Calls for vaccine mandates against COVID-19 — both in the corporate world and beyond — have gained increasing momentum in recent months.

Some companies have cited the highly-transmissible delta variant as reason for the change, with coronavirus hospitalizations surging again as the strain rages across the country. 

The U.S. is reporting an average of around 137,000 new cases per day, an increase of about 12% from the previous seven-day rolling average, CDC director Rochelle Walensky said Tuesday. Unlike other points in the pandemic, hospitals now have more non-COVID patients for everything from car accidents to surgeries that were postponed during the outbreak.

Other companies waited for the Food and Drug Administration's full approval of Pfizer's COVID-19 vaccine before mandating vaccines for workers. That approval came on Aug. 23 and sparked another flurry of vaccine requirements, with some experts predicting similar mandates will continue to gain popularity in the coming weeks and months.

Here are some companies requiring employees get vaccinated against COVID-19:

Nationwide train service Amtrak will reportedly require all employees be vaccinated against COVID-19 by Nov. 1, or face mandatory weekly testing, an Amtrak spokesperson confirmed to Spectrum News.

Starting Oct. 4, all new hires will also be required to show proof of vaccination. 

“We did not come to these decisions lightly, and we understand it may take some time to process, which is why we are providing you with time to prepare,” Amtrak CEO Bill Flynn reportedly told employees in a memo obtained by multiple news outlets. “While we recognize this is a personal decision for each of us, we are confident it is in the long-term best interest for our colleagues, our customers and our company.”

AT&T on Thursday all management employees going back to in-office work must be fully vaccinated against COVID-19 by Oct. 11 at the latest. 

“Since the global pandemic began early last year, our employees’ health and safety has been a top priority,” a company spokesperson told Spectrum News in an emailed statement. “Given the recent surge in the Delta variant, we are taking additional steps to help ensure the safety of our employees and customers, and provide for effective business continuity in what is a dynamic and uncertain environment.”

All employees will be required to wear masks, regardless of vaccination status. AT&T will also begin discussions with its union partners to agree on a path forward for union-represented employees.

Barclays Center, home of the Brooklyn Nets, announced Friday that all guests and employees will soon have to be fully vaccinated before entering the premises. 

Starting on Sept. 13, individuals 12 years and older must provide proof that they have received at least one COVID-19 shot.

“We have heard from our fans that requiring vaccination is important to them and we want to provide the safest possible environment for all employees and guests at Barclays Center,” a company statement read in part. 

All attendees and employees must continue to wear masks, regardless of vaccination status, unless eating or drinking.

One of the world's largest cruise lines is now requiring COVID-19 vaccinations for most passengers sailing from ports along the Atlantic or Gulf coasts.

Carnival Cruise Lines announced Monday that starting Aug. 28, cruise guests over the age of 12 will now need to be fully vaccinated against COVID-19, unless they have a medical condition that does not allow them to be vaccinated. Guests must provide proof of age or medical exemption at the time of check.

Carnival said the vaccine requirement is needed because more places are changing regulations for cruise ships sailing into ports outside the United States.

"Given the number of itineraries that include multiple destinations throughout the Caribbean and, in particular, in The Bahamas, and the need for us from time to time to adjust itineraries due to medical, technical or weather emergencies, we will now operate all sailings under this requirement," a statement on the Carnival website read.

The Bahamaian government announced last week that any ship wishing to enter a port in The Bahamas must confirm that all guests 12 and older are fully vaccinated, aside from anyone with a medical exemption. 

The decision will be an especially big change in Florida, which has some of the busiest cruise ports in the world.

Florida Gov. Ron DeSantis banned vaccine passports and refused to allow an exemption for the cruise industry. Norwegian Cruise Line sued the state over the ban, threatening to pull out of Florida ports if it continued to stand. A federal judge temporarily blocked the vaccine passport ban, but the state is appealing the ruling.

Following the FDA’s full approval of Pfizer’s COVID-19 vaccine on Monday, CVS Health announced that certain customer-facing employees must be fully vaccinated against the deadly virus.

“From the start of the pandemic, our decision-making process has been driven by health, safety and science,” CVS Health president and CEO Karen Lynch wrote in a statement. “While the vast majority of our employees have chosen to be vaccinated, this decision is in direct response to the dramatic rise in cases among the unvaccinated.”

