More than 100 different vaccines are currently under development globally — the biggest and most impressive vaccine development campaign in history by far. However, “there’s no guarantee that the vaccine is going to be effective,” White House health advisor Dr. Anthony Fauci told Congress.

Dr. Fauci’s remark was made when he testified earlier today in front of the Senate Committee on Health, Education, Labor and Pensions about how the economy might reopen in the United States.

“You can have everything you think that’s in place and you don’t induce the kind of immune response that turns out to be protective and durably protective,” Fauci said of a vaccine. “So one of the big unknowns is, will it be effective? Given the way the body responds to viruses of this type, I’m cautiously optimistic that we will with one of the candidates get an efficacy signal.”

Although he did not mention this during the Congress hearing, there is no vaccine for any coronavirus despite we’ve known about some members of this virus family for decades.

Professor Ian Frazer, a world-renowned Australian immunologist, said that coronaviruses have historically been hard to make safe vaccines for, partly because the virus infects the upper respiratory tract, which our immune system isn’t great at protecting.

On Monday, the World Health Organization (WHO) chief there are around seven or eight “top” candidates for a vaccine against the coronavirus.

Their development has been accelerated in order to bring the crisis to a close as fast as possible. With this in mind, leaders from 40 countries, organizations, and leading banks have pledged $8 billion last week.

Even so, it might take at least 12-18 months before this happens. The fastest vaccine that has ever been developed is four years, the mumps vaccine made in the 1950s.

Furthermore, after at least three clinical trials deeming the vaccine safe, you’d still have to manufacture billions of doses and fairly distribute them across the world.

“We have good candidates now,” said WHO Director-General Tedros Adhanom Ghebreyesus during a U.N. Economic and Social Council video briefing. “The top ones are around seven, eight. But we have more than a hundred candidates.”

“We are focusing on the few candidates we have which can bring probably better results and accelerating those candidates with better potential,” he said.

The risk of backfiring

Vaccines cannot and should not be hurried. However, this is an extraordinary situation that explains the acceleration or vaccine development across the world.

During the same testimony to Congress, Dr. Fauci also expressed his worries that a vaccine that isn’t fully vetter might end up doing more harm than good, strengthening the virus instead of weakening it.

He went on to give examples of two vaccines that have produced a suboptimal response in the past.

“And when the person gets exposed, they actually have an enhanced pathogenesis of the disease, which is always worrisome. So we want to make sure that that doesn’t happen. Those are the two major unknowns.”

Even Fauci remains “cautiously optimistic that we will have a candidate that will have some degree of efficacy, hopefully, a percentage enough that will induce the kind of herd immunity that would give protection to the population at home.” “