases/deaths: 5,796/410
2007 cases/deaths: 0/0

1950 cases/deaths: 486/336
2007 cases/deaths: 28/5

1950 cases/deaths: 120,718/1,118
2007 cases/deaths: 10,454/9

Polio (paralytic)
1950 cases/deaths: 33,300/1,904
2007 cases/deaths: 0/0

1950 cases/deaths: 319,124/468
2007 cases/deaths: 43/0
1966 cases/deaths: 46,975/12
2007 cases/deaths: 11/1

1968 cases/deaths: 152,209/25
2007 cases/deaths: 800/0

1972 cases/deaths: 164,114/122
2007 cases/deaths: 40,146/6

Hepatitis A
1979 cases/deaths: 30,407/129
2007 cases/deaths: 2,979/34

Hepatitis B (1)
1979 cases/deaths: 15,242/260
2007 cases/deaths: 4,519/719

Haemophilus type B (2)
1980 cases (estimated): ~20,000
2010 cases: 23

(1) Hepatitis B deaths climbed steadily during the 1980s and early 1990s (peaking at 1120 in 1994), and have fallen since. Routine vaccination of all newborns was recommended beginning in 1991.

(2) Haemophilus reporting includes ALL serotypes—therefore, Haemophilus-type-B is not included here. However, by 2010, only 23 cases of invasive Haemophilus-type-B disease were reported nationwide among children younger than 5 years of age.

The concept of the Paleolithic Diet (or “Paleo Diet”) is based on the idea that humans are probably genetically predisposed to be most tolerant of, and therefore most likely to thrive on, a diet resembling that of our Paleolithic ancestors. Oversimplified, this implies a pre-agricultural diet consisting of plants and animals (e.g. meat, fish, wild fruits and vegetables, fungi, nuts, roots, etc.) similar to those that were probably consumed by humans from the Paleolithic Era until about ten thousand years.

Several studies of the possible benefits of such a diet have been done since the 1990s. A review of the scope/findings/quality of such studies is beyond the scope of this article. However, none appear to have directly investigated any correlation between adherence to a Paleolithic Diet and susceptibility to vaccine-preventable diseases. A PubMed search of abstracts and MeSH terms for various combinations of “Paleo” or “Paleolithic” plus “Vaccine” or “Vaccination” or “Immunization” or “Immunized” yields literally no scientific articles at all. Similarly, a review of a fairly comprehensive listing of published papers on the Paleolithic Diet (obtained from a website that champions this nutritional plan) turned up no research that examined this subject.

Numerous articles, books, and online postings do speculate on such a benefit. However, to date I have found none that draw on or cite any direct evidence in support of this.

In truth, the underlying premise behind such a connection may be flawed. In theory, a Paleolithic Diet would lead to improvement in overall health, with associated improved outcome measures. Proponents often cite studies suggesting that populations that consume a diet similar to this are free of many diseases (e.g. heart disease, stroke, obesity, hypertension, diabetes, etc) that are found in more developed areas where “modern” diets are consumed. However, there do not appear to be well-done studies that suggest that such populations have a significantly decreased likelihood of contracting specific vaccine-preventable infectious diseases.

Nor is there necessarily a reason to believe that this would be case. Gross malnutrition can certainly cause a person to be more susceptible to infection in general, and some proponents of the Paleolithic Diet truly believe that such diets can lead to decreased susceptibility to mild infections. However, the sort of severe infections against which we now vaccinate are in many cases anything but mild, and in the past would afflict the previously-healthy and previously-unhealthy alike.

When is it appropriate to use the combination MMRV (MMR and varicella) vaccine, and when should these be given separately?

Both Varicella vaccine and MMR vaccines have been available and widely used since the 1990s or earlier. In September 2005, a combined MMR/varicella vaccine (MMRV) was licensed by the FDA for use in children aged 12 months through 12 years. Administration of the MMRV vaccine was – and is – considered equivalent to administration of separate varicella and MMR doses.

There are a few notable exceptions to this general rule that relate to the association of MMRV with febrile seizures:

1) Research suggests that children with either a personal history or family history of febrile seizures, or with a family history of epilepsy, are more likely than those without such a history to have febrile seizures as an adverse reaction to use of MMRV vaccine. Therefore, children with any personal or family history of seizures of any type should usually be vaccinated with separate MMR and Varicella vaccine rather than with MMRV (the word 'usually' is used because there are certain instances where the MMRV benefit outweighs the risks (e.g. in a a measles outbreak)).

