Immunizations in Children

Dan Onion, MD, MPH

Mt. Vernon/Vienna Health Officer


April 2019

In these current times, some parental reluctance to immunize children is bringing back the old days a bit. There was a case of mumps in York county just last month. In Maine, during the first 3 months of 2019, there were 145 cases of whooping cough (pertussis) and 48 cases of chickenpox (varicella). And that’s not a one-off either; in 2018 there were a total of 446 cases of whooping cough and 252 cases of chickenpox! And right now, there are measles epidemics spreading across the country with nearly 500 cases reported this spring, the most since 1994; the closest cases are in Massachusetts. It’s a potentially a fatal disease in young and/or sickly children, especially in developing countries where it has a 2-10% mortality in kids and in rare cases can cause an encephalopathy 20 years later in adults who had cases as children.

What immunizations are currently required for children to attend public school in Maine? These immunizations, all of which, but for tetanus, are against communicable diseases, i.e. they are caught from those around us who are already infected and spreading the disease: 

•Required for kindergarten entry:

-5 DTaP (4 DTap if 4th is given on or after 4th birthday)*

-4 Polio (if 4th dose given before the 4th birthday, an additional age-appropriate inactive polio vaccine should be given

-4 MMR (measles, mumps, rubella)

-1 Varicella (chickenpox) or reliable history of having had the disease

•Required for 7th grade entry: 

  • 1 Tdap

  • 1 Meningococcal conjugate (MCV4)

•Required for 12 grade entry:

-2 Meningococcal conjugate vaccinations; only 1 dose, if 1st given after 16th birthday

* DPT, or DTaP, or Tdap are all immunizations against diphtheria, tetanus (lock jaw), and pertussis (whooping cough)

Fifteen years ago, I began seeing whooping cough cases for the first time in my professional life right here in Kennebec County. By being vaccinated against just diphtheria, tetanus (lock ja), pertussis (whooping cough), and small pox, my generation escaped diphtheria, whooping cough, and tetanus (which nearly killed an unimmunized farm boy in Oregon last year). When I was a boy, I recall adult neighbors pointing out houses where whole families were wiped out in a winter by diphtheria during the great depression in the 1930s; and as an intern in Seattle, I did, see some cases of it in unimmunized skid row residents. Small pox has been virtually eliminated now and we no longer immunize against it. Sure hope none of those come back!

Infants under age 2 are the most susceptible to whooping cough, especially under 3-6 months and if their mother’s immunity is low or absent. Those infants are too young to vaccinate and must rely entirely on either not being exposed, or breast milk and placental transfer of immunity. Half of those under 3 months with whooping cough require hospitalization and some die every year in the US. But even teenagers and adults suffer “the cough that lasts 100 days”. And they spread it to the unimmunized. Maine cases, usually fewer than 20-50/yr, have skyrocketed in the last few years (see first paragraph). 

Much of the concern of parents, who opt their children out of public school immunization requirements under the “philosophical” exemption, derives from a 20-year old controversy surrounding the MMR (measles, mumps, rubella) vaccinations; that controversy has been scientifically put to bed long ago (see below). But a change in Maine law 10 years ago allows parents to send children to school unimmunized if they have a “philosophical objection” to vaccines. Those children now constitute 4.6% of all children, while the religiously exempt remain under 0.4%, and the medically exempt (e.g. those with bad eczema, immune suppression, or other complicating conditions) about 0.3%. Maine’s opt out rate is one of the highest in the United States. In the best of circumstances, because of families moving in and out, it is impossible to get higher than 95% of children immunized at any one time, so an additional 4-5% opting out leads to a population barely 90% immunized and heading in the wrong direction. Most of these diseases, and clearly whooping cough, can continue and spread whenever 5-10% or more of the population is susceptible. The Maine legislature is debating tightening these rules again right now.

