With much of the world under some form of lockdown to slow the spread of COVID-19, and debates rage over when, and how, to reopen the global economy in order to avoid the next great depression, the light at the end of the tunnel has been top-down predictions of a vaccine within 18 months.
JPMorgan, for example, makes a core assumption that "it could take 12-16 months for a vaccine to be under mass production," and that the US will go through cycles of increased distancing measures followed by virus flare-ups, which require more lockdowns.
Yet after bold predictions and vaccines rumored to be 'just around the corner,' Dr. Anthony Fauci, director of the US National Institute of Allergy and Infectious Disease who sits on President Trump's coronavirus task force, offered a less enthusiastic view - saying in early March that a vaccine might be available in 12 - 18 months.
"The whole process is going to take a year, a year and a half, at least," said Fauci.
Fauci has to tamp down on vaccine expectations which causes the President to ask him to talk about therapeutics pic.twitter.com/gUrOVs0l8H— Acyn Torabi (@Acyn) March 3, 2020
And while Fauci has been accused of fear mongering - relying on wildly-pessimistic models while advising President Trump on lockdown measures, he may have been wise to downplay the vaccine timeline.
According to a new report by Australia's ABC, the creation of a vaccine may be incredibly difficult for several reasons, as this particular coronavirus is 'posing challenges that scientists haven't dealt with before.'
According to Ian Frazer of the University of Queensland - who was involved in the creation of the HPV vaccine, coronaviruses are particularly difficult to create safe vaccines before because the virus infects the upper respiratory tract, which our immune system isn't particularly adept at protecting.
There are several reasons why our upper respiratory tract is a hard area to target a vaccine.
"It's a separate immune system, if you like, which isn't easily accessible by vaccine technology," Professor Frazer told the Health Report.
Despite your upper respiratory tract feeling very much like it's inside your body, it's effectively considered an external surface for the purposes of immunisation.
"It's a bit like trying to get a vaccine to kill a virus on the surface of your skin." -ABC News
In other words, because the upper respiratory tract is effectively "outside" of the body, and the outer layer of (epithelial) cells in the tract is our natural barrier to viruses, it's difficult to produce an immune response which can reach them.
Complicating matters is that if a vaccine causes an immune response that doesn't benefit the target cells, the result could potentially be worse than no vaccine at all.
"One of the problems with corona vaccines in the past has been that when the immune response does cross over to where the virus-infected cells are it actually increases the pathology rather than reducing it," said Frazer. "So that immunisation with SARS corona vaccine caused, in animals, inflammation in the lungs which wouldn't otherwise have been there if the vaccine hadn't been given."
Antibodies, meanwhile, don't last forever
The human immune system releases antibodies to neutralize threats such as viruses. With the coronavirus, those who have been infected have shown varying degrees of antibody production - with some weak and some strong. That said, antibodies don't last forever.
"Yes, you get antibodies after a [cold] infection, and yes it lasts for a while, but it's not lifelong... sort of months rather than years," said Frazer. "I think it would be fair to say that the natural immunity that you get after infection from this coronavirus is probably going to turn out like the coronaviruses we've seen in the past."
That said, "The good news is that if you get reinfected with the virus a second time some months down the track, there will probably be enough immunity there to stop you becoming seriously ill."
Vaccines under development
Current efforts to find a cure have ranged from the use of deactivated virus fragments like we do with influenza, to using mRNA to induce an antibody response. Many will fail before a successful treatment is found, according to the report.
Professor Frazer's prediction is that the most likely candidate will be a vaccine that uses a part of the virus attached to a chemical to induce an immune response, or "subunit" vaccine.
"That [vaccine type] has been successful in animal models for coronaviruses in the past and that is of course where the money is being put in large measure at the moment," he said.
"Another sort of vaccine would be just antibody transferred from somebody who had been infected already and had got rid of the infection.
"Which would be an immunological means of preventing infection, and could probably be more quickly developed than an actual vaccine."
This sort of vaccine was tested with SARS in 2003 and resulted in reinfected lab monkeys having a nasty immune response, which is why many groups working on a vaccine for Sars-CoV-2 are going for a very specific antibody response.
Professor Frazer said the narrow, targeted approach is fine, unless you pick the wrong specific antigen — the substance that stimulates an immune response which antibodies bind to — in which case you could end up with the same problem. -ABC News
Perhaps the best minds in the world focusing all of their efforts on COVID-19 will be able to crack the code and develop a successful vaccine. Then again, we also don't have vaccines against HIV and cancer despite decades of efforts.
"I think it would be fair to say even if we get something which looked quite encouraging in animals, the safety trials in humans will have to be fairly extensive before we would think about vaccinating a group of people who have not yet been exposed to the virus," according to Frazer.
"They might hope to get protection but certainly wouldn't be keen to accept a possibility of really serious side effects if they actually caught the virus."