LONDON (AP) — Britain authorized an easy-to-handle coronavirus vaccine Wednesday and decided to stretch out the time between doses to allow more people to get some level of protection faster as infections surge. The first greenlight for the shot dubbed the "vaccine for the world" brought a measure of hope that the pandemic could be brought under control.

The vaccine developed by Oxford University and drugmaker AstraZeneca is expected to be relied on in many countries because of its low cost and the fact that it can be kept in refrigerators rather than at the ultra-cold or freezer temperatures some other vaccines require.

"This wonderful news brings renewed hope at a time of rising infections and unprecedented pressure on health services in the U.K. and beyond. It is now critical that this hope can be shared by all nations," said Anna Marriot, Health Policy Manager at Oxfam aid agency.

Even as the authorization was welcomed as a significant development in efforts to contain the virus that has killed nearly 1.8 million, the change in British policy on administering the shots drove home concerns about a new, potentially more contagious variant that authorities blame for rising hospitalizations in the United Kingdom. The new variant has been found in several countries, including the U.S.

Because infections are spreading so rapidly in the U.K., officials are now recommending prioritizing delivering a first dose to as many people as possible for both of the vaccines authorized for use in the country: the AstraZeneca one and another from Pfizer-BioNTech. Authorities say both protect people even after just one of the two recommended doses — and that increasing the time between doses might even have a benefit.

While the U.K.'s chief medical officers say the second dose may be important for longer term protection, one official said that the country urgently needed "rapid and high levels of vaccine uptake."

"This will allow the greatest number of eligible people to receive vaccine in the shortest time possible, and that will protect the greatest number of lives," Wei Shen Lim, chair of the U.K.'s Joint Committee on Vaccination and Immunisation, told reporters Wednesday.

Hundreds of thousands of people in the U.K. have already received at least one shot of the Pfizer-BioNTech vaccine. British Health Secretary Matt Hancock said the rollout of the AstraZeneca one will start Jan. 4. The government says everyone will get a second shot within 12 weeks of the first.

AstraZeneca noted that a pause of between four and 12 weeks between doses has been shown to be effective in trials.

"The immune response data show that as you have a longer gap between the two doses, you do see higher immune responses," Oxford University's Dr. Andrew Pollard, one of the leaders of the vaccine development team, told The Associated Press. "That's not a surprise, that's what we see with many vaccines."

But Pfizer responded to the new policy by saying that any "alternative" dosing regimens should be tracked by health authorities. It noted that two doses are needed for "maximum protection" against the disease, and that it has no data that shows protection from just one dose lasts longer than 21 days. The vaccine was tested with two doses, three weeks apart.

The Medicines and Healthcare Products Regulatory Agency, which recommended the AstraZeneca vaccine for emergency use, did not endorse one vaccine over the other. And it updated its guidance on the Pfizer vaccine, saying it could be given to pregnant and breastfeeding women. It added that only people with an allergy to its ingredients should avoid it, rather than people with severe allergies to food, vaccines and medicines in general.

Independent experts, meanwhile, welcomed the decision to spread out shots, saying that giving more people the first dose quickly could be crucial, coming as the number of hospitalized COVID-19 patients in the U.K. has surpassed the first peak of the outbreak in the spring, with authorities blaming a new variant that was first identified in southeast England.

"With the rapidly spreading new variant, I have no doubt this decision will save many lives," said Paul Hunter, professor of medicine at the University of East Anglia's Norwich School of Medicine.

Britain has recorded more than 71,000 confirmed coronavirus deaths, the second-highest death toll in Europe after Italy, and reported a record number of new confirmed cases Tuesday. In an effort to slow the spread, the British government on Wednesday extended its toughest coronavirus restrictions to more than three-quarters of England's population.

Experts believe the vaccines already authorized will work against the new variant, but they are continuing to study that.

Beyond Britain, there are hopes the AstraZeneca shot, which Pollard has called a "vaccine for the world," will offer a path out of the pandemic.

The ultra-cold or freezer temperature storage required by other vaccines is "very impractical" in developing countries, said Dr. Gillies O'Bryan-Tear, chair of policy and communications for Britain's Faculty of Pharmaceutical Medicine. It means the AstraZeneca one "may reach more parts of the world than the Pfizer one," he said.

The company has also said it will sell it for $2.50 a dose and plans to make up to 3 billion doses by the end of 2021.

Partial results from studies in almost 24,000 people in Britain, Brazil and South Africa suggest the AstraZeneca shots are safe and about 70% effective for preventing illness from coronavirus infection.

Questions also remain about how well the vaccine protects older people. Only 12% of study participants were over 55 and they were enrolled later, so there hasn't been enough time to see whether they develop infections at a lower rate than those not given the vaccine.

Britain's action likely means the World Health Organization could soon clear the AstraZeneca vaccine for use in a global effort to help poor countries, called COVAX. The initiative has secured access to at least 100 million doses of the vaccine, with options and other deals to buy more. But none can be distributed until greenlighted by WHO.

The U.N. health agency does not license or regulate vaccines itself, but typically evaluates vaccines once they have been approved by a regulator such as the U.K.'s. WHO experts can then recommend that the shots to be "pre-qualified" so they can be bought by donors for developing countries.

Most coronavirus vaccines to be used in poorer countries likely will be made by the Serum Institute of India, which has been contracted by AstraZeneca to make 1 billion doses. In June, the pharmaceutical company announced that the Serum Institute would produce 400 million doses by the end of 2020 but as of early December, only about 50 million doses had been manufactured after production was halted several times.

In addition to the Serum Institute, AstraZeneca has deals with vaccine makers in Brazil, South Africa and China.

Munir Pirmohamed, of the Commission on Human Medicines, added a note of caution following Wednesday's authorization of the vaccine.

"Everybody said that we can now see the light at the end of the tunnel. I completely agree with that," he said. "However, we we're not there yet. While we hurtle towards that light, it is really important that everybody continues to follow government guidelines."

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Corder reported from The Hague, Netherlands. Associated Press writers Maria Cheng in Toronto, Jill Lawless in London and John Leicester in Le Pecq, France, contributed.