Andy Tullis / The BulletinSeventh-grader Jake Severson, 12, gets vaccinated Wednesday against tetanus, diphtheria and pertussis (whooping cough) by Marylou Paterson, a registered nurse for Bend-La Pine Schools, at Ensworth Elementary School in Bend. Deschutes County had seven cases of whooping cough in 2013 and three in 2012, when the state as a whole had more than 900 cases, the most since 1953.

WASHINGTON — With a new law going into effect next month that requires parents to speak with a medical provider or watch an interactive online video before they can opt out of vaccinating their kindergartners, Oregon is joining its West Coast neighbors in making nonmedical exemptions harder.

The current law was still in effect last Wednesday, this year’s school exclusion day when schoolchildren must show documentation that they are up-to-date on their immunizations or show a medical or religious exemption. In order to claim a religious exemption, parents had to sign a form, which a recent study of state immunization laws characterized as a relatively easy exemption procedure.

In an article published this month by the Journal of the American Medical Association, lead author Saad Omer, a professor at Emory University, noted that the vast majority — 31 out of 36 — of immunization exemption-related bills introduced in 18 state legislatures between 2009 and 2012 tried to make it easier to get a nonmedical exemption, or NME. But none of them was enacted into law.

Three of the five bills that made it harder to obtain an NME did become law: in Washington, California and Vermont.

Oregon’s new law was introduced after 2012 and was not included in the study.

At 6.4 percent, Oregon had the highest NME rate for kindergartners in the country last year. Deschutes County (8.1 percent) is one of nine counties in Oregon above 8 percent.

Parents who have previously opted for a religious exemption for their children will be grandfathered in under the new law, said Stacy de Assis Matthews, school law coordinator at the state’s Oregon Immunization Program.

The new law allows for exemptions on religious, philosophical or personal grounds, and includes an educational requirement. Prior to being granted an NME, parents must either discuss vaccination options with a health care practitioner and get a parent signature on a vaccine education certificate, or watch an interactive module online and print out a completion form.

“The goal is to make sure kids are fully protected against vaccine-preventable diseases,” Matthews said.

While vaccines are designed to protect an individual from contracting a certain disease, the spread of contagious diseases can be suppressed when a high enough percentage of the population has been vaccinated. This is often called herd immunity, in which the population’s collective immunization helps limit everyone’s exposure to potentially dangerous diseases.

The Centers for Disease Control and Prevention recommend an immunization regimen for children up to age 6 for the following diseases: chickenpox, diphtheria, hib, hepatitis A and B, flu, measles, mumps, pertussis (whooping cough), polio, pneumococcal, rotavirus, rubella and tetanus (lockjaw).

The percentage of immunized individuals required to provide herd immunity varies for each disease. For mumps, diphtheria and rubella, health professionals prefer 85 percent immunization, while for measles and pertussis the number approaches 94 percent.

“The concern here is that a highly contagious disease could be introduced to a school that doesn’t have a high immunization rate, and that students could get sick,” Matthews said. “If there are enough people immunized against a disease, it helps protect people who can’t be immunized.”

Infants are the most vulnerable to disease because they haven’t had the time to build up full immunity, even if they are up-to-date on their shots, she said.

Whooping cough is of particular concern in Oregon. In 2012, more than 900 Oregonians contracted whooping cough, including three in Deschutes County, the most cases statewide since 1953, according to the Oregon Health Authority’s Public Health Division. Infants have the highest infection rate, and they are most likely to suffer complications. Since 2003, five infants have died from pertussis in Oregon.

Between 1998 and 2001, the incidence rate for pertussis in Oregon hovered around the national average, at or near 3.0 cases per 100,000 people. But in 2002, Oregon’s rate began increasing rapidly, from 5.5 to 12.4 in 2003, plateauing above 17 in 2004 and 2005. National rates climbed during that period, also, but not nearly as steeply as Oregon. The national rate reached 8.7 and 8.6 in 2004 and 2005 before dropping back to 3.5 in 2007.

In 2012, Oregon’s rate of 23.3 cases per 100,000 was almost twice as high as the national average of 13.2, and more than four times higher than it had been a decade earlier.

In an article published last year in Pediatrics, the journal of the American Academy of Pediatrics, lead author Jessica Atwell examined the 2010 pertussis outbreak in California, which led to 10 deaths. Atwell concluded that areas with high rates of nonmedical exemptions were associated with high rates of pertussis cases.

“Our findings suggest that communities with large numbers of intentionally unvaccinated or undervaccinated persons can lead to pertussis outbreaks,” she wrote. “In the presence of limited vaccine effectiveness and waning immunity, sustained community-level transmission can occur, putting those who are most susceptible to communicable diseases, such as young infants, at increased risk.”

The educational requirements in Oregon’s new law are similar to those in Washington’s law, which went into effect in 2011 and requires a health care provider’s approval for any type of exemption. In 2009, 7.6 percent of Washington’s kindergartners claimed a nonmedical exemption, the highest rate in the country. Since the law was passed, the percentage of kindergartners claiming an exemption has dropped to 4.6 percent last year.

In 2012-13, the percentage of Washington kindergartners vaccinated against pertussis climbed to 92.4 percent, a 1.5 percentage point increase from the previous year, according to the Washington State Department of Health.

— Reporter: 202-662-7456, aclevenger@bendbulletin.com