United Airlines says that more than half its employees who weren't vaccinated last month have gotten their shots since the company announced that vaccines would be required.

The airline's 67,000 U.S.-based employees face a Sept. 27 deadline for getting vaccinated. United said Wednesday, however, that employees whose bids for exemptions based on medical reasons or religious beliefs are denied will get five more weeks to get vaccinated.

After that, the airline said, they will face termination or unpaid leave.

Kirk Limacher, United's vice president of human resources, made the statement about vaccinations Wednesday in memos to employees that spell out how United will handle requests for exemptions.

United declined to say exactly how many employees have recently been vaccinated, what percentage of the workforce is now vaccinated, or how many workers requested an exemption. The airline said it will have enough workers to operate its schedule this fall and into the holidays.

The airline said that in most cases, employees who refuse to get vaccinated won't be allowed into the workplace starting Oct. 2.

United says requests for medical exemptions will be judged by medical staffers including nurses, while requests for waivers based on religious beliefs will be handled by personnel-office employees.

The process for handling workers whose exemptions are approved will vary slightly depending on the employee's job.

Workers who routinely come in contact with passengers, such as flight attendants, gate agents and pilots, and whose exemptions are approved will face indefinite unpaid leave starting Oct. 2. They won't be allowed back on the job until the pandemic "meaningfully recedes," according to one of the memos.

Employees who rarely deal with passengers — examples include baggage handlers and mechanics — and whose exemptions are approved will also be put on leave, but only until the airline comes up with a plan for weekly testing and mandatory mask-wearing for them.

Headquarters employees whose exemptions are approved will be placed on leave until United decides on safety measures, including whether the person needs to come into the office.

In explaining the rules to employees, United cites statistics on the state of the pandemic in the U.S., where new infections are at their highest level since March and "likely to rise into the fall as more people are hospitalized." Most of the cases, hospitalizations and deaths are occurring among unvaccinated people, the memos said.

Chicago-based United has taken the strongest pro-vaccination stance among U.S. airlines. Delta Air Lines says it will levy a $200 monthly surcharge on unvaccinated employees who are covered by the company's health plan. Others including American Airlines say they will cut off paid leave for unvaccinated workers who contract COVID-19.