By Michael Erman and Julie Steenhuysen

(Reuters) – Pfizer Inc’s experimental COVID-19 vaccine is more than 90% effective based on initial trial results, the drugmaker said on Monday, a major victory in the war against a virus that has killed over a million people and battered the world’s economy.

Experts welcomed the first successful interim data from a large-scale clinical test as a watershed moment that showed vaccines could help halt the pandemic, although mass roll-outs, which needs regulatory approval, will not happen this year.

Pfizer and German partner BioNTech SE said they had found no serious safety concerns yet and expected to seek U.S. authorization this month for emergency use of the vaccine, raising the chance of a regulatory decision as soon as December.

If granted, the companies estimate they can roll out up to 50 million doses this year, enough to protect 25 million people, and then produce up to 1.3 billion doses in 2021.

“Today is a great day for science and humanity,” said Pfizer Chief Executive Albert Bourla.

“We are reaching this critical milestone in our vaccine development program at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen,” he said.

Experts said they still wanted to see the full trial data, which have yet to be peer-reviewed or published in a medical journal, but the preliminary results looked encouraging.

“This news made me smile from ear to ear. It is a relief to see such positive results on this vaccine and bodes well for COVID-19 vaccines in general,” said Peter Horby, professor of emerging infectious diseases at the University of Oxford.

There are still many questions, such as how effective the vaccine is by ethnicity or age, and how long it will provide immunity, with the “new normal” of social distancing and face covering set to remain for the foreseeable future.

Pfizer expects to seek U.S. emergency use authorization for people aged 16 to 85. To do so, it will need two months of safety data from about half the study’s 44,000 participants, which is expected in the third week of November.

U.S. Health and Human Services Secretary Alex Azar said it would take several weeks for U.S. regulators to receive and process data on the vaccine before the government could potentially approve it.

MARKETS SURGE

The prospect of a vaccine electrified world markets with the S&P 500 and Dow hitting record highs as shares of banks, oil companies and travel companies soared. Shares in companies that have thrived during lockdowns, such as conferencing platform Zoom Video and online retailers, tumbled.

Pfizer shares jumped more than 11% to their highest since July last year, while BioNTech’s stock hit a record high.

Shares of other vaccine developers in the final stage of testing also rose with Johnson & Johnson up 4% and Moderna Inc, whose vaccine uses a similar technology as the Pfizer shot, up 8%. Britain’s AstraZeneca, however, fell 2%. Moderna is expected to report results from its large-scale trial later this month.

“The efficacy data are really impressive. This is better than most of us anticipated,” said William Schaffner, infectious diseases expert at Vanderbilt University School of Medicine in Nashville, Tennessee. “The study isn’t completed yet, but nonetheless the data look very solid.”

U.S. President Donald Trump welcomed the test results, and the market boost: “STOCK MARKET UP BIG, VACCINE COMING SOON. REPORT 90% EFFECTIVE. SUCH GREAT NEWS!” he tweeted.

President-elect Joe Biden said the news was excellent but did not change the fact that face masks, social distancing and other health measures would be needed well into next year.

The World Health Organization said the results were very positive, but warned there was a funding gap of $4.5 billion that could slow access to tests, medicines and vaccines in low- and middle-income countries.

‘NEAR ECSTATIC’

“I’m near ecstatic,” Bill Gruber, one of Pfizer’s top vaccine scientists, said in an interview. “This is a great day for public health and for the potential to get us all out of the circumstances we’re now in.”

Between 55% and 65% of the population will need to be vaccinated to break the dynamic of the spread of COVID-19, said Germany’s health minister Jens Spahn, adding that he did not expect a shot to be available before the first quarter of 2021.

The European Union said on Monday it would soon sign a contract for up to 300 million doses of the Pfizer and BioNTech COVID-19 vaccine.

The companies have a $1.95 billion contract with the U.S. government to deliver 100 million vaccine doses beginning this year. They did not receive research funding from the Trump administration’s Operation Warp Speed vaccine program.

The drugmakers have also reached supply agreements with the United Kingdom, Canada and Japan.

Pfizer said the interim analysis, conducted after 94 participants in the trial developed COVID-19, examined how many had received the vaccine versus a placebo.

Pfizer did not break down how many of those who fell ill received the vaccine. Still, over 90% effectiveness implies that no more than 8 of the 94 had been given the vaccine, which was administered in two shots about three weeks apart.

The efficacy rate, which could drop once full results are available, is well above the 50% effectiveness required by the U.S. Food and Drug Administration for a coronavirus vaccine.

Shortly after Pfizer’s announcement, Russia said its Sputnik V vaccine was also more than 90% effective, based on data collated from inoculations of the public. Its preliminary Phase III trial data is due to be published this month.

MORE DATA NEEDED

To confirm the efficacy rate, Pfizer said it would continue its trial until there were 164 COVID-19 cases among volunteers. Bourla told CNBC on Monday that based on rising infection rates, the trial could be completed before the end of November.

Pfizer said its data would be peer reviewed once it has results from the entire trial.

“These are interesting first signals, but again they are only communicated in press releases,” said Marylyn Addo, head of tropical medicine at the University Medical Center Hamburg-Eppendorf in Germany.

Dozens of drugmakers and research groups around the globe have been racing to develop vaccines against COVID-19, which on Sunday exceeded 50 million cases since the new coronavirus first emerged late last year in China.

The Pfizer and BioNTech vaccine uses messenger RNA (mRNA) technology, which relies on synthetic genes that can be generated and manufactured in weeks, and produced at scale more rapidly than conventional vaccines. The technology is designed to trigger an immune response without using pathogens, such as actual virus particles.

The Trump administration has said it will have enough vaccine doses for all of the 330 million U.S. residents who want it by the middle of 2021.

(Reporting by Michael Erman and Julie Steenhuysen; Additional reporting by Michele Gershberg in New York, Ludwig Burger and Patricia Weiss in Frankfurt and Kate Kelland in London; Editing by Bill Berkrot, Caroline Humer, Edwina Gibbs and David Clarke)