(On Wednesday, 29 September, AstraZeneca's US clinical trial results were published wherein the vaccine was found to have an overall efficacy of 74 percent, and an estimated 64.3 percent efficacy in preventing infection.)

With talks of COVID-19 turning endemic, and the world slowly reverting to its pre-pandemic self, the focus is now on assimilating into the post-pandemic world – a world to which access is restricted by green passes, and vaccine certificates.

The question then becomes, 'who gets to be on the guest list?'

For instance, if you were one of Bruce Springsteen's fans waiting to watch him perform live in New York in June, and you were fully vaxxed (as per the entry rules)...but with the AstraZeneca vaccine, you would have been in for a disappointment, as you would have been banned from the show as only those who had taken the FDA approved COVID-19 vaccines were permitted to attend.

Although last month New York agreed to recognise AstraZeneca, this entry restriction still applies to many events in many parts of the US, and has had more drastic implications than being locked out of concerts.

The US was one of the first countries to strike a deal with AstraZeneca when their COVID vaccine was first announced in mid 2020.

But more than a year down the line, the vaccine has still not been granted approval in the country.

This when the vaccine has been approved by the WHO, the EMA, and has been rolled out in over 176 countries.

The US has, from the get go, questioned AstraZeneca's safety and efficacy pointing to a lack of sufficient reliable data from a large enough human trial.

For this reason, the company decided to conduct Phase 3 trials for the vaccine in the US itself, on around 37,000 participants – a study funded by the US Government.

But this was only the beginning of a long drawn out ordeal of miscommunications and trust issues between AstraZeneca and the US health authorities.

To understand the complex back and forth, here's a quick run down of the timeline of events.

On 21 May, 2020 the US Government signed a deal with AstraZeneca for 300 million doses of their COVID vaccine. The deal also involved support cost of 1.2 billion USDs for clinical trials as well as setting up facilities for it's production.

On 1 September, AstraZeneca began its phase 3 clinical trials in the US.

In September, the company also faced it's first roadblock. Human clinical trials for the vaccine were halted across the world when a participant in the UK developed serious neurological issues.

The problem was soon resolved and trials resumed. The clinical trials in the US, however, remained on pause until October.

On 23 November 2020, AstraZeneca and the University of Oxford announced the initial results of the Phase III clinical trials in the U.K., Brazil, and South Africa. The study found the vaccine safe and effective.

On 30 December, the Oxford-AstraZeneca Vaccine received emergency use approval in the UK.

On 22 March, AstraZeneca released results of the US clinical trials, claiming 79 percent efficacy against symptomatic infection.

On 25 March, AstraZeneca then put out a statement clarifying that the data published by them were interim results from February, according to Nature.

They then released revised results with a drop in the vaccine's efficacy to 76 percent.

Which brings us to July. AstraZeneca submited its data for, not an EUA, but a full regulatory approval from the FDA in the US. The process for which could take months to go through, if at all.

On 29 September, the company published the results of its phase 3 clinical trials in the US which showed the vaccine has an overall efficacy of 74 percent, in the general population and an estimated 83.5 percent in those over the age of 65.

The situation was different back in May of 2020, when the US first signed a deal with AstraZeneca. Back then the world was in the midst of a full blown pandemic with no end in sight, and governments were desperate to call dibs on as many doses of the first vaccine they could get hold of.

But now that we are no longer in the emergency situation we were in back then, authorities are perhaps inclined to be more careful while weighing the risks and benefits of vaccines for approval.

Perhaps the issue is that of procurement? After all, all the three vaccines that are in use in the US currently–Johnson & Johnson, Pfizer and Moderna– have been produced in the country. Importing vaccines at a higher cost could seem unnecessary.

It turns out, the AstraZeneca vaccines are also being produced in the US, just not for domestic use. These vaccines are mostly being exported as part of the COVAX initiative to provide vaccine coverage in lower and middle income countries

Ultimately, the delaying could have to do with US authorities wondering if the country even needs a fourth vaccine when the three approved homegrown vaccines are able to cover the required supply and even provide surplus for booster doses.

An FDA approval, however, implies more than just which vaccines the US citizens are allowed to take.

As borders open up, the deepest impact of this exclusion will be felt on international travels–particularly of tourists, trade and international students.

According to the world population review, the US was the third most popular place for travel in the world in 2019.

Just last month, the WTTC (World Travel and Tourism Council) urged the US to 'urgently speed up' approval of the AstraZeneca vaccine for the sake of resurrecting transatlantic travels.

“This will leave airlines, cruise lines, tour operators, hotels and the entire travel and tourism infrastructure, which depends upon transatlantic travel, in significant trouble for the foreseeable future," said Virginia Messina, Senior Vice President of WTTC said in a statement.

Referring to a 'vaccine vacuum' she adds, “every day which passes, and transatlantic travel remains off limits, it leaves the Travel & Tourism sector sinking deeper into the red.”

Moreover, to not be recognised by the US health authorities like the CDC and FDA could prove to be a black spot on the vaccine's reputation and the trust it garners from consumers elsewhere in the world.

When restrictions based on FDA approvals are placed on access to indoor events and public spaces, it could also translate into vaccine inequality and even vaccine shaming.

It could also discourage people in countries where both AstraZeneca and other US vaccines are offered, from choosing the former to simply avoid any future hassle.