Last year, measles broke out in a Somali-American community in Minneapolis. When the dust settled, Minnesota had notched 79 cases of measles — the state’s largest outbreak in 30 years.
Twenty-one people, mostly children, were hospitalized. According to local media reports, fears that the measles-mumps-rubella (MMR) vaccine caused autism drove the slump in vaccinations from 92 to 42 percent in the community over 10 years as parents got exemptions for their kids.
Such outbreaks are examples of waning herd immunity, said Umatilla County Public Health Administrator Jim Setzer. When the majority of a group gets vaccinated, a virus can’t easily spread from person to person and unvaccinated people are generally protected, but herd immunity works only if most people get immunized.
Vaccinations are top of mind right now for Setzer because Wednesday is Exclusion Day, the day students whose immunization records aren’t current will be sent home from school. The county sent letters warning of potential exclusion to parents of 530 students on Feb. 5.
“Some of them aren’t up to date and others simply have incomplete records,” Setzer said. “We want to help them resolve this however it works for them.”
Last year on Exclusion Day, schools sent 147 students home. Parents have three options: get their children’s records to school, secure the required vaccines or file an exemption. Exemptions are either medical or non-medical.
Parents can qualify for non-medical exemptions by completing a 15-60 minute online class and print out a Vaccine Education Certificate. Many parents have done just that. Oregon’s non-medical exemption rate is one of the highest in the country. During the 2016-17, 6.7 percent of Oregon’s kindergarteners had exemptions for at least one vaccine. Despite that statistic, most Oregon schools have relatively few exemptions with only a small number of schools having extremely high rates, according to Stacy de Assis Matthews, the Oregon Health Authority’s school immunization law coordinator.
According to the Oregon Health Authority’s searchable database, for example, in the 2016-17 school year, most Umatilla and Morrow county schools had exemption rates of under 6 percent, including Sandstone Middle School in Hermiston (1 percent), McKay Elementary in Pendleton (3 percent) and Irrigon Elementary (1 percent). The Blue Mountain Mennonite School in Milton-Freewater was an outlier with 46 percent of students having non-medical exemptions for at least one required vaccine, according to the database.
De Assis Matthews defined “herd immunity.”
“If enough people in a population like a school are immunized, there’s a protective bubble around kids vulnerable to disease — the kids who are medically unable to be immunized,” she said.
According to the CDC, research has debunked anti-vaxxer claims that immunization leads to autism. Nine CDC-funded studies found no link. A mercury-based preservative called thimerosal was a major focus, but no relationship between thimerosal and autism was found. Thimerosal was phased out for other reasons by 2001.
“Immunization is the very best and safest way to protect children against vaccine-preventable diseases such as whooping cough and measles,” Setzer said. “Immunization helps keep our schools and community safe and healthy.
For the most part, most schools have healthy herd immunity.
“It appears that the non-vaccinated tend to cluster in particular schools or communities,” he said.
Like de Assis Matthews, Setzer worries about students with medical exemptions, those who can’t be vaccinated for health reasons such as cancer — they must rely on herd immunity to stay safe. Some, he said, describe healthy people who choose not to vaccinate as “epidemiological freeloaders.”
Setzer said parents who are unsure about their children’s immunization status may call Umatilla County Public Health (UCo) for help reviewing records. He encouraged parents to bring unvaccinated children to one of several special walk-in clinics in Pendleton (Feb. 20 and 21) and Hermiston (Feb 16 and 21). Call 541-278-5432 for more information.
“We’re all hands on deck,” Setzer said.
Pharmacists can give vaccinations to children, aged 7 and older.
For more information on required vaccinations, go to www.healthoregon.org/imm.
Contact Kathy Aney at firstname.lastname@example.org or 541-966-0810.