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National data for 2018 not yet available

Things have changed a lot since “the good old days”. Kids get many more vaccinations and because of that, many fewer serious illnesses. A good thing, since we have many fewer children around. When I started practice in Maine in 1972, the state had 25,000 births per year. Smaller family size has cut that number to around 12,500 now. Many medical risks have been reduced over these decades. Child car seats and safer cars have dramatically reduced traumatic injury and death for adults and children. Sunblock now prevents severe sunburn and its consequences. Medical advances save many more children and adults, who would have died in the old days. All these improved survivals have allowed more and more people to reach their old age, a “squaring off of the survival curve”, as epidemiologists call it when the survival curves look more and more like a rectangle than a right triangle (compare 1900 with 1997 in the graph). 


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A big part of this “squaring off” is due to improved immunizations against childhood diseases, eliminating that awful 20% mortality in the first 5 years of life one sees on the 1900 graph line. Diphtheria, whooping cough, tetanus shots (DPT) were first used in the military, then with school kids in the 1930s. So I, like others of my generation, didn’t catch those diseases but did suffer and survive mumps, chicken pox, German measles, and regular measles, still a major killer of young children in un-immunized developing countries. Mumps orchitis caused sterility in several of my male classmates in junior high. Chicken pox so scarred the lungs of a fellow medical intern when he was younger, that he never could walk upstairs without resting. And while German measles didn’t bother us kids much, it caused miscarriages and birth defects when mothers caught it for the first time when they were pregnant. Remember “rubella parties” to expose and thus immunize young teen girls? 

Then there were the really scary diseases, like polio; remember the March of Dimes? Public swimming pools would close when epidemics started, because it is spread by fecal (poop) contaminated water. Only 10% of the kids infected developed paralysis, but that was so devastating, all feared it. Also less well known but nearly as devastating were bacterial pneumococcal and Hemophilus influenzae infections of ears that then led to meningitis, pneumonias and abscesses. And most adults can probably still recall cases of meningococcal meningitis, killing young adults, especially those in high school or college or the military, mostly within just a few days. Bad stuff. All are now preventable with vaccinations; we docs almost never see these diseases anymore in this country.

Overall population resistance, or group immunity, is achieved when immunization levels exceed 90% and get closer to 95%. Why the reluctance of some parents to immunize? Many understandably also worry that the number of shots seems excessive. It certainly is more than our generation suffered. But the return in reduced illness and mortality is substantial. Other parents worry about the mercury preservative once used (thimerosal), but now removed from shots for those under 6, because it does cause more local reactions (sore arms). And an initial report in 1998 of 12 children who had autism after measles/mumps/rubella (German measles) shots, understandably frightened many. More extensive studies have since proved that connection wrong. The senior author of the 1998 paper was later sanctioned and his paper retracted when fraud, conflicts of interest, and data falsification emerged. Autism is a relatively newly recognized disease and continuing studies are attempting to identify its causes and treatments, but it seems pretty clear autism is not caused by vaccines. For instance, autism incidence has not declined despite the removal of mercury stabilizers. Further vaccine refinements have included changing the whooping cough vaccine to one devoid of any cellular material to reduce vaccine fevers. Many killed vaccines do still contain aluminum salts because they are benign and act as “adjuvants”, chemical enhancers of the immune response needed to protect.

So, how are our schools doing? Well, according to the Maine CDC, the Cape Cod Hill School’s kindergarten class in 2015-16 had 7% kindergarteners exempted without MMR vaccines, and 93% MMR immunized, whereas 3% of first graders were exempted. In 2018-2019, again 7% of kindergarteners were exempted and 93% MMR immunized (I can’t find first grade results). Small numbers, but worrisome trends. And our Franklin County is not doing so well as a whole (more on that next month). 

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It has been a long road from the days of many serious common diseases, to the present where immunizations offer significant protections, but only imperfectly unless all participate. If we are to live, work, and play together, we cannot allow immunization opt-outs, any more than we can allow driving on the wrong side of the road. Parents falsely hoping to protect their own children by avoiding vaccinating them appropriately, jeopardize the health of all of our children and all of us.