Supporters of Mainers for Health and Parental Rights carry boxes of signed petitions to the Secretary of State's office, Wednesday, Sept. 18, 2019, in Augusta. The group says they gathered more than 92,000 signatures in support of the People's Veto of government-mandated vaccine bill. Credit: Robert F. Bukaty | AP

AUGUSTA, Maine — The Maine election March 3 will not be limited to the Democratic presidential primary. Voters will also decide whether a new vaccine law will go into effect.

Question 1 — the only question on the ballot next Tuesday — concerns a law passed by the Legislature last spring that eliminated philosophical and religious exemptions for mandatory vaccinations. Here’s your guide to the campaign and how the law would work.

What does it mean to vote “yes” or “no”?

Question 1 will read as follows: “Do you want to reject the new law that removes religious and philosophical exemptions to requiring immunization against certain communicable diseases for students to attend schools and colleges and for employees of nursery schools and health care facilities?”

A “yes” vote is a vote to repeal the new vaccine law. If that side prevails, parents would be allowed to exempt their children from mandatory vaccines for religious and philosophical reasons. A “no” vote upholds the law, meaning parents would no longer be able to opt their children out of mandatory school vaccinations unless they had a medical exemption.

The new law, which has been placed on hold pending the outcome of the referendum, applies to children and others who attend public and private K-12 schools as well as colleges and universities and employees of nursery schools and health care facilities.

What’s the case for each side?

Supporters of the “people’s veto” referendum have made a range of arguments, with many saying the law infringes on religious and personal freedom and that children should not be prohibited from school for not having vaccinations. Many have also contended that vaccines are potentially dangerous, although the U.S. Centers for Disease Control and Prevention says the health risks are relatively small and outweighed by population-level benefits of disease prevention.

Opponents of the referendum, including doctors and medical groups, say vaccines are necessary to prevent the spread of preventable diseases. The bill was prompted by an increase in nonmedical opt-out rates in Maine over the past decade, reaching the sixth highest of any state for the 2018-19 school year, according to the CDC.

Public health officials say higher vaccine opt-out rates pose a threat to “herd immunity,” making it more likely that immunocompromised individuals will get sick. Maine has seen a return of contagious diseases — such as whooping cough and measles — over the past few years.

How did we get here?

The Maine Legislature passed the stricter vaccine bill largely along party lines last year. Prior to passage, the measure drew hundreds of Mainers to Augusta for a contentious day of testimony. Democratic Gov. Janet Mills, who signed the bill into law, opposes the referendum. If voters reject the referendum next week, the law will take effect starting in the fall of 2021.

There hasn’t been any public polling on this race, so it’s hard to gauge public opinion on the issue, but the vote is likely to be decided by a skewed electorate because it’s happening alongside the crowded Democratic presidential primary March 3, though any Maine voter can vote on the referendum.

Who is funding the campaign?

The Yes on 1 campaign, which raised $345,000 through Feb. 18, has largely been funded by individual donors, though it also received $50,000 from the Organic Consumers Association, a Minnesota-based anti-vaccine group that co-organized a yearslong campaign among the Somali population in Minneapolis to erode confidence in vaccines by highlighting a debunked link with autism. A 2017 measles outbreak in Minnesota almost entirely affected that community, according to the CDC.

A group opposing the referendum, an offshoot of Maine Street Solutions, a political consulting firm, raised more than $600,000. Most came from pharmaceutical manufacturers, including $500,000 alone from Merck and Pfizer. That fundraising has allowed the group to run TV ads, but it has also opened them up to criticism from the Yes on 1 campaign, which has tried to frame the referendum virtually from the beginning as a movement to “ reject Big Pharma.”

Maine Families for Vaccines, which has led the public-facing campaign to save the law, raised most of its money from individual donors as well as medical nonprofits such as the Maine Hospital Association.

Who will be affected by the outcome?

Families that want to opt their children out of vaccinations and individuals who cannot be vaccinated for medical reasons are the two groups of people that are likely to see the greatest effects from the outcome of the referendum.

A small percentage of Mainers cannot receive vaccines for medical reasons, often because they are allergic to an ingredient or already have a compromised immune system. To avoid catching vaccine-preventable diseases, these individuals rely on living in a community where most people are immunized, and face greater health risks when more people opt out of vaccines.

If the law stands, however, parents who oppose vaccinating their children for religious or philosophical reasons will have to decide between going along with mandatory vaccinations and potentially removing their children from Maine schools.

How have these stricter vaccine laws worked elsewhere?

Maine would be the fifth state to repeal all nonmedical exemptions. Beginning in 1900, Mississippi only permitted medical exemptions for school vaccines, though it added a religious exemption in 1960, though the state’s high court struck it down in 1979. It also has the highest vaccination rate of any state, with 99.2 percent of kindergartners fully vaccinated for the 2018-19 school year, according to the CDC. While some activists in the state have called for loosening the vaccine law, the effort has not gained momentum in the Legislature.

California eliminated personal and religious exemptions to vaccines in 2015 following a measles outbreak. While overall vaccination rates did increase, the effect was weaker than what lawmakers had hoped for, as the state saw an increase in the number of medical exemptions granted once personal and religious exemptions were no longer an option, according to a study published in the Annals of Internal Medicine. That led the state to pass another law last fall giving itself more oversight over medical exemptions.