Roles that require proof of vaccination include nurses, care managers, some pharmacists and corporate employees, which must be completed by Oct. 31. Individuals hired for the same roles after Sept. 15 will be required to have received at least one dose of a COVID-19 vaccine prior to their first day of work. 

Pharmacists working at CVS retail stores will have until Nov. 30 to get vaccinated, due to the “size of this employee population.” Other roles at CVS Health may be required to get vaccinated in the future pending review of public health information.

Deloitte announced they will require all U.S.-based employees to be fully vaccinated against COVID-19 before returning to the office, with CEO Jon Ucuzoglu citing the Food and Drug Administration’s recent full approval of the Pfizer vaccine as reason for the change. 

“Further, over the past several weeks, we gave seen a number of clients, as well as several cities and states, impose restrictions on the ability of those who are unvaccinated to access offices and other public locations,” Ucuzoglu wrote in a letter emailed to employees on Tuesday, which was obtained by Spectrum News. “The ability to participate in the broader business ecosystem will be increasingly challenging for those who are not vaccinated.”  

The mandate will take effect on Oct. 11, seven weeks after the FDA granted full approval of Pfizer’s vaccine. The company previously announced that individuals attending in-person meetings at Deloitte University must be vaccinated by Sept. 7, although onsite participation is optional based on comfort level and travel schedules.

While the Walt Disney Company mandated vaccines for its U.S. employees in early August, Disney Cruise Lines announced Tuesday that guests will also be required to be fully vaccinated before stepping aboard a ship.

For cruises starting Sept. 3 that include a stop in The Bahamas, guests ages 12 and older must be fully vaccinated 14 days before leaving on the ship. Guests must also provide a proof of vaccination before leaving.

Guests under 12 must provide a negative COVID-19 PCR test taken between 5 days and 24 hours before the sail date.

The change in policy coincides with The Bahamas government's order requiring all cruise ships to provide crew and passenger manifests showing everyone is fully vaccinated prior to entering port.

Disney says this ruling includes any cruise line private islands in The Bahamas, including Disney's Castaway Cay. All of Disney's Florida-based cruise itineraries for the fall include a stop at Castaway Cay, making the vaccine requirement necessary for all Florida cruises.

DoorDash will require all corporate employees be vaccinated against COVID-19, a spokesperson confirmed to Spectrum News on Thursday.

The company is currently operating under a work-from-home policy, with select offices in the U.S. open for those who choose to go in. DoorDash will transition to a hybrid work model for corporate employees next January, with only 5% of the total workforce expected to work in an office every day, per a blog post shared last week

"In June 2021, we internally announced that where permissible by local law, any corporate employee voluntarily returning to one of our U.S. corporate offices in 2021 must be fully vaccinated against COVID-19," the spokesperson said in an email. "We haven't issued any official vaccination requirements for Dashers, given they're not employees."

Luxury workout brand Equinox Group — the company that owns Equinox gyms and Soul Cycle — will require customers and corporate employees to show a one-time proof of vaccination, starting with their New York locations in September. 

Customers and employees can prove their vaccination status in three ways: With a physical CDC immunization card, a photo of the immunization card, or a digital vaccine card such as New York’s Excelsior Pass. 

"We have always made the health and safety of our communities our top priority, and we will continue to do so in partnership with infectious disease experts as well as local governments," Harvey Spevak, Equinox Group Executive Chairman, wrote in a statement in early August. "We have a responsibility to take bold action and respond to changing circumstances with urgency. We encourage other leading brands to join us in this effort to best protect our communities."

Equinox says it will “introduce similar policies in all of its markets” as demand for in-person experiences grows.

Facebook will require all employees at U.S.-based offices to get vaccinated before returning to work, the company’s vice president of people, Lori Goler, announced in a statement on Wednesday.

"How we implement this policy will depend on local conditions and regulations,” Goler added. “We will have a process for those who cannot be vaccinated for medical or other reasons and will be evaluating our approach in other regions as the situation evolves. We continue to work with experts to ensure our return to office plans prioritize everyone's health and safety.”

Frontier on Friday became the second major domestic airline to announce it will require all “direct employees” to be vaccinated against COVID-19, citing the rapidly spreading delta variant as reason for the mandate. 

“As we continue to watch the rapid increase of new COVID-19 cases across the United States caused by the Delta variant, I am concerned for the well-being of our team members, their families and friends,” Frontier Airlines president and CEO Barry Biffle, wrote in a statement. 

