Southwest Airlines, American Airlines, and Delta Air Lines announced that they will not be requiring their employees to get vaccinated against the COVID-19. The heads of the three airlines said they are still encouraging unvaccinated workers to get their shots, but it will not be a strict requirement.

The announcement breaks away from the mandate imposed by other U.S. airlines, which have planned to make employee vaccinations a requirement. Southwest Airlines CEO Gary Kelly said the spread of the Delta variant is concerning, but they have decided to stick with their current company policy.

Delta Air Lines CEO Ed Bastian echoed the same sentiments and added that more than 75% of their workers are inoculated. He said workers are now choosing to get vaccinated by their own accords even without a company mandate.

The high rate of vaccinated workers at Delta  Air Lines can be attributed to a vaccinate mandate imposed on all new hires back in May. After it was imposed, the company rejected applications from unvaccinated applicants.

American Airlines CEO Doug Parker said the company is providing incentives for people to get vaccinated even if it is not making it mandatory. The company plans to give workers an extra day of vacation next year if they get vaccinated before the end of this month.

"We certainly encourage it everywhere we can encourage it for our customers and our employees, but we're not putting mandates in place," Parker said.

Last week, United Airlines became the nation's first major airline to impose a vaccination mandate. United informed all of its workers that anyone not vaccinated by Oct. 25 would get fired. The mandate applied to the company's 67,000 workers in the U.S., who all have to present proof of vaccination before the deadline.

Just a few days later, Frontier Airlines also made a similar announcement. The company told employees that if they are not vaccinated before October, they may face regular testing and certain work restrictions.

Earlier in the week, Hawaiian Airlines became the third major carrier to issue a vaccination mandate to its employees. The company's CEO, Peter Ingram, told employees via a staff memo Monday that they all have to be fully vaccinated by the end of October.