BOSTON -- Local election officials have been advised by the state's top election overseer to be vigilant about cleaning voting booths, swapping out pens shared by multiple voters and having extra poll workers on call as public health concerns over the spreading coronavirus collide Tuesday with the 1.85 million people expected to vote in the presidential primaries.

Secretary of State William Galvin said Monday that he does not think the virus, which has been confirmed in one patient in Massachusetts but has kicked off widespread concern about the risk of infection, will have any real impact on the elections but advised local clerks to be prepared all the same, and to make arrangements for voters who are self-quarantining themselves out of an abundance of caution.

"Obviously, we do not think it's a reason for people not to vote, but it has led to some concerns that are quite legitimate," the secretary said. "If you go through the process that average citizens will involve as a vote, they'll come to the table where they check in, they'll get a ballot which they will handle by themselves, they'll use a pen -- which usually is provided by the local election officials and may be used by multiple voters -- and then they will proceed to a compartment, mark the ballot and, having concluded that, will put it in the box."

First, Galvin's office suggested that each local election office maintain a list of volunteers who could be called in to assist at the polls in case the workers who are expected to staff the polling places ultimately decide not to report on Tuesday. He also proposed that poll workers make disinfecting each voting booth or compartment with sanitary wipes part of their routine.

"We're certainly supportive of that in any financial way we may need to be," Galvin said.

Recognizing that the pen used to mark a ballot is the item most likely to be shared by multiple people, Galvin's office suggested in a Monday morning email to all clerks in Massachusetts that each polling place keeps a stash of extra pens that can be swapped out regularly. He said voters could bring their own pen to the polls.

"The only caveat on that is please do not bring a red pen because the machines will not be read with the red pen, [the ballot] will have to be hand read," he said.

The secretary's office also gave clerks a heads-up on how to handle a situation in which a voter who has voluntarily secluded themselves out of concern about the coronavirus still wishes to cast a ballot on Super Tuesday.

"We recognize that's probably not a great number of persons. But there could be persons in Massachusetts who legitimately have that concern. We have advised local election officials for those persons who have self-quarantined and who would like to vote by absentee ballot, even though the law requires them to present themselves in person today if they would choose to do that, to treat them as persons who had been admitted to a hospital and allow them to absent ballot under that procedure."

The typical deadline to obtain an absentee ballot is Monday at noon, but using the procedure Galvin's office outlined for local clerks, any eligible voter who was admitted to a health care facility after noon on Thursday, Feb. 27, "can apply for an absentee ballot up until the polls close and ... can designate a person to hand-deliver the ballot to them."

"We're trying to be accommodating to citizens who are, hopefully in good faith, self-quarantining because they're concerned about their potential to spread the coronavirus," Galvin said Monday. "We're trying to adapt to that, we're suggesting to local officials they treat them that way. Do I think it's going to be a very large number? No, I don't."

Polls are open statewide from 7 a.m. to 8 p.m. Tuesday as Massachusetts is one of 14 states to hold their presidential primary contests on Super Tuesday.

In addition to voting for their presidential preference, voters in two House districts and two Senate districts plan to choose finalists to succeed former state representatives from Lunenburg and Taunton and former state senators from Plymouth and Westfield. Voters in Melrose will also decide the race to succeed that city's mayor, Paul Brodeur, in the House.

Galvin estimated Monday that 1.5 million Democrats and 350,000 Republicans will cast ballots in Tuesday's presidential primaries, a total on the Democratic side that would eclipse the Democratic turnout in the 2016 primary between Hillary Clinton and Vermont Sen. Bernie Sanders.

That works out to just over 40 percent of the 4.58 million eligible voters.

He said close to 230,000 people, including 190,000 Democrats, had already voted early last week, the first time the state has offered early voting ahead of a presidential primary contest.

The Democratic presidential primary has been a "twisting contest" that's seen a shift in the frontrunner position and a handful of candidates end their White House bids in recent days. On the eve of voting in Massachusetts, where 15 names will still appear on the primary ballot here, the field has been whittled down to a contest primarily between former Vice President Joe Biden, and U.S. Sens. Bernie Sanders and Elizabeth Warren, with former New York City Mayor Michael Bloomberg looming as a wild card. Sen. Amy Klobuchar dropped out of the race Monday, a day after Pete Buttigieg ended his campaign. U.S. Rep. Tulsi Gabbard remains in the race.

But absentee voters in Massachusetts who cast a ballot for a now-defunct campaign aren't necessarily locked into their selections ahead of Super Tuesday, Galvin said Monday.

Galvin on Monday morning outlined a situation in which someone who already mailed in their absentee ballot could show up at their polling place Tuesday and vote for a different candidate. The provision only applied to absentee voters -- Galvin stressed that all traditional ballots cast during last week's early voting period are final.

Absentee ballots can be returned as late as 8 p.m. Tuesday. But if a voter obtained an absentee ballot thinking they would be traveling on Election Day and then had a change of plans, that voter can bring their absentee ballot -- marked or unmarked -- to their polling place and exchange it for a fresh ballot that they would mark and submit in person.

Absentee ballots that have already been returned to a clerk's office are not opened or counted until Election Day, when they are processed at the absent voter's polling place. So if a voter who already sent in an absentee ballot has had a change of heart, he or she can vote for a different person if they can get to their polling place before their absentee ballot is processed.

"If you can get to the process before that happens, and John Smith shows up and shows obviously he's John Smith, if there's a question, and says, 'No, I don't want that absentee ballot, I want to vote in person,' and they can retrieve that absentee ballot so it doesn't go in the box, they give John Smith another ballot," Galvin said. "That's the only procedure that's left at this point."

Massachusetts has 4,581,319 voters who are registered to vote in Tuesday's presidential primaries, an increase of 309,484 people or 7.25 percent over the total ahead of the 2016 presidential primaries, according to data obtained from Galvin's office.

There are 1,491,600 registered Democrats (32.56 percent of all voters), 462,586 registered Republicans (10.1 percent) and another 2,564,076 unenrolled voters (55.97 percent) who can choose which ballot to pull when they show up at their polling place.