“The good news is that the vast majority of our employees have already taken this important step and have gotten vaccinated,” Biffle added. “I hope the step we’re announcing today will further increase the percentage of our workforce that’s fully vaccinated.”

Employees have until Oct. 1 to comply with the mandate. Those who do not wish to get vaccinated or have a religious or medical exemption must submit to weekly COVID-19 testing.

The U.S. nursing home industry’s biggest player announced this week that its employees must get a COVID-19 vaccine to keep their jobs.

The new requirement at Genesis Healthcare, which has 70,000 employees at nearly 400 nursing homes and senior communities, is the clearest sign yet that owners may be willing to risk an exodus at already dangerously understaffed facilities to quickly vaccinate the 40% of workers still resisting shots and fend off the surging delta variant.

All current employees, personnel, care partners and vendors must comply with the requirement by Aug. 23. 

"Our move to adopt universal vaccination is an incredibly important decision, and we very seriously weighed the competing concerns before proceeding down this path," a statement on the company's website reads in part. "While we would have greatly preferred a strictly voluntary process, our commitment to health and safety outweighs concerns about imposing a requirement. We have concluded that this approach provides the safest and most effective course of action to ensure the health and welfare of our patients, residents and staff."

Hours before Facebook’s announcement, CEO of Google and Alphabet Sundar Pichai penned a blog post similarly saying all employees would be required to be vaccinated against COVID-19 before returning to the office. The policy will be rolled out in the U.S. in the coming weeks, and will expand to other regions in the months to follow. 

“The implementation will vary according to local conditions and regulations, and will not apply until vaccines are widely available in your area,” Pichai wrote in part. 

The company also announced it would be extending its optional work-from-home policy through at least Oct. 18, pushed back from a previously-proposed return-to-office date in mid September. Pichai noted that many employees are “seeing spikes in their communities caused by the Delta variant and are concerned about returning to the office.” 

“This extension will allow us time to ramp back into work while providing flexibility for those who need it,” Pichai added. “We’ll continue watching the data carefully and let you know at least 30 days in advance before transitioning into our full return to office plans.”

Health insurance giant Humana announced Thursday it will require full COVID-19 vaccinations for associates and select contractors who conduct work outside of their homes on behalf of the company. Director of Corporate and Financial Communications Mark Taylor said the move is "a result of the ongoing rise in infection rates of COVID-19 and its variants."

"Throughout the COVID-19 pandemic, Humana has remained steadfast in our collective promise to put health at the center of everything we do, with the safety of our associates, members and communities as our top priority," Taylor said in an email. "And as a leader in health care innovation and community wellness, we’ve set high expectations for ourselves to deliver on that promise."

The requirement applies to those who work within Humana facilities, interact directly with members and patients and/or attend in-person meetings or training, Taylor said. It will take effect when the first vaccine receives full Food and Drug Administration approval. After that approval date, associates and select contractors will have 60 days to provide proof of full vaccination.

Popular ride-sharing service Lyft will require corporate employees to provide proof of vaccination before returning to the office, a spokesperson confirmed in an email to Spectrum News.  

Lyft "informed team members several weeks ago that they will be required to submit proof of vaccination in order to return to the office," the spokesperson wrote in part, adding: "We have a process in place to handle accommodations and exemptions for team members who have medical, religious or other personal reasons for not receiving the vaccine." 

According to Lyft's website, the company is not mandating a COVID-19 vaccine for drivers or riders, but is "encouraging" them to do so. 

The company also pushed back its in-office reopening date by six months to Feb. 2022.

Chicago-based fast-food giant McDonald’s will require all U.S.-based office employees be vaccinated against COVID-19 by Sept. 27 in an effort to protect employees from the highly-transmissible delta variant, according to an internal note obtained by Spectrum News.

The news was first reported by the New York Times and the Wall Street Journal on Wednesday. 

Corporate offices will also not reopen until October so that employees have ample time to receive their jab. 

“A resurgence of infections caused by Covid-19 variants has many of us uneasy,” the statement read in part. “We’ve heard from many of you that you would feel more comfortable returning to the office if you had more certainty your colleagues were vaccinated.”

All employees must also continue to wear masks regardless of vaccination status for the time being. The company announced in January that employees would be given four hours of paid time off to get their jab.

