Finally, there seems to be some light at the end of what looks like a long, long tunnel. After being pummelled by the ravages of the much hated and feared coronavirus for months, which has killed over a million people, the news that Pfizer Inc’s experimental COVID-19 vaccine is more than 90 per cent effective based on initial trial results renewed hope on Monday among world leaders, scientists and global investors.

Scientists, public health officials and investors welcomed the development as a watershed moment that could help turn the tide of the pandemic if the full trial results pan out.

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

Chile’s President Sebastian Pinera said his country was in a “privileged and opportune” position to be able to roll out a COVID-19 vaccination campaign early next year.

Canadian Prime Minister Justin Trudeau hoped “a vaccine is coming early next year.”

Pfizer and German partner BioNTech SE said they had found no serious safety concerns yet and expected to seek US authorisation 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.

The feat even buoyed the stock markets. However, there are some challenges to be faced.

Will enough people take the vaccine? With COVID-19 vaccine trial results looking positive, governments and pharmaceutical firms face their next daunting challenge: convincing the world to get inoculated. The World Health Organisation estimates that about 70 per cent of people must be inoculated to break transmission of the virus.

The vaccine, which is based on a novel technology that uses synthetic mRNA to activate the immune system against the virus, needs to be kept at supercooled temperatures of minus 70 degrees Celsius (-94 F) or below.

There are other questions, such as how effective the vaccine is by ethnicity or age, and how long it will provide immunity. More has to be investigated on production capabilities and rollout.

Mass roll-outs, which need regulatory approval, will not happen this year and several vaccines are seen as necessary to meet massive global needs. Pfizer and BioNTech need to get regulators to sign off on the shot before vaccines can be shipped to those considered most in need by governments.

Spain is going to get the first vaccines against COVID-19 in early 2021, Health Minister Salvador Illa said on Tuesday. The country would initially get 20 million vaccine doses, enough to immunise 10 million people.

While cheering the development, Joe Biden, the new President-elect, said a coronavirus vaccine approval process must be guided by science so the public can have confidence it is safe and effective, warning that the United States is still facing a very dark winter and that a vaccine likely won’t be available for months.

British Prime Minister Boris Johnson said: “I must stress that these are very, very early days, and we’ve talked for a long time, right about the distant bugle of the scientific cavalry coming over the brow of the hill.”

Whatever may be the misgivings, it is a gamechanger for many sectors. With the coronavirus having infected more than 50 million people, the news has apparently come as a relief to many, who feel their prayers have finally been answered. As Peter Horby, professor of emerging infectious diseases at the University of Oxford, says, “This news made me smile from ear to ear.”