[imgcontainer] [img:pertussis-graph-2012-lg.jpeg] [source]CDC[/source] There has been an increase in the incidence of pertussis (whooping cough) in the past several years, and the greatest rates of increase have come in states where parents are allowed to exempt their children from immunization for religious or philosophical reasons. [/imgcontainer]

School nurses across rural America are busy preparing for the advent of influenza (“flu”) season, heightening awareness and promoting actions (including immunization) to prevent the spread of flu in their communities.

But for school nurses in Vermont, the work of fulfilling an added burden handed to them by the state legislature earlier this year is just beginning, as they work to complete complex assessments of student immunization records that must be reported to state officials by January 1.

This is a result of Vermont’s Act 157, a law, like so many others, that originated with the best of intentions. 

The law was passed this year in response to declining immunization rates. Fewer people were vaccinating their children, a situation not unique to Vermont, the nation’s most rural state. Stories about declining immunization have come in from across rural America.

But the declines come in the midst of a pertussis (whooping cough) outbreak the likes of which Vermont has not seen in years, if ever. 

What, if any, is the relationship between these two phenomena, the whooping cough outbreak and the declining rates of immunization? It may be hard to pin that down, but let’s start by reviewing the Vermont legislation.

Measuring immunization coverage is a tricky business. By any measure, however, Vermont had tumbled from the #1 spot (in the percentage of children immunized) to near the bottom of the heap in recent years. 

Thus, it might have seemed a natural for the legislature to consider a bill that would remove the option for kids to remain in school if the parents and guardians harbored “philosophical convictions opposed to immunization.” 

As the legislative debate was heating up in February 2012, the National Conference of State Legislatures reported that while all 50 states have legislation requiring certain vaccines for students, and all such laws allow exemptions to the recommended vaccine schedules when medically indicated, only 20 states (Vermont among them) permitted “philosophical exemptions for those who object to immunizations because of a personal, moral, or other beliefs.”

[imgcontainer left] [img:6a00d8341c630a53ef0133efe0a38d970b-300wi.jpeg] With vaccination, the nation cut back the number of whooping cough cases to near zero. But then vaccination rates went down and the number of pertussis cases increased. [/imgcontainer]

A legislative strategy might reasonably be viewed as one tool in the effort to increase U.S. vaccine coverage rates. In the state of Washington, where a whooping cough epidemic was declared on April 3, 2012, a law tightening the rules for opting out was passed in 2011, and many are watching to see whether that requirement impacts the state’s vaccine exemption rates.

The Vermont bill passed the Senate easily, and that’s when the fun began. 

State health officials and health care providers were passionate in their advocacy for vaccination. After all, vaccination was included by the Centers for Disease Control and Prevention (CDC) in its list of the Ten Great Public Health Achievements of the 20th century. In publishing this list, the CDC referenced the impact of vaccination on the eradication of smallpox; elimination of poliomyelitis in the Americas; and control of measles, rubella, tetanus, diphtheria, Haemophilus influenzae type b, and other infectious diseases in the United States and other parts of the world.

But nothing like an element of personal choice to galvanize the opposition (and negate science): enter the Vermont Coalition for Vaccine Choice, whose motto is “Vaccination Choice is a Human Right.” 

After days of heated testimony as the bill made its way through multiple committees, and in a classic last-minute scramble of legislative sausage making, Act 157 emerged with the philosophical (and religious) exemptions intact. As long as parents/guardians annually provide a signed statement to the child’s school, they would be allowed to exempt their children from immunization. 

Parents would be required to certify their religious beliefs or philosophical convictions opposed to immunization. And they would have to show that they had read and understood educational material provided by the health department. (This included information about the increased risks to both those who are unvaccinated and to those who may be unable to receive vaccinations because of medical conditions of vaccine preventable diseases, such as whooping cough and measles.)

[imgcontainer] [img:K+vax+coverage+2011-2012.gif] [source]CDC[/source] This map shows the estimated percentage of children enrolled in kindergarten who have been exempted from receiving one or more vaccines in the 2011–12 school year. You can compare this map to the one at the top of the story to see that states with large numbers of exemptions are also the states where whooping cough is making a comeback. [/imgcontainer]

Act 157 also added to the complexity of the annual school reporting on immunization coverage rates by increasing the number of grades at which this data must be reported. In Vermont this work is largely conducted by school nurses, who already have arguably one of the most difficult jobs on the planet, especially now that there are such clearly established linkages between students’ health and academic achievement.

