The Centers for Disease Control and Prevention (CDC) said Canadians who receive the Oxford-AstraZeneca vaccine could enter the US when they announce new travel restrictions in November. However, it's not clear whether those with mixed doses will be eligible to travel south of the US-Canada border.

The CDC announced Monday that travelers vaccinated with the World Health Organization (WHO) and the US Food and Drug Administration (FDA) approved vaccines for emergency use meet the US travel requirements, reported the National Post.

In correspondence with CDC spokesperson Jasmine Reed, they intend to release "additional guidance and information as the travel requirements are finalized," she writes. Reed said the CDC began informing airlines of its decision last week, but did not respond to a request for comment by The Canadian Press at the time of writing.

Last month, White House officials said fully vaccinated international travelers could begin travelling to the US in November but were unclear on what vaccines they approved. The FDA approved three COVID vaccines, though the list did not include AstraZeneca among them. However, the WHO approved the vaccine. The FDA also clarified it did not permit mixing doses of Pfizer and Moderna.

Over 3.9 million Canadians not from Quebec received mixed doses of Health Canada approved vaccines. According to the Public Health Agency of Canada data, about 1.6 million had a dose of  AstraZeneca and then an mRNA vaccine. It's not clear that those who received this mixed-dose combination hold eligibility for travel to the US.

Per WHO's emergency use listing, they only assessed those who received the same vaccine for both shots. But the agency's Strategic Advisory Group of Experts on Immunization recommended mRNA vaccines — Pfizer-BioNTech or Moderna — can be used for the second dose following a first dose with the AstraZeneca vaccine if a second dose of AstraZeneca is unavailable.

The National Airlines Council of Canada is backing the CDC's decision. "As countries move forward and recognize WHO-approved vaccines, it underscores the critical need for the Canadian government to do likewise and accept the global standard established by the WHO," wrote Mike McNaney, the group's president and chief executive officer, in an emailed statement. The CDC decision means US officials will recognize all six.

Ottawa recognized Moderna and Pfizer-BioNTech mRNA vaccines and the AstraZeneca and Johnson & Johnson vaccines, but not the WHO-approved Sinopharm or Sinovac shots. Travellers to Canada must receive two doses of Health Canada-approved vaccines at least two weeks before entering the country to be considered fully vaccinated. "The list of accepted vaccines may expand in the future as evidence becomes available," wrote a Health Canada spokesperson in a statement Monday.

A spokesperson with Global Affairs Canada said Ottawa "respects the right of the United States to determine its border restrictions." Genevieve Tremblay writes, "The government of Canada is working with partners, including the United States, advocating for the recognition of Canada's successful, science-based vaccination strategy abroad, which includes mixed vaccination schedules, extended dose intervals and a portfolio of safe and effective vaccines." Passengers must also show proof of vaccination before boarding, and a negative COVID test took no more than three days before departure.