Pfizer Inc. took a pandemic-stricken world by storm this week by disclosing that its COVID-19 vaccine may be a remarkable 90% effective, based on early and incomplete test results that nevertheless brought a big burst of optimism to a world desperate for the means to finally bring the catastrophic outbreak under control.

The announcement came less than a week after an election seen as a referendum on President Donald Trump's handling of the scourge, which has killed more than 1.2 million people worldwide, including almost a quarter-million in the United States alone.

"We're in a position potentially to be able to offer some hope," Dr. Bill Gruber, Pfizer's senior vice president of clinical development, told The Associated Press. "We're very encouraged."

Pfizer, which is developing the vaccine with its German partner BioNTech, now is on track to apply later this month for emergency-use approval from the U.S. Food and Drug Administration, once it has the necessary safety information in hand.

Even if all goes well, authorities have stressed it is unlikely any vaccine will arrive much before the end of the year, and the limited initial supplies will be rationed.

Dr. Anthony Fauci, the U.S. government's top infectious-disease expert, said the results suggesting 90% effectiveness are "just extraordinary," adding: "Not very many people expected it would be as high as that."

"It's going to have a major impact on everything we do with respect to COVID," Fauci said as Pfizer appeared to take the lead in the all-out global race by pharmaceutical companies and various countries to develop a well-tested vaccine against the virus.

Dr. Bruce Aylward, the World Health Organization's senior adviser, said Pfizer's vaccine could "fundamentally change the direction of this crisis" by March, when the U.N. agency hopes to start vaccinating high-risk groups.

Global markets, already buoyed by the victory of President-elect Joe Biden, rallied on the news from Pfizer. The S and P 500 finished the day with a gain of 1.2%, while the Dow Jones Industrial Average rose more than 800 points. Pfizer stock was up more than 8%.

Still, the announcement doesn't mean for certain that a vaccine is imminent: This interim analysis, from an independent data monitoring board, looked at 94 infections recorded so far in a study that has enrolled nearly 44,000 people in the U.S. and five other countries.

Some participants got the vaccine, while others got dummy shots. Pfizer released no specific breakdowns, but for the vaccine to be 90% effective, nearly all the infections must have occurred in placebo recipients. The study is continuing, and Pfizer cautioned that the protection rate might change as more COVID-19 cases are added to the calculations.

Dr. Jesse Goodman of Georgetown University, former chief of the FDA's vaccine division, called the partial results "extremely promising" but ticked off many questions still to be answered, including how long the vaccine's effects last and whether it protects older people as well as younger ones.

Trump, who had suggested repeatedly during the presidential campaign that a vaccine could be ready by Election Day, tweeted: "STOCK MARKET UP BIG, VACCINE COMING SOON. REPORT 90% EFFECTIVE. SUCH GREAT NEWS!"

Biden, for his part, welcomed the news but cautioned that it could be many months before vaccinations become widespread in the U.S., and he warned Americans to rely on masks and social distancing in the meantime. He said the country still faces a "dark winter."

Confirmed infections in the U.S. eclipsed 10 million at the start of this week, the highest in the world. New cases are running at all-time highs of more than 100,000 per day. And tens of thousands more deaths are feared in the coming months, with the onset of cold weather and the holidays.

Pfizer's vaccine is among four candidates already in huge studies in the U.S., with still more being tested in other countries. Another U.S. company, Moderna Inc., also hopes to file an application with the FDA late this month.

Both companies' shots are made with a brand-new technology. These "mRNA vaccines" aren't made with the coronavirus itself, meaning there's no chance anyone could catch it from the shots. Instead, the vaccine contains a piece of genetic code that trains the immune system to recognize the spiked protein on the surface of the virus.

Despite cheering the news at one point, Trump posted a series of tweets later Monday accusing Pfizer and the U.S. Food and Drug Administration of waiting until after the election to announce its positive vaccine news for political reasons. But it's important to realize this success had very little to do with Operation Warp Speed.