2) There are two studies showing a very slight increase in the rate of febrile seizures when MMRV is given to otherwise-healthy children under age two. This increase was very small, and this increase in risk does not appear to be present in children 4–6 years of age who are receiving the second dose of MMRV vaccine.

Because of this, the CDC states that although either separate MMR vaccine and varicella vaccine or MMRV vaccine may be used for the first dose in children under age two, “providers who are considering administering MMRV vaccine should discuss the benefits and risks of both vaccination options with the parents or caregivers...unless the parent or caregiver expresses a preference for MMRV vaccine, CDC recommends that (separate) MMR vaccine and varicella vaccine should be administered for the first dose in this age group”.

With regard to the second dose of MMR & varicella (or for the first dose if this occurs at 48 months of age or older), the CDC states that “use of MMRV (combination) vaccine generally is preferred over separate injections”.

Vaccine-hesitant parent of a 2 month-old infant was advised by adult friends that vaccines ‘harm’ people. One friend suffered terrible mood swings after vaccination; another immune deficiency. How to address?

Questions like this one are exactly why the AAA protocol was developed. This really isn’t a question so much as an expression of general anxiety about vaccines. At some point, most parents hear stories like this mother is relaying, but only some of them are concerned enough to actually delay vaccination. This parent trusts the sources of these stories enough to give them credibility and consider going against your medical advice. You likely won’t ever be able to discredit these people and their claims, but you can build a trusting relationship that will cause your advice to have the most weight at a later date. The key here is not to plunge into the science of these two issues (mood changes and immune deficiency), though it is fine to say that vaccines have never been shown to have widespread side effects like these or they would not have broad approval for use in the general public.

The ideal approach, rather, is to listen thoughtfully and carefully to the parent’s concern, and find a way to enter the vaccine schedule slowly (having just one vaccine now to allow the parent to monitor progress). Confirm that many parents have questions and that there are a lot of stories circulating about vaccine safety or lack thereof. Applaud the parent for asking these questions because it means that he or she wants what is best for the child. Conclude by stressing that your conviction that vaccines are best for the child is very firm, but that you are willing to work with the parent’s hesitancy. Most likely this will mean a delayed schedule. The likelihood is that you won’t have total success on the day of the conversation, but it might allow for some vaccinations and it will definitely allow for the conversation to be respectfully and productively approached in the future.

While surely frustrating to the physician in this situation because he or she can’t handle this with the desired outcome straight away, communication science tells us that this is the best way to handle these general anxieties. The parent herself likely cannot put her finger on the source of her concern, which means that it can’t be addressed wholesale at once. Stay this course of developing trust and you are most likely to get the child immunized and eliminate these (spurious) concerns.

Is there any evidence of a relationship between immunization and Sudden Infant Death Syndrome (SIDS)?

The best brief summary on this topic is on the CDC site. They have a nice one-page monograph ( with links to the 2003 Institute of Medicine report (on the relationship between vaccines and SIDS and neonatal death) and a few other relevant studies.

As we know, however, vaccine-hesitant families often look askance at information from the government, industry, and even universities on this subject. They might therefore perceive the National Network for Immunization Information (NNii) website as being a more "credible" resource. NNii does have a somewhat-more-brief article ( on this topic; this article goes into far less depth & detail than does the CDC page, and does not contain a reference list. It does, however, contain a direct link to the IOM report.

The IOM report ( was a comprhensive review of the then existing literature on the subject (it's about a hundred pages long). Briefly summarized, they found that the evidence favored rejection of a causal relationship between receipt of multiple vaccines and SIDS, and that the evidence was inadequate to accept or reject a causal relationship between any single specific vaccine and SIDS, SUDI, or neonatal death.

The question tends to still come up in part as a result of a 2004 paper by Geier & Geier that suggested a link between DTaP and SIDS. However, when the IOM re-examined DTaP and SIDS in their massive 2011 report on "Adverse Effects of Vaccines", this study was rejected from the analysis because it drew it's data from a "passive surveillance system" (VAERS, I believe) and had no unvaccinated control group for comparison. Note that there was an analysis of VAERS data done a few years earlier that had demonstrated declining rates of SIDS deaths reported following vaccination during the 1990s, despite an increase in the number of vaccines in infancy. The Geiers have also been thoroughly discredited in the intervening years, with the elder Geier having his medical license suspended (the younger has not formal scientific training).

