Many Canadians hoping to visit the U.S. have been nervously eyeing incoming American travel regulations. Starting in November, the Biden administration will require that anyone flying into the U.S be fully vaccinated. Those who don’t comply will be refused entry.

At first glance, the move, which is aimed at curbing the spread of COVID-19 locally, shouldn’t irk Canadians. We have a higher vaccination rate than Americans, and the Canadian government is also set to bring in rules requiring air travellers here to be vaccinated. However, the U.S. has yet to approve the mixing of COVID-19 vaccines, meaning large numbers of Canadians who had two different shots might not be considered vaccinated south of the border.

The Centers for Disease Control and Prevention (CDC) – the U.S. premier public health agency – says that coronavirus vaccines are, “not interchangeable.” According to the agency, “if you received a Pfizer-BioNTech or Moderna COVID-19 vaccine, you should get the same product for your second shot.” Not doing so purportedly risks being considered – in the eyes of U.S. regulators at least – not fully vaccinated.

In Canada, millions were given the green light to combine shots. The National Advisory Committee on Immunization – which advises the Canadian government – noted that vaccines can be “considered interchangeable and should be offered to complete the vaccine series.” Over 3.8 million Canadians opted to mix and match vaccines – for good measure, even the Prime Minister got in on the action.

Should these Canadians worry about heading south of the border? I doubt it. Here’s why.

Current U.S. vaccine policy favours – rather than mandates – double jabs from the same manufacturer. Indeed, a close look at the CDC’s own website shows that individuals receiving two doses from different vaccine manufacturers can in fact be considered fully vaccinated. There are caveats, the most notably being your doses must be mRNA vaccine products (Pfizer-BioNTech’s Comirnaty and Moderna’s Spikevax). But mixing mRNA and non-mRNA vaccines (for example, AstraZeneca’s Vaxzevria) isn’t clearly prohibited. The CDC says, ”every effort should be made to determine which vaccine product was received as the first dose to ensure completion of the vaccine series with the same product.” Assuming you expend this effort and still come up short, nothing explicitly bars you from claiming the title of being fully vaccinated.

This gives the U.S government wiggle room. That’s something they are likely going to need. The reason? Canada isn’t the only country to adopt a mix-and-match approach. Countries like France, Germany and Italy have taken a similar approach to vaccinating their populations. So have Finland, Indonesia and Thailand. Penalizing U.S.-bound visitors from these countries owing to domestic inoculation efforts risks drawing public ire on two fronts.

The first is political. A mix-and-match approach to vaccination was adopted by many countries in part because there wasn’t enough of one vaccine type to go around. The reason? The U.S. was busy hoarding global supply. President Joe Biden wanted to see every American vaccinated, which prompted him to refuse shipping vaccines abroad. But vaccine-hesitant Americans felt differently, which has culminated in over 15 million vaccines being thrown away owing to disuse. Given this reality, the U.S. is poorly poised to fault other countries for their approach to vaccination.

More importantly, a hardline approach to jabs risks drawing the ire of U.S. businesses, most notably, the airline industry. When it comes to the pandemic, few industries have lost as much cash (and laid off as many workers) as U.S. carriers. At the height of the pandemic, American Airlines was burning through $89 million per day; hardly chump change. The carrier – and its counterparts – need to stem those loses and getting people to fly is a surefire way to do that (incidentally pressure from the airline industry may also explain why Canadians could easily fly into the US during the pandemic but not follow suit by land).

So if not for any other reason other than financial interests alone, expect the U.S. to slowly but surely embrace mixed-dose jabs. Even during a pandemic, cash is king.

Image credit: muratart