The U.S. Centres for Disease Control and Prevention said Monday travellers will be able to fly to the States if they’ve received shots of vaccines approved or recognized for emergency use by the World Health Organization or the U.S. Food and Drug Administration. It did not say whether that included people who had received a mixed-dose regimen of approved vaccines.

“CDC will release additional guidance and information as the travel requirements are finalized,” said a statement from spokeswoman Jasmine Reed. The agency began informing airlines of its decision last week, she added.

Last month, White House officials said international travellers would be allowed to visit beginning in November as long as they were fully vaccinated. They did not say which vaccines would meet that criteria.

The U.S. Food and Drug Administration has approved three COVID-19 vaccines, and AstraZeneca was not among them. It is, however, approved by the WHO. It also does not allow for mixing doses of Pfizer and Moderna.

The COVID-19 vaccines approved under the WHO’s emergency use listing have only been assessed as single product regimens, meaning people receive the same vaccine for both shots.