A 30-week premie is in the office for a 2-month visit. Why is it OK to give her vaccines designed for a 2-month od when she isn't supposed to be born yet?

The question is a good one. On the one hand, there is concern that even full-term infants may not produce an adequate (or long-lived) response to some immunizations if these are administered too early. On the other hand, however, there is also concern that preterm infants are a population at potentially higher risk of severe illness and/or complications if they do contract some of these vaccine-preventable diseases. For this reason, this is an issue that has actually been fairly well investigated.

A premature infant, of course, is not actually the equivalent of a fetus newly-weaned from the mother’s body. A 30-week infant that is now two months old will indeed seem to resemble a newborn in some ways (e.g. many developmental milestones will not be met at a two-month level). However, in other ways they will be far more like a full-term two-month-old than like a newborn – for example, their ability to self-regulate temperature & tolerate bolus feedings with wide intervals will be far superior to that of a newly-delivered full-term infant. Similarly, their immune system will have been exposed to a wide array of foreign antigens by this point, and will have been required to react in a way that would not be necessary for a fetal immune system.

The upshot of this is that even though a premature infant technically “shouldn’t even be born yet”, there is a reason to believe that he or she might respond reasonably well to immunizations anyway … and the studies performed on pre-term (PT) & very-low-birthweight (VLBW) infants suggest that this is, in most situations, the case. Safety, immunogenicity, and efficacy of DTaP, IPV, Hib, & PCV vaccines given to PT & VLBW infants at a chronologic age of two months are similar to what is seen in full term infants. In certain situations, the response to vaccine may be less-than-typical – however, the alternative (i.e. leaving a vulnerable premature infant un-immunized) is felt to be risky enough that administration of vaccines on-schedule is still warranted.

There are certain exceptions to this general principle. Immunization of medically unstable infants (who, by definition, will still be hospitalized) is generally deferred until their condition has fully stabilized. Decreased Hepatitis B sero-conversion rates may occur in VLBW preterm infants (BW<2,000g) – however, by 1 month of age, all preterm infants (regardless of initial BW or gestational age) are as likely as older & larger infants to mount an adequate immune response to Hepatitis B vaccination. Therefore, Hepatitis B vaccination would usually be deferred until one month of age unless there is a risk of maternal-child transmission of Hepatitis (in this case, the infant would be vaccinated per protocol; however, this would not count as one of the three required doses in the Hepatitis B series).

How do I know vaccines are safe when so much conflicting safety data comes out regularly?

There is at least some conflicting evidence that exists for virtually everything in medicine. This is in part due to the very nature of science – specifically the fact that any study performed on consecutive groups of people will rarely give the same result twice. For this reason, standards of care in medicine are generally based upon the aggregate information provided by multiple studies, which, when taken together, will tend to provide a more accurate assessment of the actual situation than the information that comes from any single study alone.

This is also, however, in part a result of the fact that the quality of published studies can vary hugely with regard to issues such as study design, methods of data collection, control for confounding, appropriate statistical analysis, and interpretation of findings. Much of the “data” that is cited as suggesting that vaccines are associated with a high rate of serious complications falls into this category. The truth is that where vaccine safety is concerned, there’s actually very little “conflicting” data.

A good example of this is illustrated by the analysis on vaccines and autism that was performed several years ago by the Immunization Safety Review Committee (which was established by the by the Institute of Medicine to evaluate the evidence on possible causal associations between immunizations and certain adverse outcomes). A link to the full paper can be found here:

This analysis was undertaken during a period in which public concern about a possible association between vaccines and autism was very high (both in the U.S. and worldwide), and during which time there had been published a large number of papers suggesting either the presence or absence of such an association – in short, the “conflicting data” about which so many people are concerned. However, in the end it turned out that the data was actually fairly consistent.

The review of literature was literally exhaustive--reviewing and thoroughly assessing virtually every paper published on the subject up to that time (as well as other data). The conclusion reached following this review was unequivocal: It was not only felt that the overall body of evidence did not demonstrate an association between vaccines and autism, but that the evidence actually favored “rejection” of such an association. That is, the well-done studies were fairly uniform in their findings that vaccines did not appear to be associated with the significant increase in autism rates.

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