American Airlines is telling its pilots to take the COVID-19 vaccine on their days off if they choose to be inoculated against the virus, which the company is not currently requiring, according to a memo reviewed by Reuters.

"Your decision to take the vaccines is a personal decision and is currently not required by the Company," American's managing director of line operations, Chip Long, and managing director of flight operations, John Dudley, said in the joint memo.

"As such, if you elect to take the vaccine you should schedule it on your days off and so that it does not impact your ability to be in place and operate your scheduled flying given the 48-hour requirement," they said.

The Federal Aviation Administration has said pilots and controllers must not fly or conduct safety-related duties for 48 hours after receiving a COVID-19 vaccine.

Asked about the memo, American Airlines said it is working on plans to provide the vaccine to pilots and other employees as it becomes available in different states but does not plan to require them unless they are mandated by certain countries for entry.

"As we work to develop a program to connect our team with the COVID-19 vaccine, we are encouraging team members to get vaccinated as opportunities arise for them to do so," spokeswoman Stacy Day said.

Inoculation against the disease caused by the coronavirus is considered key to safely reopening large parts of the US economy.

Air travel has been particularly hit hard by the pandemic, and strict rules putting health-care workers first in line has slowed the rollout in the United States. States are now being urged to vaccinate anyone over 65 as well.