The shutdown of Broadway’s 41 theaters will continue at least until Jan. 3, the industry’s leading trade group announced Monday. The action further extends the darkening of Broadway’s marquees that began March 12, as the covid-19 pandemic spread in hard-hit New York.

Though some new productions have revealed plans for April and May 2021 openings — including revivals of Neil Simon’s “Plaza Suite,” with Sarah Jessica Parker and Matthew Broderick, and “The Music Man,” with Hugh Jackman and Sutton Foster — few details have been made available about safety precautions that would make these events possible. In May, Actors’ Equity, the union for 51,000 professional actors and stage managers, said it is advising its members not to return to the stage until its own health and safety guidelines are met.

The Broadway League, which represents theater owners and producers, said on Monday that it was working with the theatrical unions and “key experts and some of the greatest minds inside and outside of the industry” on protocols that might aid the reopening effort.

“The Broadway experience can be deeply personal but it is also, crucially, communal,” Thomas Schumacher, president and producer of Disney Theatrical Productions and chairman of the Broadway League, said in a statement. “The alchemy of 1,000 strangers bonding into a single audience, fueling each performer on stage and behind the scenes, will be possible again when Broadway theaters can safely host full houses.”

The reference to safely hosting “full houses” indicates the current thinking on Broadway, that social distancing measures reducing the number of patrons is probably not conducive to economic success. Commercial productions in 1,000- to 2,000-seat theaters usually need to sell 90 percent of their tickets to be profitable.

Four nonprofits — Roundabout Theatre, Lincoln Center Theater, Manhattan Theatre Club and Second Stage Theatre — also maintain Broadway houses. While they, too, remain shuttered, they may have slightly more flexibility in audience size, given that part of their income comes from private donors.

The league has assembled several task forces to work out pandemic-related issues, including how to coordinate with city, state and federal officials over the health protocols for reopening. A Washington lobbyist has been retained by the league to act on Broadway’s behalf with the federal government, according to a league member who spoke on the condition of anonymity because they were not authorized to talk publicly.

The protracted shutdown most directly affects the approximately 87,000 jobs Broadway supports, according to the league. As a business that does $2 billion a year in ticket sales, and contributes about $575 million in tax revenue, Broadway is a significant contributor to New York’s economic health. About two-thirds of its patrons are tourists.

A shaky consensus has been building over the past few weeks that Broadway might be able to resume in the spring. But some industry insiders think that, without a vaccine for the novel coronavirus, that timetable might be overly optimistic. None of the long-running powerhouse productions have yet to say when they might start up again. In addition to “Plaza Suite,” which had a tryout run in Boston last winter and was to open in the spring, and “The Music Man” — originally scheduled to begin this fall — a few other postponed shows have announced new start-up dates.

“The Minutes,” a new play by Tracy Letts, a Pulitzer winner for “August: Osage County,” and a revival of David Mamet’s “American Buffalo” were scheduled for openings this past spring. Their producers recently announced tentative opening nights next March and April, respectively. Two of the nonprofits, Roundabout and Lincoln Center Theater, also revealed tentative plans: Roundabout has rescheduled its revival of Jeanine Tesori and Tony Kushner’s musical, “Caroline, or Change,” for spring 2021, and says it will proceed with director Diane Paulus’s new gender-inclusive revival of “1776” in the spring, as well. Lincoln Center Theater has reset the unveiling of a new musical, “Flying Over Sunset,” by Tom Kitt, Michael Korie and James Lapine, for spring 2021.

The league’s Monday announcement means anyone holding tickets to shows up to and including Jan. 3, 2021, will be entitled to a refund or exchange for a later date. According to the league, ticket holders will be receiving an email from “their point of purchase” with additional information. Anyone who does not receive an email by July 13 is advised to contact the ticket provider, the league added.