MGM Resorts International employees in Las Vegas will be required to get a COVID-19 or pay for routine testing in order to go to work, according to multiple local news outlets. 

Unvaccinated employees will be required to pay $15 for an on-site COVID-19 test, or can show proof of a negative FDA-approved, molecular PCR test from an offsite testing location. Results from antigen or home-testing kits will not be accepted.

Employees who are vaccinated can upload their vaccine card to the MyMGM app in order to receive a verification sticker needed for in-office work. 

“As of July 26, Covid-19 testing will transition to an ongoing cadence and any Las Vegas employee who is not designated in Workday as ‘Home Office’ for their location and does not have a vaccine verification sticker will be required to participate,” an MGM spokesperson told 8 News Now.

Microsoft will reportedly soon require all employees, vendors and guests entering U.S. campuses be vaccinated against COVID-19. 

“As we have done since the beginning of the pandemic, we continue to closely track new developments and adapt our plans as this situation evolves, keeping employee health and safety top of mind," a company spokesperson confirmed in an emailed statement to Spectrum News, later adding: "...Starting in September, we’ll also require proof of vaccination for all employees, vendors, and any guests entering Microsoft buildings in the U.S., and will have an accommodation process in place for employees."

"We continue to review the situation on a local basis in each region/country/state where we work and will adjust dates and policies as needed," the statement added.

Individuals will be asked to show proof of vaccination starting in September, although the company also recently pushed back its office reopening date from Sept. 7 to no earlier than Oct. 4.

NBC Universal will require all U.S. employees to be fully vaccinated against COVID-19 before returning to in-office work this fall, EVP Adam Miller said to employees in an emailed statement on Aug. 11.  

Employees will be required to prove their vaccination status, and the company has pushed back its full office reopening date from Sept. 13 to Oct. 18.

“Recent developments, including the rise in regional positivity rates due to variants and breakthrough cases, and guidance from medical experts and authorities have led us to the conclusion that we need to alter our approach,” Miller said in the email, which was obtained by the Wall Street Journal. 

Vaccinated employees can return to the office on an at-will basis until Oct. 18 at the earliest, Miller added.

Pfizer, the company responsible for one of three emergency-approved COVID-19 vaccines available in the states, will reportedly require all of its U.S. employees to either get their own jab or participate in weekly testing. 

The move is intended to “protect the health and safety of our colleagues and the communities we serve,” Pfizer spokesperson Pamela Eisele said in a statement first obtained by Reuters. 

“Outside the U.S., the company is strongly encouraging all colleagues who are able to do so in their countries get vaccinated,” Eisele’s statement continued. “Colleagues who have medical conditions or religious objections will be able to seek accommodations. Colleagues are still required to adhere to all COVID-19 state, local and Pfizer safety procedures while engaged in Pfizer work.”

Spectrum News has reached out to Pfizer for comment.

In a similar move to Disney Cruise Lines, Royal Caribbean recently updated their COVID-19 policies to mandate all guests over the age of 12 be fully vaccinated against the virus on any cruise departing from a U.S. port, in addition to requiring all staff be vaccinated as well. 

For all ships departing the U.S. and The Bahamas during August, every guest aged 2 and older must also show proof of a negative COVID-19 prior to boarding, regardless of vaccination status. Proof of vaccination for guests departing Florida for the Bahamas will be required starting Sept. 3.

The age of vaccination requirements for different ports of entry vary based on the country of origin.

Anyone looking to go to the Sundance Film Festival in Utah next year is going to need more than a badge. All participants must be fully vaccinated too, festival director Tabitha Jackson said Tuesday.

The 2022 Festival is requiring people attending the festival or Sundance-affiliated events to have received the COVID-19 vaccine. That means everyone from volunteers to filmmakers and passholders. More details will follow in the coming months.

Following the largely virtual Sundance earlier this year, organizers are planning to hold in-person events in 2022 with screenings in Park City and Salt Lake City, Utah, as well as some “satellite” screenings at regional theaters throughout the U.S.

The 2022 Festival is set for Jan. 20-30.

Twitter was, for several months, the leading tech company requiring vaccines for those employees going back into the office. 

The company announced back in May that it would extend its optional work-from-home policy indefinitely, and employees who chose to go back into the office would be required to present proof of a COVID-19 vaccine. 

That requirement was rendered largely moot on Wednesday, when the company said it would be closing its New York and San Francisco offices just two weeks after reopening them, and will pause all planned reopenings for the time being. 

