For much of the COVID-19 pandemic, Australia and New Zealand have been the envy of the world when it came to keeping the virus at bay. But with the rise of the super-contagious Omicron variant, the lands down under have seen a recent resurgence of cases – and now hospitals, testing facilities, and antipodean tempers have all been feeling the strain.

That’s why it caused such an uproar when news broke Tuesday that Novak Djokovic, the current world number one tennis player seeking to defend his title at this month’s Australian Open, had been granted a medical exemption from the mandatory double vaccination required to enter the country.

“People with loved ones who are dying/some needing urgent treatment cannot get into their own states,” tweeted former Australian Rules football player Corey McKernan. “You tell people they can't go to Coles [a supermarket] or a cafe without being vaxxed but if you're world number one you get a pass? Fucking disgrace.”

Immediately, Australian authorities appeared to reverse course. Upon arriving in Melbourne airport, Djokovic was held by border authorities who announced that he had not met conditions for entry, and so his visa would be canceled. The tennis star was taken to a notoriously grim detention hotel, where he now awaits a decision on his deportation.

But how did it come to this? And where else might the famously anti-vax athlete find himself barred from competing in the post-COVID-19 world?

What are COVID Vaccine medical exemptions? 

Well, depending on how you look at it, the Djokovic debacle is either very simple, or really quite complicated indeed. Basically, according to current Australian law, all travelers to the nation must either be double vaccinated or else have a valid medical exemption. Djokovic is not vaccinated, and therefore unless he has a medical exemption – and the Australian border force has determined that he doesn’t – he can’t enter the country. As fellow world champion tennis star Rafael Nadal put it, “there are rules, and if you don’t want to get the vaccine, then you can have some troubles … if he wanted, he would be playing here in Australia without a problem.”

So did Djokovic think he could skirt the rules? Of course, some cynics – and some pro athletes – have suggested the tennis champ was relying on his reputation to get past the regulations, but there’s more at play here. To get that medical exemption, Djokovic would have had to be approved by two separate independent medical panels – a process which, top tennis coach Paul Annacone told Reuters, is anonymous. For Djokovic, those medical panels were organized by Tennis Australia, the body that runs the Australian Open, and the state of Victoria, where the event is held – and both cleared him for a medical exemption. Why?

Normally, an exemption would be given for a specific medical condition such as an inflammatory cardiac illness – something that genuinely precludes a person from safely receiving the vaccine. You can also be exempt if you are receiving end of life care, have ASD or a mental disorder where vaccination will cause distress, if you're pregnant (though it is safe and advised you do), about to have surgery, or had a serious reaction to a first dose.

But when the Victorian state government announced its medical exemption criteria back in December, they included another option: “Evidence of medical exemption for overseas travelers,” the state website says, could take the form of “a documented diagnosed COVID-19 infection confirmed by a PCR test within the previous 6 months.”

That’s right: like Florida before them, Victoria had added in a provision for so-called “natural immunity” from previous infection – albeit only a temporary one. Those rules were adopted by Tennis Australia as well, and so, since Djokovic apparently said he had recovered from a COVID-19 infection in the past six months, he passed both panels. There was just one hitch in the plan: the Australian Border Force is a federal agency, and their criteria for medical exemptions were a little more stringent.

“Federal government sources confirmed that discussions were held between the Victorian government, Tennis Australia and Border Force about the valid exemptions for not being vaccinated,” writes Anthony Galloway for The Age. “According to one source, Tennis Australia was told explicitly in writing a number of times that a recent COVID infection was not an acceptable reason not to be fully vaccinated.”

So, vocally anti-science though Djokovic may be – and let’s face it, the guy does appear to think you can purify water through sheer force of will – his current status in Australian immigration limbo may actually be the result of an honest mistake.

What are COVID vaccination entry laws for other countries?

While his team is mounting a legal challenge to his visa revocation, it’s yet to be seen whether the tennis star will be able to win yet another Grand Slam this year. Should Djokovic be successful in entering Australia, he would next need to gain entry to France to compete in the French Open in late May. Assuming he remains unvaccinated, that will mean another round of COVID-19 for the apparently sniffly champ: for Serbian citizens like Djokovic, a “certificate of recovery between 11 days and 6 months old may … serve as a COVID certificate,” per the French Foreign Office.

Wimbledon in the UK would be next, and luckily for Djokovic the terms of entry for the unvaccinated are much looser in England: he would merely need to quarantine in place for 10 days and take three COVID-19 tests, all of which come up negative, before the tournament.

But the final contest in the Grand Slam set – the US Open – may be the hardest of all for Djokovic to play. While certain states have been notoriously lax with vaccination regulations, the federal US government has taken a much stricter tack. TSA agents have been tasked with ensuring all visitors to the USA can prove they are either fully vaccinated or have a medical exemption – and the CDC makes it clear that these are reserved for those “for whom receiving an accepted COVID-19 vaccine is medically contraindicated as determined by a licensed physician.”

“COVID-19 vaccinations have been overwhelmingly proven to be safe and effective at preventing severe illness, hospitalizations, and deaths from COVID-19,” the agency guidance notes. “[The] CDC intends for this exception to be applied in strict accordance with scientific evidence.”

And Novak’s reason – that he is “personally … opposed to vaccination and [he] wouldn’t want to be forced by someone to take a vaccine in order to be able to travel,” as he said back in 2020 – probably isn’t going to cut it, scientifically speaking. So, unless the rules change in the next nine months or so, the tennis number one has a choice to make: either vaccine up, or resign to merely being another example of ironic nominative determinism.