Which brings us back to a rise in the number of confirmed cases of pertussis, or whooping cough, across the U.S., with Vermont smack in the midst of an ongoing outbreak.

A comparison between states with low vaccination coverage rates and those reporting higher numbers of whooping cough cases shows some, though not consistent, overlap. Consider the following map from the CDC reflecting kindergarten exemption rates from the 2011-2012 school year:

Exemptions might not reflect a child’s vaccination status. Children with an exemption who did not receive any vaccines are indistinguishable from those who have an exemption but are up-to-date for one or more vaccines. U. S. Centers for Disease Control and Prevention (CDC)

Vermont (#3) and Washington (#6) rank near the top of the list in these kindergarten exemption rankings. Contrast that with the map below on which the darkest states represent those with the greatest increase (either two to three fold or greater than three fold) in the reported number of cases of pertussis between 2011 and 2012.

Sixteen of the top 20 states on the CDC’s list of those with an incidence of pertussis the same or higher than the national incidence (about 9 per 100,000 persons as of September 20, 2012) are states with the highest kindergarten entry vaccine-exemption rates. Washington and Vermont occupy the 3rd and 5th spots on this top 20 list respectively, and both have kindergarten exemption rates that are greater than 4 percent.

And finally, here is how the philosophical and religious exemptions map out, according to the Institute for Vaccine Safety at the Johns Hopkins Bloomberg School of Public Health (July, 2012).

[imgcontainer] [img:Inst+Vax+Safety+map.gif] [source]Institute for Vaccine Safety at the Johns Hopkins Bloomberg School of Public Health [/source] Here are the states and their allowed exemptions to vaccination laws. [/imgcontainer]

In states like California and Washington, exemption rates may vary widely across the state and reflect clustering at the county level, sometimes corresponding with higher socioeconomic and educational levels. This clustering increases the risk of disease outbreak in those communities.

Like so many things in medicine these days, “it’s complicated,” and public health officials are careful to point out that while they disagree with opting out of recommended vaccines for non-medical reasons, exemption is not the only phenomenon that is driving the current and substantial increase in pertussis cases across the country. 

As discussed in Jane Brody’s Personal Health New York Times blog (“Whooping Cough: A Stealthy Illness”), even individuals who have been fully vaccinated against pertussis (given in combination with diphtheria and tetanus vaccines, known as DTaP or Tdap) are not completely protected against disease. Research is beginning to show that immunity from the vaccine may not be as long lasting as originally thought. 

But experts do agree that pertussis vaccine remains the single most effective approach to illness prevention. Moreover, vaccinated children who get whooping cough tend to have milder illness. 

Because very young infants are among the groups at greatest risk for life-threatening disease, and are too young to be protected by vaccines that they can only begin to receive at two months of age, their protection depends on immunizing the people around them. 

Thus, the CDC now recommends a pertussis-containing booster shot for teens and adults who have not had one, and this recommendation is being given special emphasis for pregnant women and anyone who has routine contact with infants — siblings, grandparents and other relatives, babysitters, and health and child care providers.

Parents want to do what’s best for their children, and this motivation in part results in opposition to recommended immunization schedules, mistrust of vaccine science, and suspicion toward the pharmaceutical industry and government involvement in health policy. 

Clinicians and public health officials must continue to find ways to participate in respectful conversations and provide credible information in response to questions about vaccine safety. Inevitably in this particular dialogue, it comes down to whether we allow parents to opt out of vaccinating their children based on their own risk evaluation, thus diminishing the benefit to community and jeopardizing the health of others—especially the medically vulnerable and the very young. 

Meanwhile, Vermont is rewriting its immunization regulations to reflect the state’s recent legislation. How all of this will “sugar off” remains to be seen — perhaps not until the results are in from this year’s school nurse data collection, about the time the sap is beginning to boil. 

If the current disease trend is any indication, there will still be plenty of coughing in the classroom by the time that happens.

Dr. Wendy Mahoney is a Vermont physician.

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