Earlier this week, the Centers for Disease Control and Prevention announced updated guidelines saying even fully vaccinated people should return to wearing masks indoors if they live in areas with high rates of virus transmission. The CDC currently ranks New York as having a substantial rate of community spread, and San Francisco as having high levels of community transmission.

Tyson Foods, one of the largest meat purveyors in the United States, will require all of its 120,000-plus employees to get a COVID-19 vaccine, the company announced Tuesday.

Reports of Tyson's move were first published in the New York Times and the Wall Street Journal.

While negotiations with various unions are ongoing, the company aims to have all office workers vaccinated by Oct.1; all other U.S. employees have until Nov. 1 to get their jabs. The company will offer $200 to frontline workers who can prove they are vaccinated.

“Getting vaccinated against COVID-19 is the single most effective thing we can do to protect our team members, their families and their communities,” Dr. Claudia Coplein, Tyson Foods' Chief Medical Officer, wrote in a statement. “With rapidly rising COVID-19 case counts of contagious, dangerous variants leading to increasing rates of severe illness and hospitalization among the U.S. unvaccinated population, this is the right time to take the next step to ensure a fully vaccinated workforce."

The move makes Tyson the largest domestic food company to mandate COVID-19 vaccinations for its entire workforce, nearly half of whom have already completed their full COVID-19 vaccine regiment.

United Airlines became the first major domestic airline to announce it will require all of its U.S.-based staff to get vaccinated against COVID-19 or face termination from their job. 

“This fall, every U.S.-based United employee will be required to receive a COVID-19 vaccine and upload their vaccination record to Flying Together,” a company-wide statement emailed to employees read in part. 

United initially said that employees had to provide proof of vaccination five weeks after Sept. 20, or five weeks after the Food and Drug Administration (FDA) gives final approval to a COVID-19 vaccine, whichever comes first – putting the last possible date to meet the requirement at Oct. 25. 

But on Aug. 23 when the FDA announced it had granted full approval to Pfizer-BioNTech's COVID-19 vaccine, United moved the deadline up to Sept. 27.

United workers who have already uploaded their vaccine card, or who do so before Sept. 20, will receive an additional day of pay. 

“We know some of you will disagree with this decision to require the vaccine for all United employees,” United CEO Scott Kirby and president Brett Hart wrote to staff. “But, we have no greater responsibility to you and your colleagues than to ensure your safety when you’re at work, and the facts are crystal clear: everyone is safer when everyone is vaccinated.”

The Walt Disney Company said in a statement Friday that it will be requiring all salaried and non-union hourly employees in the U.S. who work on site to be fully vaccinated. 

Employees who aren’t already vaccinated will have 60 days to do so and that those still working from home will need to show proof of vaccination before returning. All new hires will be required to be fully vaccinated before starting work at the company.

“Vaccines are the best tool we all have to help control this global pandemic and protect our employees,” the statement said.

After several weeks of discussions, Walt Disney World and the union groups that represents its performers, hotel workers, bus drivers, merchandise, attractions and food and beverage workers announced on Aug. 23 they had reached agreements on mandatory COVID-19 vaccinations for workers under those unions.

Walt Disney World indicated that it has come to agreements with the Service Trades Council Union and Actors Equity Association. Disney World officials said they are continuing negotiations with the other unions.

Walmart is requiring that all workers at its headquarters as well as its managers who travel within the U.S. be vaccinated against COVID-19 by Oct. 4.

The retailer based in Bentonville, Arkansas, is also reversing its mask policy for its employees working in stores, clubs, distribution facilities and warehouses. Going forward, they will be required to wear masks in areas with high infection rates, even if they have been vaccinated.

The moves are part of a series of sweeping measures the nation’s largest retailer and private employer announced last Friday to help curb the spread of the virus and drive more of its workers to get the shot in the arm.

The vaccine mandate excludes frontline workers, who the company says have a lower vaccination rate than management. But it’s hoping that managerial employees, who represent just a fraction of its 1.5 million workers, will serve as inspiration.

“We’re hoping that will influence even more of our frontline associates to become vaccinated,” Walmart spokesman Scott Pope said.

NOTE: This is a developing story and will be updated with future announcements. 

The Associated Press contributed to this report. Spectrum News' Haeli Spears and Christie Zizo also contributed to this report.