United Airlines CEO Scott Kirby painted a stark picture of how quickly he says the company's vaccine mandate has kept United employees out of the hospital. Kirby made the remarks in a letter to staff posted to the company's website on Tuesday.

In the letter, Kirby wrote that while United Airlines has around 3,000 employees who are "currently positive for COVID," the company has reported zero COVID-related deaths in the past "eight straight weeks." Kirby said in the letter that over one United employee "on average *per week* was dying from COVID," before the company's vaccine mandate was imposed.

Kirby emphasized that according to company data, this means that around 8-10 United employees are alive today because of the company's vaccine requirement.

As Fortune reported, over half of United Airline's 67,000 U.S.-based employees were vaccinated by September. The rest at that time were waiting on their first dose or had chosen to face unpaid leave or termination.

Kirby told CBS Mornings in October of last year that 232 United employees were subsequently fired.

The Chicago-based company reportedly has one of the strictest company vaccine policies in the United States, and as NBC Chicago reported in November, at least six employees had filed a suit to block the policy in September. A federal judge in Texas ruled to allow United to continue with its policy.