For a while there, it almost looked like we could have had a coronavirus vaccine in just months.
Trials of several candidates, including the much-vaunted Oxford vaccine, which Australia has backed, were showing promising results.
US President Donald Trump was so confident that on Monday he said "we'll have the vaccine soon, maybe before a special date". That "special date" almost certainly refers to the November 3 polling day.
And then came today's sobering reality check that trials of the Oxford Covid-19 vaccine, which the Australian government has pre-ordered 30 million doses of, has been halted following an "unexplained illness" in one of the people given the shot.
Virus experts have said the brutal truth of vaccines is they often take years to develop. With all the will in the world, there's only so many months you can shave off that timeline. Any hope that we might be celebrating the end of Covid over Christmas lunch is likely to be dashed.
"For the general public, a vaccine would probably be later in 2021," an immunologist has told news.com.au.
UK-Swedish pharmaceutical giant AstraZeneca has said phase III trials of the Oxford vaccine were being paused following what is referred to in the pharmaceutical industry as an "adverse event".
"This is a routine action that has to happen when there is potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials," the company said in a statement.
AstraZeneca insisted the illness was a "single event" but did not give any details as to what the patient came down with.
Mild side effects, such as fever, headaches and localised pain, had already been noted and were considered mild or moderate. As such, it's likely the adverse event was more serious. Although the patient is set to recover.
The firm and Oxford University will likely spend several weeks trying to gauge if the person randomly came down with something, or if it's linked to the vaccine. They will also be watching carefully to see if anyone else on the trial suffers the same malady.
All this takes time. And it illustrates the tension between just how impatient the world is to get back to normal and the many years it can take to develop a safe and effective vaccine.
Speaking to the ABC's 7.30 on Tuesday night, University of Queensland immunologist Professor Paul Young said the expectation on how quickly a vaccine could be rolled out was unrealistic.
"The likelihood of any vaccine being deployed before Christmas is unlikely. It's dangerous to push too hard.
"The timelines we have been working with are nothing like we have ever experienced before," he said.
"I know that there is urgency and there is a desire to get something out there more quickly than perhaps it could do, but we are accelerating this as fast as possible."
Last week, the World Health Organisation also warned against betting on an early jab for the virus.
"We are not expecting to see widespread vaccination until the middle of next year," the WHO's Margaret Harris said in Geneva.
"Phase III must take longer because we need to see how truly protective the vaccine is and we also need to see how safe it is."
Right now, a whole heap of vaccines are making their way down the approval pipeline.
Most are at the preclinical stage, where they are being tested on animals to see if an immune response is triggered.
A potential vaccine from the University of Queensland, which the Australian Government has also bet big on pre-ordering 51 million doses, is at this stage.
Just a handful have progressed to human trials: the Oxford/AstraZeneca vaccine, a US- German candidate which has the backing of pharma giant Pfizer and two Chinese potentials.
Human trials begin at phase I, when a small cohort are given a dose, and proceed to phase III, when the drug has proved to be safe enough up for thousands to take a dose.
Phase III is also where the process slows because so many people are involved. Getting from approval to production can take usually between two and 10 years to be approved.
"The development of a Covid-19 vaccine has been surprisingly smooth," immunologist and RMIT research fellow Dr Kylie Quinn told news.com.au.
"But phase III is where they can fall down. This is where things can go wrong and that's where we have to see in the real world if the vaccine can protect people but also if there are any rare side effects."
The Oxford trial involved 30,000 people. Half the cohort were given the real jab with the rest getting a placebo. Around 17,000 people had commenced on the trial when it was halted.
"One event in 17,000 people is rare but they are doing there due diligence," said Dr Quinn.
Trump is betting on what's he's calling "Operation Warp Speed", a $14 billion push behind two vaccines including Pfizer's to find a vaccine and start cranking it out at, as the name suggests, at warp speed.
At a rally last week, the President was bullish, telling the crowd: "It will be delivered before the end of the year, in my opinion, but it really might even be delivered before the end of October".
Not even Operation Warp Speed's own staff seem that gung-ho.
Talking to the US' National Public Radio last week, chief adviser for the programme Moncef Slaoui said a vaccine by the end of next month was "a possibility, but very unlikely".
But he "firmly believed" high risk groups, those over 70 and frontline healthcare workers, in the US could begin to be vaccinated by the end of December.
Dr Quinn said the approval process was going as fast as "humanly possible".
"I've been really impressed about how rapidly things are moving forward and lot of that has been by reducing bureaucratic and logistical hurdles but ensuring we still get the same safety and immunity data.
"But there are some things we can't compromise on," she said.
"Early batches of a vaccine could be available next year for high risk groups and that's sensible to prioritise; but for the general public a vaccine would probably be later in 2021."
It's a vaccine reality check and a stark reminder you can only rush the process so much.
However, there was good news too, said Dr Quinn.
Firstly, this could just be a bump in the road for the Oxford vaccine. The adverse event may not be connected to the drug or it may mean the vaccine is not prescribed to certain groups.
But even if it doesn't pass muster, all is not lost.