Following a pair of measles outbreaks earlier in the year, Seattle public schools ban students without vaccination from attending.

The deadline for vaccination is January 8.

Previously, the school district allowed exceptions for specific cases based on religious or philosophical grounds. However, 87 confirmed cases of measles across the state of Washington prompted a more hardline approach. Seattle Public Schools banned such exemptions. Now, an estimated 2,000 students require vaccination in order to attend class beyond the January 8 deadline.

The United States experienced the most outbreaks of measles this year since 1992. As a result, a number of states implemented similar measures to Washington in an effort to stem the spread. For example, New York passed legislation banning exemptions for students attending both public and private schools.

Vaccination Skepticism Driving Outbreaks

As reported by Vox, the states with the greatest number of cases are New York, New Jersey, Washington, and California. The majority of all cases in the US arose within Orthodox Jewish communities in New York where parents opt out of vaccination for their children in greater frequency.

Despite eliminating measles in the US in 2000, the surge indicates an underutilization of vaccines. Other countries suffer far harsher outbreaks, many for weak healthcare or lack of access. Cases surge, then spread via travelers across the globe.

When the vast majority of Americans received vaccination, travelers carrying the disease posed little threat to the populace. However, with growing pockets of unvaccinated individuals, the tide turns.

The director for the Center for Disease Control, Robert Redfield, advocates for vaccination for all. “Measles is preventable and the way to end this outbreak is to ensure that all children and adults who can get vaccinated, do get vaccinated,” he said in a statement.