Pfizer has insisted that its work is not influenced by politics and that it was "moving at the speed of science." The company itself learned of the interim results on Sunday after its independent data monitors met to discuss them. The FDA was not involved in Pfizer's decision to announce its early results and did not make any announcements of its own.

Out of Trump's shadow

Pfizer initially opted not to join the Trump administration's Operation Warp Speed, which helped fund a half-dozen vaccine makers' research and manufacturing scale-up. Pfizer instead said it has invested $2 billion of its own money in testing and expanding manufacturing capacity. But in July, Pfizer signed a contract to supply the U.S. with 100 million doses for $1.95 billion, assuming the vaccine is cleared by the FDA.

Pfizer said its only involvement in Operation Warp Speed is that those doses are part of the administration's goal to have 300 million doses of COVID-19 vaccines ready sometime next year.

Its partner, BioNTech SE, has received money -- from the German government, reportedly to the tune of $450 million. BioNTech is credited for contributing the messenger RNA technology, which prompts the body to make a key protein from the virus, creating an immune response. The biotechnology company already had a history of working with Pfizer on influenza vaccines, and in March they clinched a deal to co-develop a shot to prevent against COVID-19 at research sites both in the U.S. and Germany. The two companies began human testing of the vaccine in April, before the existence of Operation Warp Speed was even revealed publicly.

The son of a Turkish immigrant working at a Ford factory in the German city of Cologne, BioNTech Chief Executive Uğur Şahin, 55, now figures among the 100 richest Germans, together with his wife and fellow board member Özlem Türeci, 53, according to weekly Welt am Sonntag.

The market value of Nasdaq-listed BioNTech, which the pair co-founded, had ballooned to $21 billion as of Friday's close from $4.6 billion a year ago, with the firm set to play a major role in mass immunization against the coronavirus.

Şahin in January came across a scientific paper on a new coronavirus outbreak in the Chinese city of Wuhan and it struck him how small the step was from anti-cancer mRNA drugs to mRNA-based viral vaccines.

BioNTech quickly assigned about 500 staff to project "light speed" to work on several possible compounds, winning pharma giant Pfizer and Chinese drugmaker Fosun as partners in March.

The results have been even better than expected. Scientists have warned for months that any COVID-19 shot may be only as good as flu vaccines, which are about 50% effective and require yearly immunizations. Earlier this year, Fauci said he would be happy with a COVID-19 vaccine that was 60% effective.

Whatever the ultimate level of protection, no one knows if people will need regular vaccinations.

Also, volunteers in the study received a coronavirus test only if they developed symptoms, leaving unanswered whether vaccinated people could get infected but show no symptoms and unknowingly spread the virus.

Pfizer has estimated it could have 50 million doses available globally by the end of 2020, enough for 25 million people. Although the news was heralded as a great triumph for the entire human race, this particular vaccine alone is unlikely to lead us all out of the woods. That's because the Trump administration isn't the only one to have placed a pre-order. Combined with its storage and handling requirements, is unlikely to bring relief to anyone outside a handful of rich countries anytime soon.

The Pfizer CEO has estimated their capacity to deliver 1.3 billion doses through 2021, including the 50 million doses this year if they manage to gain regulatory approval or at least an EUA by December. Their pre-orders are from:

The EU- 200 million, with an option for a further 100 million doses.

Japan -120 million

USA- 100 million with an option for 500 million more

UK- 40 million doses

Canada - 20 million

So if the US and EU were to exercise their options, much of the Pfizer CEO's stated capacity (that itself is likely overstated) would be exhausted. That is probably why a group of UN experts released a statement criticising countries that are "trying to monopolise any future vaccine against COVID-19." But apart from them, mostly the news was received in good spirits all around. Except by Zoom, whose shares promptly tumbled by 20%.

Additional reporting by Daily Sabah.