BRAINTREE -- The coronavirus pandemic caused delays, postponements, and outright cancellations of all kinds of plans over the course of 2020, including the practice of going on pilgrimages. Now, as travel becomes safer, pilgrimage leaders are once again planning international trips while learning to adapt their plans to evolving circumstances.

Father Jurgen Liias, a senior priest in residence at St. Patrick Parish in Stoneham, has been trying to organize a trip to the Holy Land for 20 people. It was originally scheduled for November 2021, but it is now being postponed until February 2022 after failing to gain a minimum number of participants.

Father Liias has visited the Holy Land 15 times in the past 30 years and has also been to Turkey, Greece, and Poland. He called the Holy Land "the original and the supreme pilgrimage," where "your faith literally gets grounded."

"I love to teach the Bible, and there's nothing like teaching the Bible where it happened. You can stand in the spot and tell the story of what happened right there, and really imagine it much more fully," he said in a July 1 interview.

Typically, he said, a pilgrimage leader will work with a tour company to organize the trip and arrange a package deal based on the number of people who are expected to participate. The price usually varies depending on the size of the group: the fewer pilgrims, the more expensive it is overall.

While the coronavirus vaccine has enabled many people to resume travel and interpersonal activities, the virus still casts a shadow that complicates such plans. Different countries have different regulations for travelers, who also have to make decisions about what risks they are comfortable taking.

Regarding his pending trip to the Holy Land, Father Liias said Israel is being "very strict" about coronavirus regulations.

"The Israeli population has a pretty high percentage of people vaccinated. But it's more people coming from outside that they're concerned about. So that adds kind of a wrinkle and a complexity to the thing that we never had before," he said.

Currently, to enter Israel, one must show proof of vaccination. This means that some of the people who wanted to go on Father Liias' trip cannot participate, because they are not vaccinated and do not plan to be. To prevent travelers from simply presenting falsified documentation, blood tests are also required upon arrival.

Based on his years of experience, Father Liias said he usually aims to have a group of about 20 pilgrims, which he considers "a manageable number for a tour and pilgrimage." Postponing his trip to February of next year will allow a few more months for people to sign up, with a deadline around October.

"Hopefully, we'll get more people," he said.

Father Peter DeFazio, pastor of the South Boston Seaport Catholic Collaborative, had to cancel and reschedule a trip to Medjugorje several times over the last year. It was originally intended for the summer of 2020, then was postponed to the fall of 2020, then to May 2021. Now, they are planning the trip for Aug. 9-17.

This will be Father DeFazio's third time leading a pilgrimage to Medjugorje as a priest. He said it has a "very high" level of interest, and the Catholic Church has recognized that "wonderful fruit" is coming from people's experiences there. He has met priests who received their vocation and laypeople who returned to the faith because of Our Lady of Medjugorje.

Father DeFazio said many people who were originally signed up for the trip have decided not to go, out of concern for the rise of the delta variant of the coronavirus.

The pilgrims must show proof of vaccination and be tested for the coronavirus before leaving. Father DeFazio said they hope no other rules or requirements will be implemented before their departure.

Some pilgrimage leaders are waiting to see how the situation evolves before making plans.

Father Michael Nolan, pastor of St. Mary Parish in Waltham, runs the pilgrimage program for young adults Seven Miles From Jerusalem. He had planned to lead a pilgrimage to Jordan and Israel in May 2020 and another to Israel and Italy in January 2021, both of which had to be canceled.

Now, he said, they are in a holding pattern.

"It's not realistic to plan a pilgrimage for 2022 until we have more information. But I hope to as soon as possible," he said July 27.

He said the restrictions currently in place would force him to change the way he runs his pilgrimage in the Holy Land. Normally, his trip begins in Jordan and makes its way into Israel, tracing the history of the Old Testament before following the route of Christ's life. If they were to go now, they would have to fly directly to Israel instead.

All three priests noted the harsh economic impact of the pandemic on areas that are popular pilgrimage destinations. Much of the economy in Medjugorje and the Holy Land is based around tourism, and so have suffered greatly from pandemic travel restrictions.

"You shut down the tourist trade, and you have massive segments of the economy being shut down," Father Liias said.

Seven Miles From Jerusalem aims to help Christians living in the Holy Land by supporting Christian businesses and charities. Father Nolan said he thinks more pilgrims ought to go in order to support the economy there.

He said he is not giving up and will try to adapt and be ready to lead a pilgrimage as soon as possible.

"Even if I have a small group, I will go," he said.