Wednesday, February 18, is School Exclusion Day in Oregon, when students without up-to-date documentation verifying immunizations or an official exemption will be sent home from schools and child care facilities.

School Exclusion Day always falls on the third Wednesday in February, but this year it does so with new legislation taking effect. Senate Bill 132, which passed in 2013, requires parents seeking nonmedical exemptions to vaccinations to receive medical information on vaccinations’ benefits and risks from either a health care practitioner or an online education module. Students whose parents had already filed nonmedical exemptions before March 1, 2014, are not affected by the new law. These students were in effect “grandfathered in,” says Stacy de Assis Matthews, school law coordinator for the

Public Health Division of Oregon Health Authority.

State Sen. Elizabeth Steiner Hayward (D-Beaverton) has introduced legislation that would end the grandfathering and require the all parents claiming nonmedical exemptions go through the new process. According to the senator, Bill 442 takes a “half step” in its current state. However, she is nowhere close to finished with the issue.

Steiner Hayward says she intends for Bill 442 to be “gutted and stuffed” to include a section that would remove the nonmedical exemption option, which allowed the parents of 9.6 percent of Multnomah County kindergartners to opt their child out on one or more recommended immunizations last year.

If Bill 442 is revised and passes that way, Oregon would be the third state in the country to allow exemption only for medical reasons, joining West Virginia and Mississippi. Steiner Hayward, a physician at Oregon Health & Science University, has been a vocal supporter for raising the state’s vaccination rates, which are often described as the lowest in the nation: “I’m a science person,” she says. “And the science around vaccines is crystal clear. Vaccinations are highly effective when used correctly, and the diseases that they prevent are very, very dangerous.”

Yet according to Matthews, simply stating that Oregon has the lowest vaccination rate in the nation is misleading: “That stat is based on a grouping of kindergartners with one or more vaccine exemptions,” she says. “If you look at the data behind each individual vaccine, Oregon is not the lowest.”

Many major health officials (such as the NIAID and the Oregon Health Authority) agree that reaching the vaccination rate required to achieve community immunity (or “herd immunity”) is important for preventing infectious disease from spreading among a population. Achieving herd immunity is especially key for protecting immunocompromised individuals who are unable to receive vaccinations for medical reasons. A recent Oregon Live article reported concern from health officials about Oregon rates for specific vaccinations, such as the one against measles, mumps, and rubella.

Bill 442 has not yet passed the state senate—you can keep an eye on its progress here. In the meantime, will the new nonmedical exemption process affect the rate of vaccination among Oregon’s kindergartners, as parents are legally required to receive science-based information about the pros and cons of vaccination? Matthews says that the data necessary to answer that question will be available in May.